Merge pull request #48221 from nekomatata/solver-multithreaded

Godot Physics collisions and solver processed on threads

servers/physics_2d/area_pair_2d_sw.cpp

@@ -40,31 +40,48 @@ bool AreaPair2DSW::setup(real_t p_step) {
 		result = true;
 	}
 
+	process_collision = false;
 	if (result != colliding) {
-		if (result) {
-			if (area->get_space_override_mode() != PhysicsServer2D::AREA_SPACE_OVERRIDE_DISABLED) {
-				body->add_area(area);
-			}
-			if (area->has_monitor_callback()) {
-				area->add_body_to_query(body, body_shape, area_shape);
-			}
-
-		} else {
-			if (area->get_space_override_mode() != PhysicsServer2D::AREA_SPACE_OVERRIDE_DISABLED) {
-				body->remove_area(area);
-			}
-			if (area->has_monitor_callback()) {
-				area->remove_body_from_query(body, body_shape, area_shape);
-			}
+		if (area->get_space_override_mode() != PhysicsServer2D::AREA_SPACE_OVERRIDE_DISABLED) {
+			process_collision = true;
+		} else if (area->has_monitor_callback()) {
+			process_collision = true;
 		}
 
 		colliding = result;
 	}
 
-	return false; //never do any post solving
+	return process_collision;
+}
+
+bool AreaPair2DSW::pre_solve(real_t p_step) {
+	if (!process_collision) {
+		return false;
+	}
+
+	if (colliding) {
+		if (area->get_space_override_mode() != PhysicsServer2D::AREA_SPACE_OVERRIDE_DISABLED) {
+			body->add_area(area);
+		}
+
+		if (area->has_monitor_callback()) {
+			area->add_body_to_query(body, body_shape, area_shape);
+		}
+	} else {
+		if (area->get_space_override_mode() != PhysicsServer2D::AREA_SPACE_OVERRIDE_DISABLED) {
+			body->remove_area(area);
+		}
+
+		if (area->has_monitor_callback()) {
+			area->remove_body_from_query(body, body_shape, area_shape);
+		}
+	}
+
+	return false; // Never do any post solving.
 }
 
 void AreaPair2DSW::solve(real_t p_step) {
+	// Nothing to do.
 }
 
 AreaPair2DSW::AreaPair2DSW(Body2DSW *p_body, int p_body_shape, Area2DSW *p_area, int p_area_shape) {
@@ -72,7 +89,6 @@ AreaPair2DSW::AreaPair2DSW(Body2DSW *p_body, int p_body_shape, Area2DSW *p_area,
 	area = p_area;
 	body_shape = p_body_shape;
 	area_shape = p_area_shape;
-	colliding = false;
 	body->add_constraint(this, 0);
 	area->add_constraint(this);
 	if (p_body->get_mode() == PhysicsServer2D::BODY_MODE_KINEMATIC) { //need to be active to process pair
@@ -103,33 +119,48 @@ bool Area2Pair2DSW::setup(real_t p_step) {
 		result = true;
 	}
 
+	process_collision = false;
 	if (result != colliding) {
-		if (result) {
-			if (area_b->has_area_monitor_callback() && area_a->is_monitorable()) {
-				area_b->add_area_to_query(area_a, shape_a, shape_b);
-			}
-
-			if (area_a->has_area_monitor_callback() && area_b->is_monitorable()) {
-				area_a->add_area_to_query(area_b, shape_b, shape_a);
-			}
-
-		} else {
-			if (area_b->has_area_monitor_callback() && area_a->is_monitorable()) {
-				area_b->remove_area_from_query(area_a, shape_a, shape_b);
-			}
-
-			if (area_a->has_area_monitor_callback() && area_b->is_monitorable()) {
-				area_a->remove_area_from_query(area_b, shape_b, shape_a);
-			}
+		if (area_b->has_area_monitor_callback() && area_a->is_monitorable()) {
+			process_collision = true;
+		} else if (area_a->has_area_monitor_callback() && area_b->is_monitorable()) {
+			process_collision = true;
 		}
 
 		colliding = result;
 	}
 
-	return false; //never do any post solving
+	return process_collision;
+}
+
+bool Area2Pair2DSW::pre_solve(real_t p_step) {
+	if (!process_collision) {
+		return false;
+	}
+
+	if (colliding) {
+		if (area_b->has_area_monitor_callback() && area_a->is_monitorable()) {
+			area_b->add_area_to_query(area_a, shape_a, shape_b);
+		}
+
+		if (area_a->has_area_monitor_callback() && area_b->is_monitorable()) {
+			area_a->add_area_to_query(area_b, shape_b, shape_a);
+		}
+	} else {
+		if (area_b->has_area_monitor_callback() && area_a->is_monitorable()) {
+			area_b->remove_area_from_query(area_a, shape_a, shape_b);
+		}
+
+		if (area_a->has_area_monitor_callback() && area_b->is_monitorable()) {
+			area_a->remove_area_from_query(area_b, shape_b, shape_a);
+		}
+	}
+
+	return false; // Never do any post solving.
 }
 
 void Area2Pair2DSW::solve(real_t p_step) {
+	// Nothing to do.
 }
 
 Area2Pair2DSW::Area2Pair2DSW(Area2DSW *p_area_a, int p_shape_a, Area2DSW *p_area_b, int p_shape_b) {
@@ -137,7 +168,6 @@ Area2Pair2DSW::Area2Pair2DSW(Area2DSW *p_area_a, int p_shape_a, Area2DSW *p_area
 	area_b = p_area_b;
 	shape_a = p_shape_a;
 	shape_b = p_shape_b;
-	colliding = false;
 	area_a->add_constraint(this);
 	area_b->add_constraint(this);
 }

servers/physics_2d/area_pair_2d_sw.h

@@ -36,30 +36,34 @@
 #include "constraint_2d_sw.h"
 
 class AreaPair2DSW : public Constraint2DSW {
-	Body2DSW *body;
-	Area2DSW *area;
-	int body_shape;
-	int area_shape;
-	bool colliding;
+	Body2DSW *body = nullptr;
+	Area2DSW *area = nullptr;
+	int body_shape = 0;
+	int area_shape = 0;
+	bool colliding = false;
+	bool process_collision = false;
 
 public:
-	bool setup(real_t p_step);
-	void solve(real_t p_step);
+	virtual bool setup(real_t p_step) override;
+	virtual bool pre_solve(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
 
 	AreaPair2DSW(Body2DSW *p_body, int p_body_shape, Area2DSW *p_area, int p_area_shape);
 	~AreaPair2DSW();
 };
 
 class Area2Pair2DSW : public Constraint2DSW {
-	Area2DSW *area_a;
-	Area2DSW *area_b;
-	int shape_a;
-	int shape_b;
-	bool colliding;
+	Area2DSW *area_a = nullptr;
+	Area2DSW *area_b = nullptr;
+	int shape_a = 0;
+	int shape_b = 0;
+	bool colliding = false;
+	bool process_collision = false;
 
 public:
-	bool setup(real_t p_step);
-	void solve(real_t p_step);
+	virtual bool setup(real_t p_step) override;
+	virtual bool pre_solve(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
 
 	Area2Pair2DSW(Area2DSW *p_area_a, int p_shape_a, Area2DSW *p_area_b, int p_shape_b);
 	~Area2Pair2DSW();

servers/physics_2d/body_2d_sw.cpp

@@ -104,31 +104,17 @@ void Body2DSW::set_active(bool p_active) {
 	}
 
 	active = p_active;
-	if (!p_active) {
-		if (get_space()) {
-			get_space()->body_remove_from_active_list(&active_list);
-		}
-	} else {
+
+	if (active) {
 		if (mode == PhysicsServer2D::BODY_MODE_STATIC) {
-			return; //static bodies can't become active
-		}
-		if (get_space()) {
+			// Static bodies can't be active.
+			active = false;
+		} else if (get_space()) {
 			get_space()->body_add_to_active_list(&active_list);
 		}
-
-		//still_time=0;
-	}
-	/*
-	if (!space)
-		return;
-
-	for(int i=0;i<get_shape_count();i++) {
-		Shape &s=shapes[i];
-		if (s.bpid>0) {
-			get_space()->get_broadphase()->set_active(s.bpid,active);
-		}
+	} else if (get_space()) {
+		get_space()->body_remove_from_active_list(&active_list);
 	}
-*/
 }
 
 void Body2DSW::set_param(PhysicsServer2D::BodyParameter p_param, real_t p_value) {
@@ -370,13 +356,6 @@ void Body2DSW::set_space(Space2DSW *p_space) {
 		if (active) {
 			get_space()->body_add_to_active_list(&active_list);
 		}
-		/*
-		_update_queries();
-		if (is_active()) {
-			active=false;
-			set_active(true);
-		}
-		*/
 	}
 
 	first_integration = false;

servers/physics_2d/body_pair_2d_sw.cpp

@@ -87,10 +87,13 @@ void BodyPair2DSW::_contact_added_callback(const Vector2 &p_point_A, const Vecto
 		int least_deep = -1;
 		real_t min_depth = 1e10;
 
+		const Transform2D &transform_A = A->get_transform();
+		const Transform2D &transform_B = B->get_transform();
+
 		for (int i = 0; i <= contact_count; i++) {
 			Contact &c = (i == contact_count) ? contact : contacts[i];
-			Vector2 global_A = A->get_transform().basis_xform(c.local_A);
-			Vector2 global_B = B->get_transform().basis_xform(c.local_B) + offset_B;
+			Vector2 global_A = transform_A.basis_xform(c.local_A);
+			Vector2 global_B = transform_B.basis_xform(c.local_B) + offset_B;
 
 			Vector2 axis = global_A - global_B;
 			real_t depth = axis.dot(c.normal);
@@ -124,6 +127,9 @@ void BodyPair2DSW::_validate_contacts() {
 	real_t max_separation = space->get_contact_max_separation();
 	real_t max_separation2 = max_separation * max_separation;
 
+	const Transform2D &transform_A = A->get_transform();
+	const Transform2D &transform_B = B->get_transform();
+
 	for (int i = 0; i < contact_count; i++) {
 		Contact &c = contacts[i];
 
@@ -134,8 +140,8 @@ void BodyPair2DSW::_validate_contacts() {
 		} else {
 			c.reused = false;
 
-			Vector2 global_A = A->get_transform().basis_xform(c.local_A);
-			Vector2 global_B = B->get_transform().basis_xform(c.local_B) + offset_B;
+			Vector2 global_A = transform_A.basis_xform(c.local_A);
+			Vector2 global_B = transform_B.basis_xform(c.local_B) + offset_B;
 			Vector2 axis = global_A - global_B;
 			real_t depth = axis.dot(c.normal);
 
@@ -220,14 +226,16 @@ real_t combine_friction(Body2DSW *A, Body2DSW *B) {
 }
 
 bool BodyPair2DSW::setup(real_t p_step) {
-	//cannot collide
+	dynamic_A = (A->get_mode() > PhysicsServer2D::BODY_MODE_KINEMATIC);
+	dynamic_B = (B->get_mode() > PhysicsServer2D::BODY_MODE_KINEMATIC);
+
 	if (!A->test_collision_mask(B) || A->has_exception(B->get_self()) || B->has_exception(A->get_self())) {
 		collided = false;
 		return false;
 	}
 
-	bool report_contacts_only = false;
-	if ((A->get_mode() <= PhysicsServer2D::BODY_MODE_KINEMATIC) && (B->get_mode() <= PhysicsServer2D::BODY_MODE_KINEMATIC)) {
+	report_contacts_only = false;
+	if (!dynamic_A && !dynamic_B) {
 		if ((A->get_max_contacts_reported() > 0) || (B->get_max_contacts_reported() > 0)) {
 			report_contacts_only = true;
 		} else {
@@ -246,12 +254,12 @@ bool BodyPair2DSW::setup(real_t p_step) {
 
 	_validate_contacts();
 
-	Vector2 offset_A = A->get_transform().get_origin();
+	const Vector2 &offset_A = A->get_transform().get_origin();
 	Transform2D xform_Au = A->get_transform().untranslated();
 	Transform2D xform_A = xform_Au * A->get_shape_transform(shape_A);
 
 	Transform2D xform_Bu = B->get_transform();
-	xform_Bu.elements[2] -= A->get_transform().get_origin();
+	xform_Bu.elements[2] -= offset_A;
 	Transform2D xform_B = xform_Bu * B->get_shape_transform(shape_B);
 
 	Shape2DSW *shape_A_ptr = A->get_shape(shape_A);
@@ -272,13 +280,13 @@ bool BodyPair2DSW::setup(real_t p_step) {
 	if (!collided) {
 		//test ccd (currently just a raycast)
 
-		if (A->get_continuous_collision_detection_mode() == PhysicsServer2D::CCD_MODE_CAST_RAY && A->get_mode() > PhysicsServer2D::BODY_MODE_KINEMATIC) {
+		if (A->get_continuous_collision_detection_mode() == PhysicsServer2D::CCD_MODE_CAST_RAY && dynamic_A) {
 			if (_test_ccd(p_step, A, shape_A, xform_A, B, shape_B, xform_B)) {
 				collided = true;
 			}
 		}
 
-		if (B->get_continuous_collision_detection_mode() == PhysicsServer2D::CCD_MODE_CAST_RAY && B->get_mode() > PhysicsServer2D::BODY_MODE_KINEMATIC) {
+		if (B->get_continuous_collision_detection_mode() == PhysicsServer2D::CCD_MODE_CAST_RAY && dynamic_B) {
 			if (_test_ccd(p_step, B, shape_B, xform_B, A, shape_A, xform_A, true)) {
 				collided = true;
 			}
@@ -338,9 +346,21 @@ bool BodyPair2DSW::setup(real_t p_step) {
 		}
 	}
 
+	return true;
+}
+
+bool BodyPair2DSW::pre_solve(real_t p_step) {
+	if (!collided || oneway_disabled) {
+		return false;
+	}
+
 	real_t max_penetration = space->get_contact_max_allowed_penetration();
 
 	real_t bias = 0.3;
+
+	Shape2DSW *shape_A_ptr = A->get_shape(shape_A);
+	Shape2DSW *shape_B_ptr = B->get_shape(shape_B);
+
 	if (shape_A_ptr->get_custom_bias() || shape_B_ptr->get_custom_bias()) {
 		if (shape_A_ptr->get_custom_bias() == 0) {
 			bias = shape_B_ptr->get_custom_bias();
@@ -351,21 +371,23 @@ bool BodyPair2DSW::setup(real_t p_step) {
 		}
 	}
 
