Merge pull request #76216 from belzecue/backport-PR55313

[3.x] Fix RigidDynamicBody gaining momentum with bounce

servers/physics/body_pair_sw.cpp

@@ -34,18 +34,6 @@
 #include "core/os/os.h"
 #include "space_sw.h"
 
-/*
-#define NO_ACCUMULATE_IMPULSES
-#define NO_SPLIT_IMPULSES
-
-#define NO_FRICTION
-*/
-
-#define NO_TANGENTIALS
-/* BODY PAIR */
-
-//#define ALLOWED_PENETRATION 0.01
-#define RELAXATION_TIMESTEPS 3
 #define MIN_VELOCITY 0.0001
 #define MAX_BIAS_ROTATION (Math_PI / 8)
 
@@ -335,9 +323,9 @@ bool BodyPairSW::setup(real_t p_step) {
 
 		c.bounce = combine_bounce(A, B);
 		if (c.bounce) {
-			Vector3 crA = A->get_angular_velocity().cross(c.rA);
-			Vector3 crB = B->get_angular_velocity().cross(c.rB);
-			Vector3 dv = B->get_linear_velocity() + crB - A->get_linear_velocity() - crA;
+			Vector3 crA = A->get_prev_angular_velocity().cross(c.rA);
+			Vector3 crB = B->get_prev_angular_velocity().cross(c.rB);
+			Vector3 dv = B->get_prev_linear_velocity() + crB - A->get_prev_linear_velocity() - crA;
 			//normal impule
 			c.bounce = c.bounce * dv.dot(c.normal);
 		}

servers/physics/body_sw.cpp

@@ -509,6 +509,9 @@ void BodySW::integrate_forces(real_t p_step) {
 		area_linear_damp=damp_area->get_linear_damp();
 	*/
 
+	prev_linear_velocity = linear_velocity;
+	prev_angular_velocity = angular_velocity;
+
 	Vector3 motion;
 	bool do_motion = false;
 

servers/physics/body_sw.h

@@ -44,6 +44,9 @@ class BodySW : public CollisionObjectSW {
 	Vector3 linear_velocity;
 	Vector3 angular_velocity;
 
+	Vector3 prev_linear_velocity;
+	Vector3 prev_angular_velocity;
+
 	Vector3 biased_linear_velocity;
 	Vector3 biased_angular_velocity;
 	real_t mass;
@@ -215,6 +218,9 @@ public:
 	_FORCE_INLINE_ void set_angular_velocity(const Vector3 &p_velocity) { angular_velocity = p_velocity; }
 	_FORCE_INLINE_ Vector3 get_angular_velocity() const { return angular_velocity; }
 
+	_FORCE_INLINE_ Vector3 get_prev_linear_velocity() const { return prev_linear_velocity; }
+	_FORCE_INLINE_ Vector3 get_prev_angular_velocity() const { return prev_angular_velocity; }
+
 	_FORCE_INLINE_ const Vector3 &get_biased_linear_velocity() const { return biased_linear_velocity; }
 	_FORCE_INLINE_ const Vector3 &get_biased_angular_velocity() const { return biased_angular_velocity; }
 

servers/physics_2d/body_2d_sw.cpp

@@ -461,6 +461,9 @@ void Body2DSW::integrate_forces(real_t p_step) {
 		area_linear_damp=damp_area->get_linear_damp();
 	*/
 
+	prev_linear_velocity = linear_velocity;
+	prev_angular_velocity = angular_velocity;
+
 	Vector2 motion;
 	bool do_motion = false;
 

servers/physics_2d/body_2d_sw.h

@@ -47,6 +47,9 @@ class Body2DSW : public CollisionObject2DSW {
 	Vector2 linear_velocity;
 	real_t angular_velocity;
 
+	Vector2 prev_linear_velocity;
+	real_t prev_angular_velocity = 0.0;
+
 	real_t linear_damp;
 	real_t angular_damp;
 	real_t gravity_scale;
@@ -195,6 +198,9 @@ public:
 	_FORCE_INLINE_ void set_angular_velocity(real_t p_velocity) { angular_velocity = p_velocity; }
 	_FORCE_INLINE_ real_t get_angular_velocity() const { return angular_velocity; }
 
+	_FORCE_INLINE_ Vector2 get_prev_linear_velocity() const { return prev_linear_velocity; }
+	_FORCE_INLINE_ real_t get_prev_angular_velocity() const { return prev_angular_velocity; }
+
 	_FORCE_INLINE_ void set_biased_linear_velocity(const Vector2 &p_velocity) { biased_linear_velocity = p_velocity; }
 	_FORCE_INLINE_ Vector2 get_biased_linear_velocity() const { return biased_linear_velocity; }
 

servers/physics_2d/body_pair_2d_sw.cpp

@@ -32,7 +32,6 @@
 #include "collision_solver_2d_sw.h"
 #include "space_2d_sw.h"
 
-#define POSITION_CORRECTION
 #define ACCUMULATE_IMPULSES
 
 void BodyPair2DSW::_add_contact(const Vector2 &p_point_A, const Vector2 &p_point_B, void *p_self) {
@@ -423,9 +422,9 @@ bool BodyPair2DSW::setup(real_t p_step) {
 
 		c.bounce = combine_bounce(A, B);
 		if (c.bounce) {
-			Vector2 crA(-A->get_angular_velocity() * c.rA.y, A->get_angular_velocity() * c.rA.x);
-			Vector2 crB(-B->get_angular_velocity() * c.rB.y, B->get_angular_velocity() * c.rB.x);
-			Vector2 dv = B->get_linear_velocity() + crB - A->get_linear_velocity() - crA;
+			Vector2 crA(-A->get_prev_angular_velocity() * c.rA.y, A->get_prev_angular_velocity() * c.rA.x);
+			Vector2 crB(-B->get_prev_angular_velocity() * c.rB.y, B->get_prev_angular_velocity() * c.rB.x);
+			Vector2 dv = B->get_prev_linear_velocity() + crB - A->get_prev_linear_velocity() - crA;
 			c.bounce = c.bounce * dv.dot(c.normal);
 		}