-	cc = 0;
-
 	real_t inv_dt = 1.0 / p_step;
 
 	bool do_process = false;
 
+	const Vector2 &offset_A = A->get_transform().get_origin();
+	const Transform2D &transform_A = A->get_transform();
+	const Transform2D &transform_B = B->get_transform();
+
 	for (int i = 0; i < contact_count; i++) {
 		Contact &c = contacts[i];
-
 		c.active = false;
 
-		Vector2 global_A = xform_Au.xform(c.local_A);
-		Vector2 global_B = xform_Bu.xform(c.local_B);
+		Vector2 global_A = transform_A.basis_xform(c.local_A);
+		Vector2 global_B = transform_B.basis_xform(c.local_B) + offset_B;
 
-		real_t depth = c.normal.dot(global_A - global_B);
+		Vector2 axis = global_A - global_B;
+		real_t depth = axis.dot(c.normal);
 
 		if (depth <= 0 || !c.reused) {
 			continue;
@@ -396,8 +418,6 @@ bool BodyPair2DSW::setup(real_t p_step) {
 			continue;
 		}
 
-		c.active = true;
-
 		// Precompute normal mass, tangent mass, and bias.
 		real_t rnA = c.rA.dot(c.normal);
 		real_t rnB = c.rB.dot(c.normal);
@@ -421,8 +441,12 @@ bool BodyPair2DSW::setup(real_t p_step) {
 			// Apply normal + friction impulse
 			Vector2 P = c.acc_normal_impulse * c.normal + c.acc_tangent_impulse * tangent;
 
-			A->apply_impulse(-P, c.rA);
-			B->apply_impulse(P, c.rB);
+			if (dynamic_A) {
+				A->apply_impulse(-P, c.rA);
+			}
+			if (dynamic_B) {
+				B->apply_impulse(P, c.rB);
+			}
 		}
 #endif
 
@@ -434,6 +458,7 @@ bool BodyPair2DSW::setup(real_t p_step) {
 			c.bounce = c.bounce * dv.dot(c.normal);
 		}
 
+		c.active = true;
 		do_process = true;
 	}
 
@@ -441,13 +466,12 @@ bool BodyPair2DSW::setup(real_t p_step) {
 }
 
 void BodyPair2DSW::solve(real_t p_step) {
-	if (!collided) {
+	if (!collided || oneway_disabled) {
 		return;
 	}
 
 	for (int i = 0; i < contact_count; ++i) {
 		Contact &c = contacts[i];
-		cc++;
 
 		if (!c.active) {
 			continue;
@@ -474,8 +498,12 @@ void BodyPair2DSW::solve(real_t p_step) {
 
 		Vector2 jb = c.normal * (c.acc_bias_impulse - jbnOld);
 
-		A->apply_bias_impulse(-jb, c.rA);
-		B->apply_bias_impulse(jb, c.rB);
+		if (dynamic_A) {
+			A->apply_bias_impulse(-jb, c.rA);
+		}
+		if (dynamic_B) {
+			B->apply_bias_impulse(jb, c.rB);
+		}
 
 		real_t jn = -(c.bounce + vn) * c.mass_normal;
 		real_t jnOld = c.acc_normal_impulse;
@@ -490,8 +518,12 @@ void BodyPair2DSW::solve(real_t p_step) {
 
 		Vector2 j = c.normal * (c.acc_normal_impulse - jnOld) + tangent * (c.acc_tangent_impulse - jtOld);
 
-		A->apply_impulse(-j, c.rA);
-		B->apply_impulse(j, c.rB);
+		if (dynamic_A) {
+			A->apply_impulse(-j, c.rA);
+		}
+		if (dynamic_B) {
+			B->apply_impulse(j, c.rB);
+		}
 	}
 }
 
@@ -504,9 +536,6 @@ BodyPair2DSW::BodyPair2DSW(Body2DSW *p_A, int p_shape_A, Body2DSW *p_B, int p_sh
 	space = A->get_space();
 	A->add_constraint(this, 0);
 	B->add_constraint(this, 1);
-	contact_count = 0;
-	collided = false;
-	oneway_disabled = false;
 }
 
 BodyPair2DSW::~BodyPair2DSW() {

servers/physics_2d/body_pair_2d_sw.h

@@ -44,13 +44,16 @@ class BodyPair2DSW : public Constraint2DSW {
 			Body2DSW *B;
 		};
 
-		Body2DSW *_arr[2];
+		Body2DSW *_arr[2] = { nullptr, nullptr };
 	};
 
-	int shape_A;
-	int shape_B;
+	int shape_A = 0;
+	int shape_B = 0;
 
-	Space2DSW *space;
+	bool dynamic_A = false;
+	bool dynamic_B = false;
+
+	Space2DSW *space = nullptr;
 
 	struct Contact {
 		Vector2 position;
@@ -73,10 +76,10 @@ class BodyPair2DSW : public Constraint2DSW {
 
 	Vector2 sep_axis;
 	Contact contacts[MAX_CONTACTS];
-	int contact_count;
-	bool collided;
-	bool oneway_disabled;
-	int cc;
+	int contact_count = 0;
+	bool collided = false;
+	bool oneway_disabled = false;
+	bool report_contacts_only = false;
 
 	bool _test_ccd(real_t p_step, Body2DSW *p_A, int p_shape_A, const Transform2D &p_xform_A, Body2DSW *p_B, int p_shape_B, const Transform2D &p_xform_B, bool p_swap_result = false);
 	void _validate_contacts();
@@ -84,8 +87,9 @@ class BodyPair2DSW : public Constraint2DSW {
 	_FORCE_INLINE_ void _contact_added_callback(const Vector2 &p_point_A, const Vector2 &p_point_B);
 
 public:
-	bool setup(real_t p_step);
-	void solve(real_t p_step);
+	virtual bool setup(real_t p_step) override;
+	virtual bool pre_solve(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
 
 	BodyPair2DSW(Body2DSW *p_A, int p_shape_A, Body2DSW *p_B, int p_shape_B);
 	~BodyPair2DSW();

servers/physics_2d/collision_object_2d_sw.h

@@ -143,8 +143,8 @@ public:
 		return shapes[p_index].metadata;
 	}
 
-	_FORCE_INLINE_ Transform2D get_transform() const { return transform; }
-	_FORCE_INLINE_ Transform2D get_inv_transform() const { return inv_transform; }
+	_FORCE_INLINE_ const Transform2D &get_transform() const { return transform; }
+	_FORCE_INLINE_ const Transform2D &get_inv_transform() const { return inv_transform; }
 	_FORCE_INLINE_ Space2DSW *get_space() const { return space; }
 
 	void set_shape_as_disabled(int p_idx, bool p_disabled);

servers/physics_2d/constraint_2d_sw.h

@@ -63,6 +63,7 @@ public:
 	_FORCE_INLINE_ bool is_disabled_collisions_between_bodies() const { return disabled_collisions_between_bodies; }
 
 	virtual bool setup(real_t p_step) = 0;
+	virtual bool pre_solve(real_t p_step) = 0;
 	virtual void solve(real_t p_step) = 0;
 
 	virtual ~Constraint2DSW() {}

servers/physics_2d/joints_2d_sw.cpp

@@ -97,7 +97,10 @@ normal_relative_velocity(Body2DSW *a, Body2DSW *b, Vector2 rA, Vector2 rB, Vecto
 }
 
 bool PinJoint2DSW::setup(real_t p_step) {
-	if ((A->get_mode() <= PhysicsServer2D::BODY_MODE_KINEMATIC) && (B->get_mode() <= PhysicsServer2D::BODY_MODE_KINEMATIC)) {
+	dynamic_A = (A->get_mode() > PhysicsServer2D::BODY_MODE_KINEMATIC);
+	dynamic_B = (B->get_mode() > PhysicsServer2D::BODY_MODE_KINEMATIC);
+
+	if (!dynamic_A && !dynamic_B) {
 		return false;
 	}
 
@@ -148,12 +151,6 @@ bool PinJoint2DSW::setup(real_t p_step) {
 
 	bias = delta * -(get_bias() == 0 ? space->get_constraint_bias() : get_bias()) * (1.0 / p_step);
 
-	// apply accumulated impulse
-	A->apply_impulse(-P, rA);
-	if (B) {
-		B->apply_impulse(P, rB);
-	}
-
 	return true;
 }
 
@@ -161,6 +158,18 @@ inline Vector2 custom_cross(const Vector2 &p_vec, real_t p_other) {
 	return Vector2(p_other * p_vec.y, -p_other * p_vec.x);
 }
 
+bool PinJoint2DSW::pre_solve(real_t p_step) {
+	// Apply accumulated impulse.
+	if (dynamic_A) {
+		A->apply_impulse(-P, rA);
+	}
+	if (B && dynamic_B) {
+		B->apply_impulse(P, rB);
+	}
+
+	return true;
+}
+
 void PinJoint2DSW::solve(real_t p_step) {
 	// compute relative velocity
 	Vector2 vA = A->get_linear_velocity() - custom_cross(rA, A->get_angular_velocity());
@@ -174,8 +183,10 @@ void PinJoint2DSW::solve(real_t p_step) {
 
 	Vector2 impulse = M.basis_xform(bias - rel_vel - Vector2(softness, softness) * P);
 
-	A->apply_impulse(-impulse, rA);
-	if (B) {
+	if (dynamic_A) {
+		A->apply_impulse(-impulse, rA);
+	}
+	if (B && dynamic_B) {
 		B->apply_impulse(impulse, rB);
 	}
 
@@ -262,14 +273,19 @@ mult_k(const Vector2 &vr, const Vector2 &k1, const Vector2 &k2) {
 }
 
 bool GrooveJoint2DSW::setup(real_t p_step) {
-	if ((A->get_mode() <= PhysicsServer2D::BODY_MODE_KINEMATIC) && (B->get_mode() <= PhysicsServer2D::BODY_MODE_KINEMATIC)) {
+	dynamic_A = (A->get_mode() > PhysicsServer2D::BODY_MODE_KINEMATIC);
+	dynamic_B = (B->get_mode() > PhysicsServer2D::BODY_MODE_KINEMATIC);
+
+	if (!dynamic_A && !dynamic_B) {
 		return false;
 	}
 
+	Space2DSW *space = A->get_space();
+	ERR_FAIL_COND_V(!space, false);
+
 	// calculate endpoints in worldspace
 	Vector2 ta = A->get_transform().xform(A_groove_1);
 	Vector2 tb = A->get_transform().xform(A_groove_2);
-	Space2DSW *space = A->get_space();
 
 	// calculate axis
 	Vector2 n = -(tb - ta).orthogonal().normalized();
@@ -308,14 +324,22 @@ bool GrooveJoint2DSW::setup(real_t p_step) {
 	real_t _b = get_bias();
 	gbias = (delta * -(_b == 0 ? space->get_constraint_bias() : _b) * (1.0 / p_step)).clamped(get_max_bias());
 
-	// apply accumulated impulse
-	A->apply_impulse(-jn_acc, rA);
-	B->apply_impulse(jn_acc, rB);
-
 	correct = true;
 	return true;
 }
 
+bool GrooveJoint2DSW::pre_solve(real_t p_step) {
+	// Apply accumulated impulse.
+	if (dynamic_A) {
+		A->apply_impulse(-jn_acc, rA);
+	}
+	if (dynamic_B) {
+		B->apply_impulse(jn_acc, rB);
+	}
+
+	return true;
+}
+
 void GrooveJoint2DSW::solve(real_t p_step) {
 	// compute impulse
 	Vector2 vr = relative_velocity(A, B, rA, rB);
@@ -328,8 +352,12 @@ void GrooveJoint2DSW::solve(real_t p_step) {
 
 	j = jn_acc - jOld;
 
-	A->apply_impulse(-j, rA);
-	B->apply_impulse(j, rB);
+	if (dynamic_A) {
+		A->apply_impulse(-j, rA);
+	}
+	if (dynamic_B) {
+		B->apply_impulse(j, rB);
+	}
 }
 
 GrooveJoint2DSW::GrooveJoint2DSW(const Vector2 &p_a_groove1, const Vector2 &p_a_groove2, const Vector2 &p_b_anchor, Body2DSW *p_body_a, Body2DSW *p_body_b) :
@@ -351,7 +379,10 @@ GrooveJoint2DSW::GrooveJoint2DSW(const Vector2 &p_a_groove1, const Vector2 &p_a_
 //////////////////////////////////////////////
 
 bool DampedSpringJoint2DSW::setup(real_t p_step) {
-	if ((A->get_mode() <= PhysicsServer2D::BODY_MODE_KINEMATIC) && (B->get_mode() <= PhysicsServer2D::BODY_MODE_KINEMATIC)) {
+	dynamic_A = (A->get_mode() > PhysicsServer2D::BODY_MODE_KINEMATIC);
+	dynamic_B = (B->get_mode() > PhysicsServer2D::BODY_MODE_KINEMATIC);
+
+	if (!dynamic_A && !dynamic_B) {
 		return false;
 	}
 
@@ -373,12 +404,21 @@ bool DampedSpringJoint2DSW::setup(real_t p_step) {
 	target_vrn = 0.0f;
 	v_coef = 1.0f - Math::exp(-damping * (p_step)*k);
 
-	// apply spring force
+	// Calculate spring force.
 	real_t f_spring = (rest_length - dist) * stiffness;
-	Vector2 j = n * f_spring * (p_step);
+	j = n * f_spring * (p_step);
 
-	A->apply_impulse(-j, rA);
-	B->apply_impulse(j, rB);
+	return true;
+}
+
+bool DampedSpringJoint2DSW::pre_solve(real_t p_step) {
+	// Apply spring force.
+	if (dynamic_A) {
+		A->apply_impulse(-j, rA);
+	}
+	if (dynamic_B) {
+		B->apply_impulse(j, rB);
+	}
 
 	return true;
 }
@@ -393,8 +433,12 @@ void DampedSpringJoint2DSW::solve(real_t p_step) {
 	target_vrn = vrn + v_damp;
 	Vector2 j = n * v_damp * n_mass;
 
-	A->apply_impulse(-j, rA);
-	B->apply_impulse(j, rB);
+	if (dynamic_A) {
+		A->apply_impulse(-j, rA);
+	}
+	if (dynamic_B) {
+		B->apply_impulse(j, rB);
+	}
 }
 
 void DampedSpringJoint2DSW::set_param(PhysicsServer2D::DampedSpringParam p_param, real_t p_value) {

servers/physics_2d/joints_2d_sw.h

@@ -39,6 +39,10 @@ class Joint2DSW : public Constraint2DSW {
 	real_t bias;
 	real_t max_bias;
 
+protected:
+	bool dynamic_A = false;
+	bool dynamic_B = false;
+
 public:
 	_FORCE_INLINE_ void set_max_force(real_t p_force) { max_force = p_force; }
 	_FORCE_INLINE_ real_t get_max_force() const { return max_force; }
@@ -49,8 +53,9 @@ public:
 	_FORCE_INLINE_ void set_max_bias(real_t p_bias) { max_bias = p_bias; }
 	_FORCE_INLINE_ real_t get_max_bias() const { return max_bias; }
 
-	virtual bool setup(real_t p_step) { return false; }
-	virtual void solve(real_t p_step) {}
+	virtual bool setup(real_t p_step) override { return false; }
+	virtual bool pre_solve(real_t p_step) override { return false; }
+	virtual void solve(real_t p_step) override {}
 
 	void copy_settings_from(Joint2DSW *p_joint);
 
@@ -90,10 +95,11 @@ class PinJoint2DSW : public Joint2DSW {
 	real_t softness;
 
 public:
-	virtual PhysicsServer2D::JointType get_type() const { return PhysicsServer2D::JOINT_TYPE_PIN; }
+	virtual PhysicsServer2D::JointType get_type() const override { return PhysicsServer2D::JOINT_TYPE_PIN; }
 
-	virtual bool setup(real_t p_step);
-	virtual void solve(real_t p_step);
+	virtual bool setup(real_t p_step) override;
+	virtual bool pre_solve(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
 
 	void set_param(PhysicsServer2D::PinJointParam p_param, real_t p_value);
 	real_t get_param(PhysicsServer2D::PinJointParam p_param) const;
@@ -126,10 +132,11 @@ class GrooveJoint2DSW : public Joint2DSW {
 	bool correct;
 
 public:
-	virtual PhysicsServer2D::JointType get_type() const { return PhysicsServer2D::JOINT_TYPE_GROOVE; }
+	virtual PhysicsServer2D::JointType get_type() const override { return PhysicsServer2D::JOINT_TYPE_GROOVE; }
 
-	virtual bool setup(real_t p_step);
-	virtual void solve(real_t p_step);
+	virtual bool setup(real_t p_step) override;
+	virtual bool pre_solve(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
 
 	GrooveJoint2DSW(const Vector2 &p_a_groove1, const Vector2 &p_a_groove2, const Vector2 &p_b_anchor, Body2DSW *p_body_a, Body2DSW *p_body_b);
 };
@@ -153,15 +160,17 @@ class DampedSpringJoint2DSW : public Joint2DSW {
 
 	Vector2 rA, rB;
 	Vector2 n;
+	Vector2 j;
 	real_t n_mass;
 	real_t target_vrn;
 	real_t v_coef;
 
 public:
-	virtual PhysicsServer2D::JointType get_type() const { return PhysicsServer2D::JOINT_TYPE_DAMPED_SPRING; }
+	virtual PhysicsServer2D::JointType get_type() const override { return PhysicsServer2D::JOINT_TYPE_DAMPED_SPRING; }
 
-	virtual bool setup(real_t p_step);
-	virtual void solve(real_t p_step);
+	virtual bool setup(real_t p_step) override;
+	virtual bool pre_solve(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
 
 	void set_param(PhysicsServer2D::DampedSpringParam p_param, real_t p_value);
 	real_t get_param(PhysicsServer2D::DampedSpringParam p_param) const;

servers/physics_2d/step_2d_sw.cpp

@@ -29,45 +29,59 @@
 /*************************************************************************/
 
 #include "step_2d_sw.h"
+
 #include "core/os/os.h"
 
 #define BODY_ISLAND_COUNT_RESERVE 128
 #define BODY_ISLAND_SIZE_RESERVE 512
 #define ISLAND_COUNT_RESERVE 128
 #define ISLAND_SIZE_RESERVE 512
+#define CONSTRAINT_COUNT_RESERVE 1024
 
 void Step2DSW::_populate_island(Body2DSW *p_body, LocalVector<Body2DSW *> &p_body_island, LocalVector<Constraint2DSW *> &p_constraint_island) {
 	p_body->set_island_step(_step);
-	p_body_island.push_back(p_body);
 
-	// Faster with reversed iterations.
-	for (const List<Pair<Constraint2DSW *, int>>::Element *E = p_body->get_constraint_list().back(); E; E = E->prev()) {
-		Constraint2DSW *c = (Constraint2DSW *)E->get().first;
-		if (c->get_island_step() == _step) {
-			continue; //already processed
+	if (p_body->get_mode() > PhysicsServer2D::BODY_MODE_KINEMATIC) {
+		// Only dynamic bodies are tested for activation.
+		p_body_island.push_back(p_body);
+	}
+
+	for (const List<Pair<Constraint2DSW *, int>>::Element *E = p_body->get_constraint_list().front(); E; E = E->next()) {
+		Constraint2DSW *constraint = (Constraint2DSW *)E->get().first;
+		if (constraint->get_island_step() == _step) {
+			continue; // Already processed.
 		}
-		c->set_island_step(_step);
-		p_constraint_island.push_back(c);
+		constraint->set_island_step(_step);
+		p_constraint_island.push_back(constraint);
+		all_constraints.push_back(constraint);
 
-		for (int i = 0; i < c->get_body_count(); i++) {
+		for (int i = 0; i < constraint->get_body_count(); i++) {
 			if (i == E->get().second) {
 				continue;
 			}
-			Body2DSW *b = c->get_body_ptr()[i];
-			if (b->get_island_step() == _step || b->get_mode() == PhysicsServer2D::BODY_MODE_STATIC || b->get_mode() == PhysicsServer2D::BODY_MODE_KINEMATIC) {
-				continue; //no go
+			Body2DSW *other_body = constraint->get_body_ptr()[i];
+			if (other_body->get_island_step() == _step) {
+				continue; // Already processed.
+			}
+			if (other_body->get_mode() == PhysicsServer2D::BODY_MODE_STATIC) {
+				continue; // Static bodies don't connect islands.
 			}
-			_populate_island(c->get_body_ptr()[i], p_body_island, p_constraint_island);
+			_populate_island(other_body, p_body_island, p_constraint_island);
 		}
 	}
 }
 
-void Step2DSW::_setup_island(LocalVector<Constraint2DSW *> &p_constraint_island, real_t p_delta) {
+void Step2DSW::_setup_contraint(uint32_t p_constraint_index, void *p_userdata) {
+	Constraint2DSW *constraint = all_constraints[p_constraint_index];
+	constraint->setup(delta);
+}
+
+void Step2DSW::_pre_solve_island(LocalVector<Constraint2DSW *> &p_constraint_island) const {
 	uint32_t constraint_count = p_constraint_island.size();
 	uint32_t valid_constraint_count = 0;
 	for (uint32_t constraint_index = 0; constraint_index < constraint_count; ++constraint_index) {
 		Constraint2DSW *constraint = p_constraint_island[constraint_index];
-		if (p_constraint_island[constraint_index]->setup(p_delta)) {
+		if (p_constraint_island[constraint_index]->pre_solve(delta)) {
 			// Keep this constraint for solving.
 			p_constraint_island[valid_constraint_count++] = constraint;
 		}
@@ -75,27 +89,25 @@ void Step2DSW::_setup_island(LocalVector<Constraint2DSW *> &p_constraint_island,
 	p_constraint_island.resize(valid_constraint_count);
 }
 
-void Step2DSW::_solve_island(LocalVector<Constraint2DSW *> &p_constraint_island, int p_iterations, real_t p_delta) {
-	for (int i = 0; i < p_iterations; i++) {
-		uint32_t constraint_count = p_constraint_island.size();
+void Step2DSW::_solve_island(uint32_t p_island_index, void *p_userdata) const {
+	const LocalVector<Constraint2DSW *> &constraint_island = constraint_islands[p_island_index];
+
+	for (int i = 0; i < iterations; i++) {
+		uint32_t constraint_count = constraint_island.size();
 		for (uint32_t constraint_index = 0; constraint_index < constraint_count; ++constraint_index) {
-			p_constraint_island[constraint_index]->solve(p_delta);
+			constraint_island[constraint_index]->solve(delta);
 		}
 	}
 }
 
-void Step2DSW::_check_suspend(const LocalVector<Body2DSW *> &p_body_island, real_t p_delta) {
+void Step2DSW::_check_suspend(LocalVector<Body2DSW *> &p_body_island) const {
 	bool can_sleep = true;
 
 	uint32_t body_count = p_body_island.size();
 	for (uint32_t body_index = 0; body_index < body_count; ++body_index) {
 		Body2DSW *body = p_body_island[body_index];
 
-		if (body->get_mode() == PhysicsServer2D::BODY_MODE_STATIC || body->get_mode() == PhysicsServer2D::BODY_MODE_KINEMATIC) {
-			continue; // Ignore for static.
-		}
-
-		if (!body->sleep_test(p_delta)) {
+		if (!body->sleep_test(delta)) {
 			can_sleep = false;
 		}
 	}
@@ -104,10 +116,6 @@ void Step2DSW::_check_suspend(const LocalVector<Body2DSW *> &p_body_island, real
 	for (uint32_t body_index = 0; body_index < body_count; ++body_index) {
 		Body2DSW *body = p_body_island[body_index];
 
-		if (body->get_mode() == PhysicsServer2D::BODY_MODE_STATIC || body->get_mode() == PhysicsServer2D::BODY_MODE_KINEMATIC) {
-			continue; // Ignore for static.
-		}
-
 		bool active = body->is_active();
 
 		if (active == can_sleep) {
@@ -121,6 +129,9 @@ void Step2DSW::step(Space2DSW *p_space, real_t p_delta, int p_iterations) {
 
 	p_space->setup(); //update inertias, etc
 
+	iterations = p_iterations;
+	delta = p_delta;
+
 	const SelfList<Body2DSW>::List *body_list = &p_space->get_active_body_list();
 
 	/* INTEGRATE FORCES */
@@ -145,12 +156,39 @@ void Step2DSW::step(Space2DSW *p_space, real_t p_delta, int p_iterations) {
 		profile_begtime = profile_endtime;
 	}
 
-	/* GENERATE CONSTRAINT ISLANDS */
+	/* GENERATE CONSTRAINT ISLANDS FOR MOVING AREAS */
+
+	uint32_t island_count = 0;
+
+	const SelfList<Area2DSW>::List &aml = p_space->get_moved_area_list();
+
+	while (aml.first()) {
+		for (const Set<Constraint2DSW *>::Element *E = aml.first()->self()->get_constraints().front(); E; E = E->next()) {
+			Constraint2DSW *constraint = E->get();
+			if (constraint->get_island_step() == _step) {
+				continue;
+			}
+			constraint->set_island_step(_step);
+
+			// Each constraint can be on a separate island for areas as there's no solving phase.
+			++island_count;
+			if (constraint_islands.size() < island_count) {
+				constraint_islands.resize(island_count);
+			}
+			LocalVector<Constraint2DSW *> &constraint_island = constraint_islands[island_count - 1];
+			constraint_island.clear();
+
+			all_constraints.push_back(constraint);
+			constraint_island.push_back(constraint);
+		}
+		p_space->area_remove_from_moved_list((SelfList<Area2DSW> *)aml.first()); //faster to remove here
+	}
+
+	/* GENERATE CONSTRAINT ISLANDS FOR ACTIVE RIGID BODIES */
 
 	b = body_list->first();
 
 	uint32_t body_island_count = 0;
-	uint32_t island_count = 0;
 
 	while (b) {
 		Body2DSW *body = b->self();
@@ -174,7 +212,9 @@ void Step2DSW::step(Space2DSW *p_space, real_t p_delta, int p_iterations) {
 
 			_populate_island(body, body_island, constraint_island);
 
-			body_islands.push_back(body_island);
+			if (body_island.is_empty()) {
+				--body_island_count;
+			}
 
 			if (constraint_island.is_empty()) {
 				--island_count;
@@ -185,37 +225,16 @@ void Step2DSW::step(Space2DSW *p_space, real_t p_delta, int p_iterations) {
 
 	p_space->set_island_count((int)island_count);
 
-	const SelfList<Area2DSW>::List &aml = p_space->get_moved_area_list();
-
-	while (aml.first()) {
-		for (const Set<Constraint2DSW *>::Element *E = aml.first()->self()->get_constraints().front(); E; E = E->next()) {
-			Constraint2DSW *c = E->get();
-			if (c->get_island_step() == _step) {
-				continue;
-			}
-			c->set_island_step(_step);
-			++island_count;
-			if (constraint_islands.size() < island_count) {
-				constraint_islands.resize(island_count);
-			}
-			LocalVector<Constraint2DSW *> &constraint_island = constraint_islands[island_count - 1];
-			constraint_island.clear();
-			constraint_island.push_back(c);
-		}
-		p_space->area_remove_from_moved_list((SelfList<Area2DSW> *)aml.first()); //faster to remove here
-	}
-
 	{ //profile
 		profile_endtime = OS::get_singleton()->get_ticks_usec();
 		p_space->set_elapsed_time(Space2DSW::ELAPSED_TIME_GENERATE_ISLANDS, profile_endtime - profile_begtime);
 		profile_begtime = profile_endtime;
 	}
 
-	/* SETUP CONSTRAINT ISLANDS */
+	/* SETUP CONSTRAINTS / PROCESS COLLISIONS */
 
-	for (uint32_t island_index = 0; island_index < island_count; ++island_index) {
-		_setup_island(constraint_islands[island_index], p_delta);
-	}
+	uint32_t total_contraint_count = all_constraints.size();
+	work_pool.do_work(total_contraint_count, this, &Step2DSW::_setup_contraint, nullptr);
 
 	{ //profile
 		profile_endtime = OS::get_singleton()->get_ticks_usec();
@@ -223,10 +242,21 @@ void Step2DSW::step(Space2DSW *p_space, real_t p_delta, int p_iterations) {
 		profile_begtime = profile_endtime;
 	}
 
-	/* SOLVE CONSTRAINT ISLANDS */
+	/* PRE-SOLVE CONSTRAINT ISLANDS */
 
+	// Warning: This doesn't run on threads, because it involves thread-unsafe processing.
 	for (uint32_t island_index = 0; island_index < island_count; ++island_index) {
-		_solve_island(constraint_islands[island_index], p_iterations, p_delta);
+		_pre_solve_island(constraint_islands[island_index]);
+	}
+
+	/* SOLVE CONSTRAINT ISLANDS */
+
+	// Warning: _solve_island modifies the constraint islands for optimization purpose,
+	// their content is not reliable after these calls and shouldn't be used anymore.
+	if (island_count > 1) {
+		work_pool.do_work(island_count, this, &Step2DSW::_solve_island, nullptr);
+	} else if (island_count > 0) {
+		_solve_island(0);
 	}
 
 	{ //profile
@@ -247,7 +277,7 @@ void Step2DSW::step(Space2DSW *p_space, real_t p_delta, int p_iterations) {
 	/* SLEEP / WAKE UP ISLANDS */
 
 	for (uint32_t island_index = 0; island_index < body_island_count; ++island_index) {
-		_check_suspend(body_islands[island_index], p_delta);
+		_check_suspend(body_islands[island_index]);
 	}
 
 	{ //profile
@@ -256,6 +286,8 @@ void Step2DSW::step(Space2DSW *p_space, real_t p_delta, int p_iterations) {
 		//profile_begtime=profile_endtime;
 	}
 
+	all_constraints.clear();
+
 	p_space->update();
 	p_space->unlock();
 	_step++;
@@ -266,4 +298,11 @@ Step2DSW::Step2DSW() {
 
 	body_islands.reserve(BODY_ISLAND_COUNT_RESERVE);
 	constraint_islands.reserve(ISLAND_COUNT_RESERVE);
+	all_constraints.reserve(CONSTRAINT_COUNT_RESERVE);
+
+	work_pool.init();
+}
+
+Step2DSW::~Step2DSW() {
+	work_pool.finish();
 }

servers/physics_2d/step_2d_sw.h

@@ -34,21 +34,30 @@
 #include "space_2d_sw.h"
 
 #include "core/templates/local_vector.h"
+#include "core/templates/thread_work_pool.h"
 
 class Step2DSW {
 	uint64_t _step;
 
+	int iterations = 0;
+	real_t delta = 0.0;
+
+	ThreadWorkPool work_pool;
+
 	LocalVector<LocalVector<Body2DSW *>> body_islands;
 	LocalVector<LocalVector<Constraint2DSW *>> constraint_islands;
+	LocalVector<Constraint2DSW *> all_constraints;
 
 	void _populate_island(Body2DSW *p_body, LocalVector<Body2DSW *> &p_body_island, LocalVector<Constraint2DSW *> &p_constraint_island);
-	void _setup_island(LocalVector<Constraint2DSW *> &p_constraint_island, real_t p_delta);
-	void _solve_island(LocalVector<Constraint2DSW *> &p_constraint_island, int p_iterations, real_t p_delta);
-	void _check_suspend(const LocalVector<Body2DSW *> &p_body_island, real_t p_delta);
+	void _setup_contraint(uint32_t p_constraint_index, void *p_userdata = nullptr);
+	void _pre_solve_island(LocalVector<Constraint2DSW *> &p_constraint_island) const;
+	void _solve_island(uint32_t p_island_index, void *p_userdata = nullptr) const;
+	void _check_suspend(LocalVector<Body2DSW *> &p_body_island) const;
 
 public:
 	void step(Space2DSW *p_space, real_t p_delta, int p_iterations);
 	Step2DSW();
+	~Step2DSW();
 };
 
 #endif // STEP_2D_SW_H

servers/physics_3d/area_pair_3d_sw.cpp

@@ -40,31 +40,48 @@ bool AreaPair3DSW::setup(real_t p_step) {
 		result = true;
 	}
 
+	process_collision = false;
 	if (result != colliding) {
-		if (result) {
-			if (area->get_space_override_mode() != PhysicsServer3D::AREA_SPACE_OVERRIDE_DISABLED) {
-				body->add_area(area);
-			}
-			if (area->has_monitor_callback()) {
-				area->add_body_to_query(body, body_shape, area_shape);
-			}
-
-		} else {
-			if (area->get_space_override_mode() != PhysicsServer3D::AREA_SPACE_OVERRIDE_DISABLED) {
-				body->remove_area(area);
-			}
-			if (area->has_monitor_callback()) {
-				area->remove_body_from_query(body, body_shape, area_shape);
-			}
+		if (area->get_space_override_mode() != PhysicsServer3D::AREA_SPACE_OVERRIDE_DISABLED) {
+			process_collision = true;
+		} else if (area->has_monitor_callback()) {
+			process_collision = true;
 		}
 
 		colliding = result;
 	}
 
-	return false; //never do any post solving
+	return process_collision;
+}
+
+bool AreaPair3DSW::pre_solve(real_t p_step) {
+	if (!process_collision) {
+		return false;
+	}
+
+	if (colliding) {
+		if (area->get_space_override_mode() != PhysicsServer3D::AREA_SPACE_OVERRIDE_DISABLED) {
+			body->add_area(area);
+		}
+
+		if (area->has_monitor_callback()) {
+			area->add_body_to_query(body, body_shape, area_shape);
+		}
+	} else {
+		if (area->get_space_override_mode() != PhysicsServer3D::AREA_SPACE_OVERRIDE_DISABLED) {
+			body->remove_area(area);
+		}
+
+		if (area->has_monitor_callback()) {
+			area->remove_body_from_query(body, body_shape, area_shape);
+		}
+	}
+
+	return false; // Never do any post solving.
 }
 
 void AreaPair3DSW::solve(real_t p_step) {
+	// Nothing to do.
 }
 
 AreaPair3DSW::AreaPair3DSW(Body3DSW *p_body, int p_body_shape, Area3DSW *p_area, int p_area_shape) {
@@ -72,7 +89,6 @@ AreaPair3DSW::AreaPair3DSW(Body3DSW *p_body, int p_body_shape, Area3DSW *p_area,
 	area = p_area;
 	body_shape = p_body_shape;
 	area_shape = p_area_shape;
-	colliding = false;
 	body->add_constraint(this, 0);
 	area->add_constraint(this);
 	if (p_body->get_mode() == PhysicsServer3D::BODY_MODE_KINEMATIC) {
@@ -103,33 +119,48 @@ bool Area2Pair3DSW::setup(real_t p_step) {
 		result = true;
 	}
 
+	process_collision = false;
 	if (result != colliding) {
-		if (result) {
-			if (area_b->has_area_monitor_callback() && area_a->is_monitorable()) {
-				area_b->add_area_to_query(area_a, shape_a, shape_b);
-			}
-
-			if (area_a->has_area_monitor_callback() && area_b->is_monitorable()) {
-				area_a->add_area_to_query(area_b, shape_b, shape_a);
-			}
-
-		} else {
-			if (area_b->has_area_monitor_callback() && area_a->is_monitorable()) {
-				area_b->remove_area_from_query(area_a, shape_a, shape_b);
-			}
-
-			if (area_a->has_area_monitor_callback() && area_b->is_monitorable()) {
-				area_a->remove_area_from_query(area_b, shape_b, shape_a);
-			}
+		if (area_b->has_area_monitor_callback() && area_a->is_monitorable()) {
+			process_collision = true;
+		} else if (area_a->has_area_monitor_callback() && area_b->is_monitorable()) {
+			process_collision = true;
 		}
 
 		colliding = result;
 	}
 
-	return false; //never do any post solving
+	return process_collision;
+}
+
+bool Area2Pair3DSW::pre_solve(real_t p_step) {
+	if (!process_collision) {
+		return false;
+	}
+
+	if (colliding) {
+		if (area_b->has_area_monitor_callback() && area_a->is_monitorable()) {
+			area_b->add_area_to_query(area_a, shape_a, shape_b);
+		}
+
+		if (area_a->has_area_monitor_callback() && area_b->is_monitorable()) {
+			area_a->add_area_to_query(area_b, shape_b, shape_a);
+		}
+	} else {
+		if (area_b->has_area_monitor_callback() && area_a->is_monitorable()) {
+			area_b->remove_area_from_query(area_a, shape_a, shape_b);
+		}
+
+		if (area_a->has_area_monitor_callback() && area_b->is_monitorable()) {
+			area_a->remove_area_from_query(area_b, shape_b, shape_a);
+		}
+	}
+
+	return false; // Never do any post solving.
 }
 
 void Area2Pair3DSW::solve(real_t p_step) {
+	// Nothing to do.
 }
 
 Area2Pair3DSW::Area2Pair3DSW(Area3DSW *p_area_a, int p_shape_a, Area3DSW *p_area_b, int p_shape_b) {
@@ -137,7 +168,6 @@ Area2Pair3DSW::Area2Pair3DSW(Area3DSW *p_area_a, int p_shape_a, Area3DSW *p_area
 	area_b = p_area_b;
 	shape_a = p_shape_a;
 	shape_b = p_shape_b;
-	colliding = false;
 	area_a->add_constraint(this);
 	area_b->add_constraint(this);
 }

servers/physics_3d/area_pair_3d_sw.h

@@ -40,11 +40,13 @@ class AreaPair3DSW : public Constraint3DSW {
 	Area3DSW *area;
 	int body_shape;
 	int area_shape;
-	bool colliding;
+	bool colliding = false;
+	bool process_collision = false;
 
 public:
-	bool setup(real_t p_step);
-	void solve(real_t p_step);
+	virtual bool setup(real_t p_step) override;
+	virtual bool pre_solve(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
 
 	AreaPair3DSW(Body3DSW *p_body, int p_body_shape, Area3DSW *p_area, int p_area_shape);
 	~AreaPair3DSW();
@@ -55,11 +57,13 @@ class Area2Pair3DSW : public Constraint3DSW {
 	Area3DSW *area_b;
 	int shape_a;
 	int shape_b;
-	bool colliding;
+	bool colliding = false;
+	bool process_collision = false;
 
 public:
-	bool setup(real_t p_step);
-	void solve(real_t p_step);
+	virtual bool setup(real_t p_step) override;
+	virtual bool pre_solve(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
 
 	Area2Pair3DSW(Area3DSW *p_area_a, int p_shape_a, Area3DSW *p_area_b, int p_shape_b);
 	~Area2Pair3DSW();

servers/physics_3d/body_3d_sw.cpp

@@ -145,31 +145,17 @@ void Body3DSW::set_active(bool p_active) {
 	}
 
 	active = p_active;
-	if (!p_active) {
-		if (get_space()) {
-			get_space()->body_remove_from_active_list(&active_list);
-		}
-	} else {
+
+	if (active) {
 		if (mode == PhysicsServer3D::BODY_MODE_STATIC) {
-			return; //static bodies can't become active
-		}
-		if (get_space()) {
+			// Static bodies can't be active.
+			active = false;
+		} else if (get_space()) {
 			get_space()->body_add_to_active_list(&active_list);
 		}
-
-		//still_time=0;
+	} else if (get_space()) {
+		get_space()->body_remove_from_active_list(&active_list);
 	}
-	/*
-	if (!space)
-		return;
-
-	for(int i=0;i<get_shape_count();i++) {
-		Shape &s=shapes[i];
-		if (s.bpid>0) {
-			get_space()->get_broadphase()->set_active(s.bpid,active);
-		}
-	}
-*/
 }
 
 void Body3DSW::set_param(PhysicsServer3D::BodyParameter p_param, real_t p_value) {
@@ -392,13 +378,6 @@ void Body3DSW::set_space(Space3DSW *p_space) {
 		if (active) {
 			get_space()->body_add_to_active_list(&active_list);
 		}
-		/*
-		_update_queries();
-		if (is_active()) {
-			active=false;
-			set_active(true);
-		}
-		*/
 	}
 
 	first_integration = true;

servers/physics_3d/body_pair_3d_sw.cpp

@@ -212,14 +212,16 @@ real_t combine_friction(Body3DSW *A, Body3DSW *B) {
 }
 
 bool BodyPair3DSW::setup(real_t p_step) {
-	//cannot collide
+	dynamic_A = (A->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);
+	dynamic_B = (B->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);
+
 	if (!A->test_collision_mask(B) || A->has_exception(B->get_self()) || B->has_exception(A->get_self())) {
 		collided = false;
 		return false;
 	}
 
-	bool report_contacts_only = false;
-	if ((A->get_mode() <= PhysicsServer3D::BODY_MODE_KINEMATIC) && (B->get_mode() <= PhysicsServer3D::BODY_MODE_KINEMATIC)) {
+	report_contacts_only = false;
+	if (!dynamic_A && !dynamic_B) {
 		if ((A->get_max_contacts_reported() > 0) || (B->get_max_contacts_reported() > 0)) {
 			report_contacts_only = true;
 		} else {
@@ -237,7 +239,7 @@ bool BodyPair3DSW::setup(real_t p_step) {
 
 	validate_contacts();
 
-	Vector3 offset_A = A->get_transform().get_origin();
+	const Vector3 &offset_A = A->get_transform().get_origin();
 	Transform xform_Au = Transform(A->get_transform().basis, Vector3());
 	Transform xform_A = xform_Au * A->get_shape_transform(shape_A);
 
@@ -248,27 +250,37 @@ bool BodyPair3DSW::setup(real_t p_step) {
 	Shape3DSW *shape_A_ptr = A->get_shape(shape_A);
 	Shape3DSW *shape_B_ptr = B->get_shape(shape_B);
 
-	bool collided = CollisionSolver3DSW::solve_static(shape_A_ptr, xform_A, shape_B_ptr, xform_B, _contact_added_callback, this, &sep_axis);
-	this->collided = collided;
+	collided = CollisionSolver3DSW::solve_static(shape_A_ptr, xform_A, shape_B_ptr, xform_B, _contact_added_callback, this, &sep_axis);
 
 	if (!collided) {
 		//test ccd (currently just a raycast)
 
-		if (A->is_continuous_collision_detection_enabled() && A->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC && B->get_mode() <= PhysicsServer3D::BODY_MODE_KINEMATIC) {
+		if (A->is_continuous_collision_detection_enabled() && dynamic_A && !dynamic_B) {
 			_test_ccd(p_step, A, shape_A, xform_A, B, shape_B, xform_B);
 		}
 
-		if (B->is_continuous_collision_detection_enabled() && B->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC && A->get_mode() <= PhysicsServer3D::BODY_MODE_KINEMATIC) {
+		if (B->is_continuous_collision_detection_enabled() && dynamic_B && !dynamic_A) {
 			_test_ccd(p_step, B, shape_B, xform_B, A, shape_A, xform_A);
 		}
 
 		return false;
 	}
 
+	return true;
+}
+
+bool BodyPair3DSW::pre_solve(real_t p_step) {
+	if (!collided) {
+		return false;
+	}
+
 	real_t max_penetration = space->get_contact_max_allowed_penetration();
 
 	real_t bias = (real_t)0.3;
 
+	Shape3DSW *shape_A_ptr = A->get_shape(shape_A);
+	Shape3DSW *shape_B_ptr = B->get_shape(shape_B);
+
 	if (shape_A_ptr->get_custom_bias() || shape_B_ptr->get_custom_bias()) {
 		if (shape_A_ptr->get_custom_bias() == 0) {
 			bias = shape_B_ptr->get_custom_bias();
@@ -283,22 +295,26 @@ bool BodyPair3DSW::setup(real_t p_step) {
 
 	bool do_process = false;
 
+	const Basis &basis_A = A->get_transform().basis;
+	const Basis &basis_B = B->get_transform().basis;
+
 	for (int i = 0; i < contact_count; i++) {
 		Contact &c = contacts[i];
 		c.active = false;
 
-		Vector3 global_A = xform_Au.xform(c.local_A);
-		Vector3 global_B = xform_Bu.xform(c.local_B);
+		Vector3 global_A = basis_A.xform(c.local_A);
+		Vector3 global_B = basis_B.xform(c.local_B) + offset_B;
 
-		real_t depth = c.normal.dot(global_A - global_B);
+		Vector3 axis = global_A - global_B;
+		real_t depth = axis.dot(c.normal);
 
 		if (depth <= 0) {
 			continue;
 		}
 
 #ifdef DEBUG_ENABLED
-
 		if (space->is_debugging_contacts()) {
+			const Vector3 &offset_A = A->get_transform().get_origin();
 			space->add_debug_contact(global_A + offset_A);
 			space->add_debug_contact(global_B + offset_A);
 		}
@@ -338,8 +354,12 @@ bool BodyPair3DSW::setup(real_t p_step) {
 		c.depth = depth;
 
 		Vector3 j_vec = c.normal * c.acc_normal_impulse + c.acc_tangent_impulse;
-		A->apply_impulse(-j_vec, c.rA + A->get_center_of_mass());
-		B->apply_impulse(j_vec, c.rB + B->get_center_of_mass());
+		if (dynamic_A) {
+			A->apply_impulse(-j_vec, c.rA + A->get_center_of_mass());
+		}
+		if (dynamic_B) {
+			B->apply_impulse(j_vec, c.rB + B->get_center_of_mass());
+		}
 		c.acc_bias_impulse = 0;
 		c.acc_bias_impulse_center_of_mass = 0;
 
@@ -361,6 +381,8 @@ void BodyPair3DSW::solve(real_t p_step) {
 		return;
 	}
 
+	const real_t max_bias_av = MAX_BIAS_ROTATION / p_step;
+
 	for (int i = 0; i < contact_count; i++) {
 		Contact &c = contacts[i];
 		if (!c.active) {
@@ -384,8 +406,12 @@ void BodyPair3DSW::solve(real_t p_step) {
 
 			Vector3 jb = c.normal * (c.acc_bias_impulse - jbnOld);
 
-			A->apply_bias_impulse(-jb, c.rA + A->get_center_of_mass(), MAX_BIAS_ROTATION / p_step);
-			B->apply_bias_impulse(jb, c.rB + B->get_center_of_mass(), MAX_BIAS_ROTATION / p_step);
+			if (dynamic_A) {
+				A->apply_bias_impulse(-jb, c.rA + A->get_center_of_mass(), max_bias_av);
+			}
+			if (dynamic_B) {
+				B->apply_bias_impulse(jb, c.rB + B->get_center_of_mass(), max_bias_av);
+			}
 
 			crbA = A->get_biased_angular_velocity().cross(c.rA);
 			crbB = B->get_biased_angular_velocity().cross(c.rB);
@@ -400,8 +426,12 @@ void BodyPair3DSW::solve(real_t p_step) {
 
 				Vector3 jb_com = c.normal * (c.acc_bias_impulse_center_of_mass - jbnOld_com);
 
-				A->apply_bias_impulse(-jb_com, A->get_center_of_mass(), 0.0f);
-				B->apply_bias_impulse(jb_com, B->get_center_of_mass(), 0.0f);
+				if (dynamic_A) {
+					A->apply_bias_impulse(-jb_com, A->get_center_of_mass(), 0.0f);
+				}
+				if (dynamic_B) {
+					B->apply_bias_impulse(jb_com, B->get_center_of_mass(), 0.0f);
+				}
 			}
 
 			c.active = true;
@@ -421,8 +451,12 @@ void BodyPair3DSW::solve(real_t p_step) {
 
 			Vector3 j = c.normal * (c.acc_normal_impulse - jnOld);
 
-			A->apply_impulse(-j, c.rA + A->get_center_of_mass());
-			B->apply_impulse(j, c.rB + B->get_center_of_mass());
+			if (dynamic_A) {
+				A->apply_impulse(-j, c.rA + A->get_center_of_mass());
+			}
+			if (dynamic_B) {
+				B->apply_impulse(j, c.rB + B->get_center_of_mass());
+			}
 
 			c.active = true;
 		}
@@ -464,8 +498,12 @@ void BodyPair3DSW::solve(real_t p_step) {
 
 			jt = c.acc_tangent_impulse - jtOld;
 
-			A->apply_impulse(-jt, c.rA + A->get_center_of_mass());
-			B->apply_impulse(jt, c.rB + B->get_center_of_mass());
+			if (dynamic_A) {
+				A->apply_impulse(-jt, c.rA + A->get_center_of_mass());
+			}
+			if (dynamic_B) {
+				B->apply_impulse(jt, c.rB + B->get_center_of_mass());
+			}
 
 			c.active = true;
 		}
@@ -481,8 +519,6 @@ BodyPair3DSW::BodyPair3DSW(Body3DSW *p_A, int p_shape_A, Body3DSW *p_B, int p_sh
 	space = A->get_space();
 	A->add_constraint(this, 0);
 	B->add_constraint(this, 1);
-	contact_count = 0;
-	collided = false;
 }
 
 BodyPair3DSW::~BodyPair3DSW() {
@@ -564,6 +600,8 @@ void BodySoftBodyPair3DSW::validate_contacts() {
 }
 
 bool BodySoftBodyPair3DSW::setup(real_t p_step) {
+	body_dynamic = (body->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);
+
 	if (!body->test_collision_mask(soft_body) || body->has_exception(soft_body->get_self()) || soft_body->has_exception(body->get_self())) {
 		collided = false;
 		return false;
@@ -585,12 +623,22 @@ bool BodySoftBodyPair3DSW::setup(real_t p_step) {
 	Shape3DSW *shape_A_ptr = body->get_shape(body_shape);
 	Shape3DSW *shape_B_ptr = soft_body->get_shape(0);
 
-	bool collided = CollisionSolver3DSW::solve_static(shape_A_ptr, xform_A, shape_B_ptr, xform_B, _contact_added_callback, this, &sep_axis);
-	this->collided = collided;
+	collided = CollisionSolver3DSW::solve_static(shape_A_ptr, xform_A, shape_B_ptr, xform_B, _contact_added_callback, this, &sep_axis);
+
+	return collided;
+}
+
+bool BodySoftBodyPair3DSW::pre_solve(real_t p_step) {
+	if (!collided) {
+		return false;
+	}
 
 	real_t max_penetration = space->get_contact_max_allowed_penetration();
 
 	real_t bias = (real_t)0.3;
+
+	Shape3DSW *shape_A_ptr = body->get_shape(body_shape);
+
 	if (shape_A_ptr->get_custom_bias()) {
 		bias = shape_A_ptr->get_custom_bias();
 	}
@@ -599,6 +647,8 @@ bool BodySoftBodyPair3DSW::setup(real_t p_step) {
 
 	bool do_process = false;
 
+	const Transform &transform_A = body->get_transform();
+
 	uint32_t contact_count = contacts.size();
 	for (uint32_t contact_index = 0; contact_index < contact_count; ++contact_index) {
 		Contact &c = contacts[contact_index];
@@ -609,10 +659,10 @@ bool BodySoftBodyPair3DSW::setup(real_t p_step) {
 			continue;
 		}
 
-		Vector3 global_A = xform_Au.xform(c.local_A);
+		Vector3 global_A = transform_A.xform(c.local_A);
 		Vector3 global_B = soft_body->get_node_position(c.index_B) + c.local_B;
-
-		real_t depth = c.normal.dot(global_A - global_B);
+		Vector3 axis = global_A - global_B;
+		real_t depth = axis.dot(c.normal);
 
 		if (depth <= 0) {
 			continue;
@@ -629,7 +679,7 @@ bool BodySoftBodyPair3DSW::setup(real_t p_step) {
 		}
 #endif
 
-		c.rA = global_A - xform_Au.origin - body->get_center_of_mass();
+		c.rA = global_A - transform_A.origin - body->get_center_of_mass();
 		c.rB = global_B;
 
 		if (body->can_report_contacts()) {
@@ -637,7 +687,7 @@ bool BodySoftBodyPair3DSW::setup(real_t p_step) {
 			body->add_contact(global_A, -c.normal, depth, body_shape, global_B, 0, soft_body->get_instance_id(), soft_body->get_self(), crA);
 		}
 
-		if (body->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC) {
+		if (body_dynamic) {
 			body->set_active(true);
 		}
 
@@ -651,7 +701,9 @@ bool BodySoftBodyPair3DSW::setup(real_t p_step) {
 		c.depth = depth;
 
 		Vector3 j_vec = c.normal * c.acc_normal_impulse + c.acc_tangent_impulse;
-		body->apply_impulse(-j_vec, c.rA + body->get_center_of_mass());
+		if (body_dynamic) {
+			body->apply_impulse(-j_vec, c.rA + body->get_center_of_mass());
+		}
 		soft_body->apply_node_impulse(c.index_B, j_vec);
 		c.acc_bias_impulse = 0;
 		c.acc_bias_impulse_center_of_mass = 0;
@@ -675,6 +727,8 @@ void BodySoftBodyPair3DSW::solve(real_t p_step) {
 		return;
 	}
 
+	const real_t max_bias_av = MAX_BIAS_ROTATION / p_step;
+
 	uint32_t contact_count = contacts.size();
 	for (uint32_t contact_index = 0; contact_index < contact_count; ++contact_index) {
 		Contact &c = contacts[contact_index];
@@ -697,7 +751,9 @@ void BodySoftBodyPair3DSW::solve(real_t p_step) {
 
 			Vector3 jb = c.normal * (c.acc_bias_impulse - jbnOld);
 
-			body->apply_bias_impulse(-jb, c.rA + body->get_center_of_mass(), MAX_BIAS_ROTATION / p_step);
+			if (body_dynamic) {
+				body->apply_bias_impulse(-jb, c.rA + body->get_center_of_mass(), max_bias_av);
+			}
 			soft_body->apply_node_bias_impulse(c.index_B, jb);
 
 			crbA = body->get_biased_angular_velocity().cross(c.rA);
@@ -712,7 +768,9 @@ void BodySoftBodyPair3DSW::solve(real_t p_step) {
 
 				Vector3 jb_com = c.normal * (c.acc_bias_impulse_center_of_mass - jbnOld_com);
 
-				body->apply_bias_impulse(-jb_com, body->get_center_of_mass(), 0.0f);
+				if (body_dynamic) {
+					body->apply_bias_impulse(-jb_com, body->get_center_of_mass(), 0.0f);
+				}
 				soft_body->apply_node_bias_impulse(c.index_B, jb_com);
 			}
 
@@ -732,7 +790,9 @@ void BodySoftBodyPair3DSW::solve(real_t p_step) {
 
 			Vector3 j = c.normal * (c.acc_normal_impulse - jnOld);
 
-			body->apply_impulse(-j, c.rA + body->get_center_of_mass());
+			if (body_dynamic) {
+				body->apply_impulse(-j, c.rA + body->get_center_of_mass());
+			}
 			soft_body->apply_node_impulse(c.index_B, j);
 
 			c.active = true;
@@ -773,7 +833,9 @@ void BodySoftBodyPair3DSW::solve(real_t p_step) {
 
 			jt = c.acc_tangent_impulse - jtOld;
 
-			body->apply_impulse(-jt, c.rA + body->get_center_of_mass());
+			if (body_dynamic) {
+				body->apply_impulse(-jt, c.rA + body->get_center_of_mass());
+			}
 			soft_body->apply_node_impulse(c.index_B, jt);
 
 			c.active = true;
@@ -781,7 +843,8 @@ void BodySoftBodyPair3DSW::solve(real_t p_step) {
 	}
 }
 
-BodySoftBodyPair3DSW::BodySoftBodyPair3DSW(Body3DSW *p_A, int p_shape_A, SoftBody3DSW *p_B) {
+BodySoftBodyPair3DSW::BodySoftBodyPair3DSW(Body3DSW *p_A, int p_shape_A, SoftBody3DSW *p_B) :
+		BodyContact3DSW(&body, 1) {
 	body = p_A;
 	soft_body = p_B;
 	body_shape = p_shape_A;

servers/physics_3d/body_pair_3d_sw.h

@@ -57,9 +57,9 @@ protected:
 	};
 
 	Vector3 sep_axis;
-	bool collided;
+	bool collided = false;
 
-	Space3DSW *space;
+	Space3DSW *space = nullptr;
 
 	BodyContact3DSW(Body3DSW **p_body_ptr = nullptr, int p_body_count = 0) :
 			Constraint3DSW(p_body_ptr, p_body_count) {
@@ -77,16 +77,21 @@ class BodyPair3DSW : public BodyContact3DSW {
 			Body3DSW *B;
 		};
 
-		Body3DSW *_arr[2];
+		Body3DSW *_arr[2] = { nullptr, nullptr };
 	};
 
-	int shape_A;
-	int shape_B;
+	int shape_A = 0;
+	int shape_B = 0;
+
+	bool dynamic_A = false;
+	bool dynamic_B = false;
+
+	bool report_contacts_only = false;
 
 	Vector3 offset_B; //use local A coordinates to avoid numerical issues on collision detection
 
 	Contact contacts[MAX_CONTACTS];
-	int contact_count;
+	int contact_count = 0;
 
 	static void _contact_added_callback(const Vector3 &p_point_A, int p_index_A, const Vector3 &p_point_B, int p_index_B, void *p_userdata);
 
@@ -96,18 +101,21 @@ class BodyPair3DSW : public BodyContact3DSW {
 	bool _test_ccd(real_t p_step, Body3DSW *p_A, int p_shape_A, const Transform &p_xform_A, Body3DSW *p_B, int p_shape_B, const Transform &p_xform_B);
 
 public:
-	bool setup(real_t p_step);
-	void solve(real_t p_step);
+	virtual bool setup(real_t p_step) override;
+	virtual bool pre_solve(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
 
 	BodyPair3DSW(Body3DSW *p_A, int p_shape_A, Body3DSW *p_B, int p_shape_B);
 	~BodyPair3DSW();
 };
 
 class BodySoftBodyPair3DSW : public BodyContact3DSW {
-	Body3DSW *body;
-	SoftBody3DSW *soft_body;
+	Body3DSW *body = nullptr;
+	SoftBody3DSW *soft_body = nullptr;
 
-	int body_shape;
+	int body_shape = 0;
+
+	bool body_dynamic = false;
 
 	LocalVector<Contact> contacts;
 
@@ -118,8 +126,12 @@ class BodySoftBodyPair3DSW : public BodyContact3DSW {
 	void validate_contacts();
 
 public:
-	bool setup(real_t p_step);
-	void solve(real_t p_step);
+	virtual bool setup(real_t p_step) override;
+	virtual bool pre_solve(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
+
+	virtual SoftBody3DSW *get_soft_body_ptr(int p_index) const override { return soft_body; }
+	virtual int get_soft_body_count() const override { return 1; }
 
 	BodySoftBodyPair3DSW(Body3DSW *p_A, int p_shape_A, SoftBody3DSW *p_B);
 	~BodySoftBodyPair3DSW();

servers/physics_3d/constraint_3d_sw.h

@@ -31,7 +31,8 @@
 #ifndef CONSTRAINT_SW_H
 #define CONSTRAINT_SW_H
 
-#include "body_3d_sw.h"
+class Body3DSW;
+class SoftBody3DSW;
 
 class Constraint3DSW {
 	Body3DSW **_body_ptr;
@@ -61,6 +62,9 @@ public:
 	_FORCE_INLINE_ Body3DSW **get_body_ptr() const { return _body_ptr; }
 	_FORCE_INLINE_ int get_body_count() const { return _body_count; }
 
+	virtual SoftBody3DSW *get_soft_body_ptr(int p_index) const { return nullptr; }
+	virtual int get_soft_body_count() const { return 0; }
+
 	_FORCE_INLINE_ void set_priority(int p_priority) { priority = p_priority; }
 	_FORCE_INLINE_ int get_priority() const { return priority; }
 
@@ -68,6 +72,7 @@ public:
 	_FORCE_INLINE_ bool is_disabled_collisions_between_bodies() const { return disabled_collisions_between_bodies; }
 
 	virtual bool setup(real_t p_step) = 0;
+	virtual bool pre_solve(real_t p_step) = 0;
 	virtual void solve(real_t p_step) = 0;
 
 	virtual ~Constraint3DSW() {}

servers/physics_3d/joints/cone_twist_joint_3d_sw.cpp

@@ -109,7 +109,10 @@ ConeTwistJoint3DSW::ConeTwistJoint3DSW(Body3DSW *rbA, Body3DSW *rbB, const Trans
 }
 
 bool ConeTwistJoint3DSW::setup(real_t p_timestep) {
-	if ((A->get_mode() <= PhysicsServer3D::BODY_MODE_KINEMATIC) && (B->get_mode() <= PhysicsServer3D::BODY_MODE_KINEMATIC)) {
+	dynamic_A = (A->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);
+	dynamic_B = (B->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);
+
+	if (!dynamic_A && !dynamic_B) {
 		return false;
 	}
 
@@ -265,8 +268,12 @@ void ConeTwistJoint3DSW::solve(real_t p_timestep) {
 			real_t impulse = depth * tau / p_timestep * jacDiagABInv - rel_vel * jacDiagABInv;
 			m_appliedImpulse += impulse;
 			Vector3 impulse_vector = normal * impulse;
-			A->apply_impulse(impulse_vector, pivotAInW - A->get_transform().origin);
-			B->apply_impulse(-impulse_vector, pivotBInW - B->get_transform().origin);
+			if (dynamic_A) {
+				A->apply_impulse(impulse_vector, pivotAInW - A->get_transform().origin);
+			}
+			if (dynamic_B) {
+				B->apply_impulse(-impulse_vector, pivotBInW - B->get_transform().origin);
+			}
 		}
 	}
 
@@ -287,8 +294,12 @@ void ConeTwistJoint3DSW::solve(real_t p_timestep) {
 
 			Vector3 impulse = m_swingAxis * impulseMag;
 
-			A->apply_torque_impulse(impulse);
-			B->apply_torque_impulse(-impulse);
+			if (dynamic_A) {
+				A->apply_torque_impulse(impulse);
+			}
+			if (dynamic_B) {
+				B->apply_torque_impulse(-impulse);
+			}
 		}
 
 		// solve twist limit
@@ -303,8 +314,12 @@ void ConeTwistJoint3DSW::solve(real_t p_timestep) {
 
 			Vector3 impulse = m_twistAxis * impulseMag;
 
-			A->apply_torque_impulse(impulse);
-			B->apply_torque_impulse(-impulse);
+			if (dynamic_A) {
+				A->apply_torque_impulse(impulse);
+			}
+			if (dynamic_B) {
+				B->apply_torque_impulse(-impulse);
+			}
 		}
 	}
 }

servers/physics_3d/joints/cone_twist_joint_3d_sw.h

@@ -102,10 +102,10 @@ public:
 	bool m_solveSwingLimit;
 
 public:
-	virtual PhysicsServer3D::JointType get_type() const { return PhysicsServer3D::JOINT_TYPE_CONE_TWIST; }
+	virtual PhysicsServer3D::JointType get_type() const override { return PhysicsServer3D::JOINT_TYPE_CONE_TWIST; }
 
-	virtual bool setup(real_t p_timestep);
-	virtual void solve(real_t p_timestep);
+	virtual bool setup(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
 
 	ConeTwistJoint3DSW(Body3DSW *rbA, Body3DSW *rbB, const Transform &rbAFrame, const Transform &rbBFrame);
 

servers/physics_3d/joints/generic_6dof_joint_3d_sw.cpp

@@ -82,7 +82,7 @@ int G6DOFRotationalLimitMotor3DSW::testLimitValue(real_t test_value) {
 
 real_t G6DOFRotationalLimitMotor3DSW::solveAngularLimits(
 		real_t timeStep, Vector3 &axis, real_t jacDiagABInv,
-		Body3DSW *body0, Body3DSW *body1) {
+		Body3DSW *body0, Body3DSW *body1, bool p_body0_dynamic, bool p_body1_dynamic) {
 	if (!needApplyTorques()) {
 		return 0.0f;
 	}
@@ -138,8 +138,10 @@ real_t G6DOFRotationalLimitMotor3DSW::solveAngularLimits(
 
 	Vector3 motorImp = clippedMotorImpulse * axis;
 
-	body0->apply_torque_impulse(motorImp);
-	if (body1) {
+	if (p_body0_dynamic) {
+		body0->apply_torque_impulse(motorImp);
+	}
+	if (body1 && p_body1_dynamic) {
 		body1->apply_torque_impulse(-motorImp);
 	}
 
@@ -154,6 +156,7 @@ real_t G6DOFTranslationalLimitMotor3DSW::solveLinearAxis(
 		real_t jacDiagABInv,
 		Body3DSW *body1, const Vector3 &pointInA,
 		Body3DSW *body2, const Vector3 &pointInB,
+		bool p_body1_dynamic, bool p_body2_dynamic,
 		int limit_index,
 		const Vector3 &axis_normal_on_a,
 		const Vector3 &anchorPos) {
@@ -205,8 +208,12 @@ real_t G6DOFTranslationalLimitMotor3DSW::solveLinearAxis(
 	normalImpulse = m_accumulatedImpulse[limit_index] - oldNormalImpulse;
 
 	Vector3 impulse_vector = axis_normal_on_a * normalImpulse;
-	body1->apply_impulse(impulse_vector, rel_pos1);
-	body2->apply_impulse(-impulse_vector, rel_pos2);
+	if (p_body1_dynamic) {
+		body1->apply_impulse(impulse_vector, rel_pos1);
+	}
+	if (p_body2_dynamic) {
+		body2->apply_impulse(-impulse_vector, rel_pos2);
+	}
 	return normalImpulse;
 }
 
@@ -303,7 +310,10 @@ bool Generic6DOFJoint3DSW::testAngularLimitMotor(int axis_index) {
 }
 
 bool Generic6DOFJoint3DSW::setup(real_t p_timestep) {
-	if ((A->get_mode() <= PhysicsServer3D::BODY_MODE_KINEMATIC) && (B->get_mode() <= PhysicsServer3D::BODY_MODE_KINEMATIC)) {
+	dynamic_A = (A->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);
+	dynamic_B = (B->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);
+
+	if (!dynamic_A && !dynamic_B) {
 		return false;
 	}
 
@@ -384,6 +394,7 @@ void Generic6DOFJoint3DSW::solve(real_t p_timestep) {
 					jacDiagABInv,
 					A, pointInA,
 					B, pointInB,
+					dynamic_A, dynamic_B,
 					i, linear_axis, m_AnchorPos);
 		}
 	}
@@ -398,7 +409,7 @@ void Generic6DOFJoint3DSW::solve(real_t p_timestep) {
 
 			angularJacDiagABInv = real_t(1.) / m_jacAng[i].getDiagonal();
 
-			m_angularLimits[i].solveAngularLimits(m_timeStep, angular_axis, angularJacDiagABInv, A, B);
+			m_angularLimits[i].solveAngularLimits(m_timeStep, angular_axis, angularJacDiagABInv, A, B, dynamic_A, dynamic_B);
 		}
 	}
 }

servers/physics_3d/joints/generic_6dof_joint_3d_sw.h

@@ -120,7 +120,7 @@ public:
 	int testLimitValue(real_t test_value);
 
 	//! apply the correction impulses for two bodies
-	real_t solveAngularLimits(real_t timeStep, Vector3 &axis, real_t jacDiagABInv, Body3DSW *body0, Body3DSW *body1);
+	real_t solveAngularLimits(real_t timeStep, Vector3 &axis, real_t jacDiagABInv, Body3DSW *body0, Body3DSW *body1, bool p_body0_dynamic, bool p_body1_dynamic);
 };
 
 class G6DOFTranslationalLimitMotor3DSW {
@@ -166,6 +166,7 @@ public:
 			real_t jacDiagABInv,
 			Body3DSW *body1, const Vector3 &pointInA,
 			Body3DSW *body2, const Vector3 &pointInB,
+			bool p_body1_dynamic, bool p_body2_dynamic,
 			int limit_index,
 			const Vector3 &axis_normal_on_a,
 			const Vector3 &anchorPos);
@@ -234,10 +235,10 @@ protected:
 public:
 	Generic6DOFJoint3DSW(Body3DSW *rbA, Body3DSW *rbB, const Transform &frameInA, const Transform &frameInB, bool useLinearReferenceFrameA);
 
-	virtual PhysicsServer3D::JointType get_type() const { return PhysicsServer3D::JOINT_TYPE_6DOF; }
+	virtual PhysicsServer3D::JointType get_type() const override { return PhysicsServer3D::JOINT_TYPE_6DOF; }
 
-	virtual bool setup(real_t p_timestep);
-	virtual void solve(real_t p_timestep);
+	virtual bool setup(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
 
 	//! Calcs global transform of the offsets
 	/*!

servers/physics_3d/joints/hinge_joint_3d_sw.cpp

@@ -155,7 +155,10 @@ HingeJoint3DSW::HingeJoint3DSW(Body3DSW *rbA, Body3DSW *rbB, const Vector3 &pivo
 }
 
 bool HingeJoint3DSW::setup(real_t p_step) {
-	if ((A->get_mode() <= PhysicsServer3D::BODY_MODE_KINEMATIC) && (B->get_mode() <= PhysicsServer3D::BODY_MODE_KINEMATIC)) {
+	dynamic_A = (A->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);
+	dynamic_B = (B->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);
+
+	if (!dynamic_A && !dynamic_B) {
 		return false;
 	}
 
@@ -279,8 +282,12 @@ void HingeJoint3DSW::solve(real_t p_step) {
 			real_t impulse = depth * tau / p_step * jacDiagABInv - rel_vel * jacDiagABInv;
 			m_appliedImpulse += impulse;
 			Vector3 impulse_vector = normal * impulse;
-			A->apply_impulse(impulse_vector, pivotAInW - A->get_transform().origin);
-			B->apply_impulse(-impulse_vector, pivotBInW - B->get_transform().origin);
+			if (dynamic_A) {
+				A->apply_impulse(impulse_vector, pivotAInW - A->get_transform().origin);
+			}
+			if (dynamic_B) {
+				B->apply_impulse(-impulse_vector, pivotBInW - B->get_transform().origin);
+			}
 		}
 	}
 
@@ -322,8 +329,12 @@ void HingeJoint3DSW::solve(real_t p_step) {
 				angularError *= (real_t(1.) / denom2) * relaxation;
 			}
 
-			A->apply_torque_impulse(-velrelOrthog + angularError);
-			B->apply_torque_impulse(velrelOrthog - angularError);
+			if (dynamic_A) {
+				A->apply_torque_impulse(-velrelOrthog + angularError);
+			}
+			if (dynamic_B) {
+				B->apply_torque_impulse(velrelOrthog - angularError);
+			}
 
 			// solve limit
 			if (m_solveLimit) {
@@ -337,8 +348,12 @@ void HingeJoint3DSW::solve(real_t p_step) {
 				impulseMag = m_accLimitImpulse - temp;
 
 				Vector3 impulse = axisA * impulseMag * m_limitSign;
-				A->apply_torque_impulse(impulse);
-				B->apply_torque_impulse(-impulse);
+				if (dynamic_A) {
+					A->apply_torque_impulse(impulse);
+				}
+				if (dynamic_B) {
+					B->apply_torque_impulse(-impulse);
+				}
 			}
 		}
 
@@ -359,8 +374,12 @@ void HingeJoint3DSW::solve(real_t p_step) {
 			clippedMotorImpulse = clippedMotorImpulse < -m_maxMotorImpulse ? -m_maxMotorImpulse : clippedMotorImpulse;
 			Vector3 motorImp = clippedMotorImpulse * axisA;
 
-			A->apply_torque_impulse(motorImp + angularLimit);
-			B->apply_torque_impulse(-motorImp - angularLimit);
+			if (dynamic_A) {
+				A->apply_torque_impulse(motorImp + angularLimit);
+			}
+			if (dynamic_B) {
+				B->apply_torque_impulse(-motorImp - angularLimit);
+			}
 		}
 	}
 }

servers/physics_3d/joints/hinge_joint_3d_sw.h

@@ -96,10 +96,10 @@ class HingeJoint3DSW : public Joint3DSW {
 	real_t m_appliedImpulse;
 
 public:
-	virtual PhysicsServer3D::JointType get_type() const { return PhysicsServer3D::JOINT_TYPE_HINGE; }
+	virtual PhysicsServer3D::JointType get_type() const override { return PhysicsServer3D::JOINT_TYPE_HINGE; }
 
-	virtual bool setup(real_t p_step);
-	virtual void solve(real_t p_step);
+	virtual bool setup(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
 
 	real_t get_hinge_angle();
 

servers/physics_3d/joints/pin_joint_3d_sw.cpp

@@ -50,7 +50,10 @@ subject to the following restrictions:
 #include "pin_joint_3d_sw.h"
 
 bool PinJoint3DSW::setup(real_t p_step) {
-	if ((A->get_mode() <= PhysicsServer3D::BODY_MODE_KINEMATIC) && (B->get_mode() <= PhysicsServer3D::BODY_MODE_KINEMATIC)) {
+	dynamic_A = (A->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);
+	dynamic_B = (B->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);
+
+	if (!dynamic_A && !dynamic_B) {
 		return false;
 	}
 
@@ -123,8 +126,12 @@ void PinJoint3DSW::solve(real_t p_step) {
 
 		m_appliedImpulse += impulse;
 		Vector3 impulse_vector = normal * impulse;
-		A->apply_impulse(impulse_vector, pivotAInW - A->get_transform().origin);
-		B->apply_impulse(-impulse_vector, pivotBInW - B->get_transform().origin);
+		if (dynamic_A) {
+			A->apply_impulse(impulse_vector, pivotAInW - A->get_transform().origin);
+		}
+		if (dynamic_B) {
+			B->apply_impulse(-impulse_vector, pivotBInW - B->get_transform().origin);
+		}
 
 		normal[i] = 0;
 	}

servers/physics_3d/joints/pin_joint_3d_sw.h

@@ -74,10 +74,10 @@ class PinJoint3DSW : public Joint3DSW {
 	Vector3 m_pivotInB;
 
 public:
-	virtual PhysicsServer3D::JointType get_type() const { return PhysicsServer3D::JOINT_TYPE_PIN; }
+	virtual PhysicsServer3D::JointType get_type() const override { return PhysicsServer3D::JOINT_TYPE_PIN; }
 
-	virtual bool setup(real_t p_step);
-	virtual void solve(real_t p_step);
+	virtual bool setup(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
 
 	void set_param(PhysicsServer3D::PinJointParam p_param, real_t p_value);
 	real_t get_param(PhysicsServer3D::PinJointParam p_param) const;

servers/physics_3d/joints/slider_joint_3d_sw.cpp

@@ -127,7 +127,10 @@ SliderJoint3DSW::SliderJoint3DSW(Body3DSW *rbA, Body3DSW *rbB, const Transform &
 //-----------------------------------------------------------------------------
 
 bool SliderJoint3DSW::setup(real_t p_step) {
-	if ((A->get_mode() <= PhysicsServer3D::BODY_MODE_KINEMATIC) && (B->get_mode() <= PhysicsServer3D::BODY_MODE_KINEMATIC)) {
+	dynamic_A = (A->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);
+	dynamic_B = (B->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC);
+
+	if (!dynamic_A && !dynamic_B) {
 		return false;
 	}
 
@@ -200,8 +203,12 @@ void SliderJoint3DSW::solve(real_t p_step) {
 		// calcutate and apply impulse
 		real_t normalImpulse = softness * (restitution * depth / p_step - damping * rel_vel) * m_jacLinDiagABInv[i];
 		Vector3 impulse_vector = normal * normalImpulse;
-		A->apply_impulse(impulse_vector, m_relPosA);
-		B->apply_impulse(-impulse_vector, m_relPosB);
+		if (dynamic_A) {
+			A->apply_impulse(impulse_vector, m_relPosA);
+		}
+		if (dynamic_B) {
+			B->apply_impulse(-impulse_vector, m_relPosB);
+		}
 		if (m_poweredLinMotor && (!i)) { // apply linear motor
 			if (m_accumulatedLinMotorImpulse < m_maxLinMotorForce) {
 				real_t desiredMotorVel = m_targetLinMotorVelocity;
@@ -221,8 +228,12 @@ void SliderJoint3DSW::solve(real_t p_step) {
 				m_accumulatedLinMotorImpulse = new_acc;
 				// apply clamped impulse
 				impulse_vector = normal * normalImpulse;
-				A->apply_impulse(impulse_vector, m_relPosA);
-				B->apply_impulse(-impulse_vector, m_relPosB);
+				if (dynamic_A) {
+					A->apply_impulse(impulse_vector, m_relPosA);
+				}
+				if (dynamic_B) {
+					B->apply_impulse(-impulse_vector, m_relPosB);
+				}
 			}
 		}
 	}
@@ -256,8 +267,12 @@ void SliderJoint3DSW::solve(real_t p_step) {
 		angularError *= (real_t(1.) / denom2) * m_restitutionOrthoAng * m_softnessOrthoAng;
 	}
 	// apply impulse
-	A->apply_torque_impulse(-velrelOrthog + angularError);
-	B->apply_torque_impulse(velrelOrthog - angularError);
+	if (dynamic_A) {
+		A->apply_torque_impulse(-velrelOrthog + angularError);
+	}
+	if (dynamic_B) {
+		B->apply_torque_impulse(velrelOrthog - angularError);
+	}
 	real_t impulseMag;
 	//solve angular limits
 	if (m_solveAngLim) {
@@ -268,8 +283,12 @@ void SliderJoint3DSW::solve(real_t p_step) {
 		impulseMag *= m_kAngle * m_softnessDirAng;
 	}
 	Vector3 impulse = axisA * impulseMag;
-	A->apply_torque_impulse(impulse);
-	B->apply_torque_impulse(-impulse);
+	if (dynamic_A) {
+		A->apply_torque_impulse(impulse);
+	}
+	if (dynamic_B) {
+		B->apply_torque_impulse(-impulse);
+	}
 	//apply angular motor
 	if (m_poweredAngMotor) {
 		if (m_accumulatedAngMotorImpulse < m_maxAngMotorForce) {
@@ -294,8 +313,12 @@ void SliderJoint3DSW::solve(real_t p_step) {
 			m_accumulatedAngMotorImpulse = new_acc;
 			// apply clamped impulse
 			Vector3 motorImp = angImpulse * axisA;
-			A->apply_torque_impulse(motorImp);
-			B->apply_torque_impulse(-motorImp);
+			if (dynamic_A) {
+				A->apply_torque_impulse(motorImp);
+			}
+			if (dynamic_B) {
+				B->apply_torque_impulse(-motorImp);
+			}
 		}
 	}
 } // SliderJointSW::solveConstraint()

servers/physics_3d/joints/slider_joint_3d_sw.h

@@ -240,10 +240,10 @@ public:
 	void set_param(PhysicsServer3D::SliderJointParam p_param, real_t p_value);
 	real_t get_param(PhysicsServer3D::SliderJointParam p_param) const;
 
-	bool setup(real_t p_step);
-	void solve(real_t p_step);
+	virtual bool setup(real_t p_step) override;
+	virtual void solve(real_t p_step) override;
 
-	virtual PhysicsServer3D::JointType get_type() const { return PhysicsServer3D::JOINT_TYPE_SLIDER; }
+	virtual PhysicsServer3D::JointType get_type() const override { return PhysicsServer3D::JOINT_TYPE_SLIDER; }
 };
 
 #endif // SLIDER_JOINT_SW_H

servers/physics_3d/joints_3d_sw.h

@@ -35,9 +35,14 @@
 #include "constraint_3d_sw.h"
 
 class Joint3DSW : public Constraint3DSW {
+protected:
+	bool dynamic_A = false;
+	bool dynamic_B = false;
+
 public:
-	virtual bool setup(real_t p_step) { return false; }
-	virtual void solve(real_t p_step) {}
+	virtual bool setup(real_t p_step) override { return false; }
+	virtual bool pre_solve(real_t p_step) override { return true; }
+	virtual void solve(real_t p_step) override {}
 
 	void copy_settings_from(Joint3DSW *p_joint) {
 		set_self(p_joint->get_self());

servers/physics_3d/soft_body_3d_sw.h

@@ -106,6 +106,8 @@ class SoftBody3DSW : public CollisionObject3DSW {
 
 	VSet<RID> exceptions;
 
+	uint64_t island_step = 0;
+
 public:
 	SoftBody3DSW();
 
@@ -124,6 +126,9 @@ public:
 	_FORCE_INLINE_ bool has_exception(const RID &p_exception) const { return exceptions.has(p_exception); }
 	_FORCE_INLINE_ const VSet<RID> &get_exceptions() const { return exceptions; }
 
+	_FORCE_INLINE_ uint64_t get_island_step() const { return island_step; }
+	_FORCE_INLINE_ void set_island_step(uint64_t p_step) { island_step = p_step; }
+
 	virtual void set_space(Space3DSW *p_space);
 
 	void set_mesh(const Ref<Mesh> &p_mesh);

servers/physics_3d/step_3d_sw.cpp

@@ -37,39 +37,90 @@
 #define BODY_ISLAND_SIZE_RESERVE 512
 #define ISLAND_COUNT_RESERVE 128
 #define ISLAND_SIZE_RESERVE 512
+#define CONSTRAINT_COUNT_RESERVE 1024
 
 void Step3DSW::_populate_island(Body3DSW *p_body, LocalVector<Body3DSW *> &p_body_island, LocalVector<Constraint3DSW *> &p_constraint_island) {
 	p_body->set_island_step(_step);
-	p_body_island.push_back(p_body);
 
-	// Faster with reversed iterations.
-	for (Map<Constraint3DSW *, int>::Element *E = p_body->get_constraint_map().back(); E; E = E->prev()) {
-		Constraint3DSW *c = (Constraint3DSW *)E->key();
-		if (c->get_island_step() == _step) {
-			continue; //already processed
+	if (p_body->get_mode() > PhysicsServer3D::BODY_MODE_KINEMATIC) {
+		// Only dynamic bodies are tested for activation.
+		p_body_island.push_back(p_body);
+	}
+
+	for (Map<Constraint3DSW *, int>::Element *E = p_body->get_constraint_map().front(); E; E = E->next()) {
+		Constraint3DSW *constraint = (Constraint3DSW *)E->key();
+		if (constraint->get_island_step() == _step) {
+			continue; // Already processed.
 		}
-		c->set_island_step(_step);
-		p_constraint_island.push_back(c);
+		constraint->set_island_step(_step);
+		p_constraint_island.push_back(constraint);
+
+		all_constraints.push_back(constraint);
 
-		for (int i = 0; i < c->get_body_count(); i++) {
+		// Find connected rigid bodies.
+		for (int i = 0; i < constraint->get_body_count(); i++) {
 			if (i == E->get()) {
 				continue;
 			}
-			Body3DSW *b = c->get_body_ptr()[i];
-			if (b->get_island_step() == _step || b->get_mode() == PhysicsServer3D::BODY_MODE_STATIC || b->get_mode() == PhysicsServer3D::BODY_MODE_KINEMATIC) {
-				continue; //no go
+			Body3DSW *other_body = constraint->get_body_ptr()[i];
+			if (other_body->get_island_step() == _step) {
+				continue; // Already processed.
+			}
+			if (other_body->get_mode() == PhysicsServer3D::BODY_MODE_STATIC) {
+				continue; // Static bodies don't connect islands.
+			}
+			_populate_island(other_body, p_body_island, p_constraint_island);
+		}
+
+		// Find connected soft bodies.
+		for (int i = 0; i < constraint->get_soft_body_count(); i++) {
+			SoftBody3DSW *soft_body = constraint->get_soft_body_ptr(i);
+			if (soft_body->get_island_step() == _step) {
+				continue; // Already processed.
 			}
-			_populate_island(c->get_body_ptr()[i], p_body_island, p_constraint_island);
+			_populate_island_soft_body(soft_body, p_body_island, p_constraint_island);
 		}
 	}
 }
 
-void Step3DSW::_setup_island(LocalVector<Constraint3DSW *> &p_constraint_island, real_t p_delta) {
+void Step3DSW::_populate_island_soft_body(SoftBody3DSW *p_soft_body, LocalVector<Body3DSW *> &p_body_island, LocalVector<Constraint3DSW *> &p_constraint_island) {
+	p_soft_body->set_island_step(_step);
+
+	for (Set<Constraint3DSW *>::Element *E = p_soft_body->get_constraints().front(); E; E = E->next()) {
+		Constraint3DSW *constraint = (Constraint3DSW *)E->get();
+		if (constraint->get_island_step() == _step) {
+			continue; // Already processed.
+		}
+		constraint->set_island_step(_step);
+		p_constraint_island.push_back(constraint);
+
+		all_constraints.push_back(constraint);
+
+		// Find connected rigid bodies.
+		for (int i = 0; i < constraint->get_body_count(); i++) {
+			Body3DSW *body = constraint->get_body_ptr()[i];
+			if (body->get_island_step() == _step) {
+				continue; // Already processed.
+			}
+			if (body->get_mode() == PhysicsServer3D::BODY_MODE_STATIC) {
+				continue; // Static bodies don't connect islands.
+			}
+			_populate_island(body, p_body_island, p_constraint_island);
+		}
+	}
+}
+
+void Step3DSW::_setup_contraint(uint32_t p_constraint_index, void *p_userdata) {
+	Constraint3DSW *constraint = all_constraints[p_constraint_index];
+	constraint->setup(delta);
+}
+
+void Step3DSW::_pre_solve_island(LocalVector<Constraint3DSW *> &p_constraint_island) const {
 	uint32_t constraint_count = p_constraint_island.size();
 	uint32_t valid_constraint_count = 0;
 	for (uint32_t constraint_index = 0; constraint_index < constraint_count; ++constraint_index) {
 		Constraint3DSW *constraint = p_constraint_island[constraint_index];
-		if (p_constraint_island[constraint_index]->setup(p_delta)) {
+		if (p_constraint_island[constraint_index]->pre_solve(delta)) {
 			// Keep this constraint for solving.
 			p_constraint_island[valid_constraint_count++] = constraint;
 		}
@@ -77,15 +128,17 @@ void Step3DSW::_setup_island(LocalVector<Constraint3DSW *> &p_constraint_island,
 	p_constraint_island.resize(valid_constraint_count);
 }
 
-void Step3DSW::_solve_island(LocalVector<Constraint3DSW *> &p_constraint_island, int p_iterations, real_t p_delta) {
+void Step3DSW::_solve_island(uint32_t p_island_index, void *p_userdata) {
+	LocalVector<Constraint3DSW *> &constraint_island = constraint_islands[p_island_index];
+
 	int current_priority = 1;
 
-	uint32_t constraint_count = p_constraint_island.size();
+	uint32_t constraint_count = constraint_island.size();
 	while (constraint_count > 0) {
-		for (int i = 0; i < p_iterations; i++) {
+		for (int i = 0; i < iterations; i++) {
 			// Go through all iterations.
 			for (uint32_t constraint_index = 0; constraint_index < constraint_count; ++constraint_index) {
-				p_constraint_island[constraint_index]->solve(p_delta);
+				constraint_island[constraint_index]->solve(delta);
 			}
 		}
 
@@ -93,28 +146,24 @@ void Step3DSW::_solve_island(LocalVector<Constraint3DSW *> &p_constraint_island,
 		uint32_t priority_constraint_count = 0;
 		++current_priority;
 		for (uint32_t constraint_index = 0; constraint_index < constraint_count; ++constraint_index) {
-			Constraint3DSW *constraint = p_constraint_island[constraint_index];
+			Constraint3DSW *constraint = constraint_island[constraint_index];
 			if (constraint->get_priority() >= current_priority) {
 				// Keep this constraint for the next iteration.
-				p_constraint_island[priority_constraint_count++] = constraint;
+				constraint_island[priority_constraint_count++] = constraint;
 			}
 		}
 		constraint_count = priority_constraint_count;
 	}
 }
 
-void Step3DSW::_check_suspend(const LocalVector<Body3DSW *> &p_body_island, real_t p_delta) {
+void Step3DSW::_check_suspend(const LocalVector<Body3DSW *> &p_body_island) const {
 	bool can_sleep = true;
 
 	uint32_t body_count = p_body_island.size();
 	for (uint32_t body_index = 0; body_index < body_count; ++body_index) {
 		Body3DSW *body = p_body_island[body_index];
 
-		if (body->get_mode() == PhysicsServer3D::BODY_MODE_STATIC || body->get_mode() == PhysicsServer3D::BODY_MODE_KINEMATIC) {
-			continue; // Ignore for static.
-		}
-
-		if (!body->sleep_test(p_delta)) {
+		if (!body->sleep_test(delta)) {
 			can_sleep = false;
 		}
 	}
@@ -123,10 +172,6 @@ void Step3DSW::_check_suspend(const LocalVector<Body3DSW *> &p_body_island, real
 	for (uint32_t body_index = 0; body_index < body_count; ++body_index) {
 		Body3DSW *body = p_body_island[body_index];
 
-		if (body->get_mode() == PhysicsServer3D::BODY_MODE_STATIC || body->get_mode() == PhysicsServer3D::BODY_MODE_KINEMATIC) {
-			continue; // Ignore for static.
-		}
-
 		bool active = body->is_active();
 
 		if (active == can_sleep) {
@@ -140,6 +185,9 @@ void Step3DSW::step(Space3DSW *p_space, real_t p_delta, int p_iterations) {
 
 	p_space->setup(); //update inertias, etc
 
+	iterations = p_iterations;
+	delta = p_delta;
+
 	const SelfList<Body3DSW>::List *body_list = &p_space->get_active_body_list();
 
 	const SelfList<SoftBody3DSW>::List *soft_body_list = &p_space->get_active_soft_body_list();
@@ -175,12 +223,39 @@ void Step3DSW::step(Space3DSW *p_space, real_t p_delta, int p_iterations) {
 		profile_begtime = profile_endtime;
 	}
 
-	/* GENERATE CONSTRAINT ISLANDS */
+	/* GENERATE CONSTRAINT ISLANDS FOR MOVING AREAS */
+
+	uint32_t island_count = 0;
+
+	const SelfList<Area3DSW>::List &aml = p_space->get_moved_area_list();
+
+	while (aml.first()) {
+		for (const Set<Constraint3DSW *>::Element *E = aml.first()->self()->get_constraints().front(); E; E = E->next()) {
+			Constraint3DSW *constraint = E->get();
+			if (constraint->get_island_step() == _step) {
+				continue;
+			}
+			constraint->set_island_step(_step);
+
+			// Each constraint can be on a separate island for areas as there's no solving phase.
+			++island_count;
+			if (constraint_islands.size() < island_count) {
+				constraint_islands.resize(island_count);
+			}
+			LocalVector<Constraint3DSW *> &constraint_island = constraint_islands[island_count - 1];
+			constraint_island.clear();
+
+			all_constraints.push_back(constraint);
+			constraint_island.push_back(constraint);
+		}
+		p_space->area_remove_from_moved_list((SelfList<Area3DSW> *)aml.first()); //faster to remove here
+	}
+
+	/* GENERATE CONSTRAINT ISLANDS FOR ACTIVE RIGID BODIES */
 
 	b = body_list->first();
 
 	uint32_t body_island_count = 0;
-	uint32_t island_count = 0;
 
 	while (b) {
 		Body3DSW *body = b->self();
@@ -204,7 +279,9 @@ void Step3DSW::step(Space3DSW *p_space, real_t p_delta, int p_iterations) {
 
 			_populate_island(body, body_island, constraint_island);
 
-			body_islands.push_back(body_island);
+			if (body_island.is_empty()) {
+				--body_island_count;
+			}
 
 			if (constraint_island.is_empty()) {
 				--island_count;
@@ -213,58 +290,54 @@ void Step3DSW::step(Space3DSW *p_space, real_t p_delta, int p_iterations) {
 		b = b->next();
 	}
 
-	p_space->set_island_count((int)island_count);
+	/* GENERATE CONSTRAINT ISLANDS FOR ACTIVE SOFT BODIES */
 
-	const SelfList<Area3DSW>::List &aml = p_space->get_moved_area_list();
+	sb = soft_body_list->first();
+	while (sb) {
+		SoftBody3DSW *soft_body = sb->self();
 
-	while (aml.first()) {
-		for (const Set<Constraint3DSW *>::Element *E = aml.first()->self()->get_constraints().front(); E; E = E->next()) {
-			Constraint3DSW *c = E->get();
-			if (c->get_island_step() == _step) {
-				continue;
+		if (soft_body->get_island_step() != _step) {
+			++body_island_count;
+			if (body_islands.size() < body_island_count) {
+				body_islands.resize(body_island_count);
 			}
-			c->set_island_step(_step);
+			LocalVector<Body3DSW *> &body_island = body_islands[body_island_count - 1];
+			body_island.clear();
+			body_island.reserve(BODY_ISLAND_SIZE_RESERVE);
+
 			++island_count;
 			if (constraint_islands.size() < island_count) {
 				constraint_islands.resize(island_count);
 			}
 			LocalVector<Constraint3DSW *> &constraint_island = constraint_islands[island_count - 1];
 			constraint_island.clear();
-			constraint_island.push_back(c);
-		}
-		p_space->area_remove_from_moved_list((SelfList<Area3DSW> *)aml.first()); //faster to remove here
-	}
+			constraint_island.reserve(ISLAND_SIZE_RESERVE);
 
-	sb = soft_body_list->first();
-	while (sb) {
-		for (const Set<Constraint3DSW *>::Element *E = sb->self()->get_constraints().front(); E; E = E->next()) {
-			Constraint3DSW *c = E->get();
-			if (c->get_island_step() == _step) {
-				continue;
+			_populate_island_soft_body(soft_body, body_island, constraint_island);
+
+			if (body_island.is_empty()) {
+				--body_island_count;
 			}
-			c->set_island_step(_step);
-			++island_count;
-			if (constraint_islands.size() < island_count) {
-				constraint_islands.resize(island_count);
+
+			if (constraint_island.is_empty()) {
+				--island_count;
 			}
-			LocalVector<Constraint3DSW *> &constraint_island = constraint_islands[island_count - 1];
-			constraint_island.clear();
-			constraint_island.push_back(c);
 		}
 		sb = sb->next();
 	}
 
+	p_space->set_island_count((int)island_count);
+
 	{ //profile
 		profile_endtime = OS::get_singleton()->get_ticks_usec();
 		p_space->set_elapsed_time(Space3DSW::ELAPSED_TIME_GENERATE_ISLANDS, profile_endtime - profile_begtime);
 		profile_begtime = profile_endtime;
 	}
 
-	/* SETUP CONSTRAINT ISLANDS */
+	/* SETUP CONSTRAINTS / PROCESS COLLISIONS */
 
-	for (uint32_t island_index = 0; island_index < island_count; ++island_index) {
-		_setup_island(constraint_islands[island_index], p_delta);
-	}
+	uint32_t total_contraint_count = all_constraints.size();
+	work_pool.do_work(total_contraint_count, this, &Step3DSW::_setup_contraint, nullptr);
 
 	{ //profile
 		profile_endtime = OS::get_singleton()->get_ticks_usec();
@@ -272,12 +345,21 @@ void Step3DSW::step(Space3DSW *p_space, real_t p_delta, int p_iterations) {
 		profile_begtime = profile_endtime;
 	}
 
-	/* SOLVE CONSTRAINT ISLANDS */
+	/* PRE-SOLVE CONSTRAINT ISLANDS */
 
+	// Warning: This doesn't run on threads, because it involves thread-unsafe processing.
 	for (uint32_t island_index = 0; island_index < island_count; ++island_index) {
-		// Warning: _solve_island modifies the constraint islands for optimization purpose,
-		// their content is not reliable after these calls and shouldn't be used anymore.
-		_solve_island(constraint_islands[island_index], p_iterations, p_delta);
+		_pre_solve_island(constraint_islands[island_index]);
+	}
+
+	/* SOLVE CONSTRAINT ISLANDS */
+
+	// Warning: _solve_island modifies the constraint islands for optimization purpose,
+	// their content is not reliable after these calls and shouldn't be used anymore.
+	if (island_count > 1) {
+		work_pool.do_work(island_count, this, &Step3DSW::_solve_island, nullptr);
+	} else if (island_count > 0) {
+		_solve_island(0);
 	}
 
 	{ //profile
@@ -298,7 +380,7 @@ void Step3DSW::step(Space3DSW *p_space, real_t p_delta, int p_iterations) {
 	/* SLEEP / WAKE UP ISLANDS */
 
 	for (uint32_t island_index = 0; island_index < body_island_count; ++island_index) {
-		_check_suspend(body_islands[island_index], p_delta);
+		_check_suspend(body_islands[island_index]);
 	}
 
 	/* UPDATE SOFT BODY CONSTRAINTS */
@@ -315,6 +397,8 @@ void Step3DSW::step(Space3DSW *p_space, real_t p_delta, int p_iterations) {
 		profile_begtime = profile_endtime;
 	}
 
+	all_constraints.clear();
+
 	p_space->update();
 	p_space->unlock();
 	_step++;
@@ -325,4 +409,11 @@ Step3DSW::Step3DSW() {
 
 	body_islands.reserve(BODY_ISLAND_COUNT_RESERVE);
 	constraint_islands.reserve(ISLAND_COUNT_RESERVE);
+	all_constraints.reserve(CONSTRAINT_COUNT_RESERVE);
+
+	work_pool.init();
+}
+
+Step3DSW::~Step3DSW() {
+	work_pool.finish();
 }

servers/physics_3d/step_3d_sw.h

@@ -34,21 +34,31 @@
 #include "space_3d_sw.h"
 
 #include "core/templates/local_vector.h"
+#include "core/templates/thread_work_pool.h"
 
 class Step3DSW {
 	uint64_t _step;
 
+	int iterations = 0;
+	real_t delta = 0.0;
+
+	ThreadWorkPool work_pool;
+
 	LocalVector<LocalVector<Body3DSW *>> body_islands;
 	LocalVector<LocalVector<Constraint3DSW *>> constraint_islands;
+	LocalVector<Constraint3DSW *> all_constraints;
 
 	void _populate_island(Body3DSW *p_body, LocalVector<Body3DSW *> &p_body_island, LocalVector<Constraint3DSW *> &p_constraint_island);
-	void _setup_island(LocalVector<Constraint3DSW *> &p_constraint_island, real_t p_delta);
-	void _solve_island(LocalVector<Constraint3DSW *> &p_constraint_island, int p_iterations, real_t p_delta);
-	void _check_suspend(const LocalVector<Body3DSW *> &p_body_island, real_t p_delta);
+	void _populate_island_soft_body(SoftBody3DSW *p_soft_body, LocalVector<Body3DSW *> &p_body_island, LocalVector<Constraint3DSW *> &p_constraint_island);
+	void _setup_contraint(uint32_t p_constraint_index, void *p_userdata = nullptr);
+	void _pre_solve_island(LocalVector<Constraint3DSW *> &p_constraint_island) const;
+	void _solve_island(uint32_t p_island_index, void *p_userdata = nullptr);
+	void _check_suspend(const LocalVector<Body3DSW *> &p_body_island) const;
 
 public:
 	void step(Space3DSW *p_space, real_t p_delta, int p_iterations);
 	Step3DSW();
+	~Step3DSW();
 };
 
 #endif // STEP__SW_H