Warn against using non-uniform scale for 3D physics

Using non-uniform scale is known to cause many issues.
Add warnings to the editor and to the class reference.
Also remove the warning from SoftBody3D since it is
not relevant there: it simulates in global space.

doc/classes/AnimatableBody3D.xml

@@ -7,6 +7,7 @@
 		Animatable body for 3D physics.
 		An animatable body can't be moved by external forces or contacts, but can be moved by script or animation to affect other bodies in its path. It is ideal for implementing moving objects in the environment, such as moving platforms or doors.
 		When the body is moved manually, either from code or from an [AnimationPlayer] (with [member AnimationPlayer.playback_process_mode] set to [code]physics[/code]), the physics will automatically compute an estimate of their linear and angular velocity. This makes them very useful for moving platforms or other AnimationPlayer-controlled objects (like a door, a bridge that opens, etc).
+		[b]Warning:[/b] With a non-uniform scale this node will probably not function as expected. Please make sure to keep its scale uniform (i.e. the same on all axes), and change the size(s) of its collision shape(s) instead.
 	</description>
 	<tutorials>
 		<link title="3D Physics Tests Demo">https://godotengine.org/asset-library/asset/675</link>

doc/classes/Area3D.xml

@@ -7,6 +7,7 @@
 		3D area that detects [CollisionObject3D] nodes overlapping, entering, or exiting. Can also alter or override local physics parameters (gravity, damping) and route audio to custom audio buses.
 		To give the area its shape, add a [CollisionShape3D] or a [CollisionPolygon3D] node as a [i]direct[/i] child (or add multiple such nodes as direct children) of the area.
 		[b]Warning:[/b] See [ConcavePolygonShape3D] (also called "trimesh") for a warning about possibly unexpected behavior when using that shape for an area.
+		[b]Warning:[/b] With a non-uniform scale this node will probably not function as expected. Please make sure to keep its scale uniform (i.e. the same on all axes), and change the size(s) of its collision shape(s) instead.
 	</description>
 	<tutorials>
 		<link title="3D Platformer Demo">https://godotengine.org/asset-library/asset/125</link>

doc/classes/CharacterBody3D.xml

@@ -5,8 +5,9 @@
 	</brief_description>
 	<description>
 		Character bodies are special types of bodies that are meant to be user-controlled. They are not affected by physics at all; to other types of bodies, such as a rigid body, these are the same as a [AnimatableBody3D]. However, they have two main uses:
-		[b]Kinematic characters:[/b] Character bodies have an API for moving objects with walls and slopes detection ([method move_and_slide] method), in addition to collision detection (also done with [method PhysicsBody3D.move_and_collide]). This makes them really useful to implement characters that move in specific ways and collide with the world, but don't require advanced physics.
-		[b]Kinematic motion:[/b] Character bodies can also be used for kinematic motion (same functionality as [AnimatableBody3D]), which allows them to be moved by code and push other bodies on their path.
+		[i]Kinematic characters:[/i] Character bodies have an API for moving objects with walls and slopes detection ([method move_and_slide] method), in addition to collision detection (also done with [method PhysicsBody3D.move_and_collide]). This makes them really useful to implement characters that move in specific ways and collide with the world, but don't require advanced physics.
+		[i]Kinematic motion:[/i] Character bodies can also be used for kinematic motion (same functionality as [AnimatableBody3D]), which allows them to be moved by code and push other bodies on their path.
+		[b]Warning:[/b] With a non-uniform scale this node will probably not function as expected. Please make sure to keep its scale uniform (i.e. the same on all axes), and change the size(s) of its collision shape(s) instead.
 	</description>
 	<tutorials>
 		<link title="Kinematic character (2D)">$DOCS_URL/tutorials/physics/kinematic_character_2d.html</link>

doc/classes/CollisionObject3D.xml

@@ -5,6 +5,7 @@
 	</brief_description>
 	<description>
 		CollisionObject3D is the base class for physics objects. It can hold any number of collision [Shape3D]s. Each shape must be assigned to a [i]shape owner[/i]. The CollisionObject3D can have any number of shape owners. Shape owners are not nodes and do not appear in the editor, but are accessible through code using the [code]shape_owner_*[/code] methods.
+		[b]Warning:[/b] With a non-uniform scale this node will probably not function as expected. Please make sure to keep its scale uniform (i.e. the same on all axes), and change the size(s) of its collision shape(s) instead.
 	</description>
 	<tutorials>
 	</tutorials>

doc/classes/CollisionPolygon3D.xml

@@ -6,6 +6,7 @@
 	<description>
 		Allows editing a concave or convex collision polygon's vertices on a selected plane. Can also set a depth perpendicular to that plane. This class is only available in the editor. It will not appear in the scene tree at run-time. Creates several [ConvexPolygonShape3D]s at run-time to represent the original polygon using convex decomposition.
 		[b]Note:[/b] Since this is an editor-only helper, properties modified during gameplay will have no effect.
+		[b]Warning:[/b] A non-uniformly scaled CollisionPolygon3D node will probably not function as expected. Please make sure to keep its scale uniform (i.e. the same on all axes), and change its [member polygon]'s vertices instead.
 	</description>
 	<tutorials>
 	</tutorials>

doc/classes/CollisionShape3D.xml

@@ -6,6 +6,7 @@
 	<description>
 		Editor facility for creating and editing collision shapes in 3D space. Set the [member shape] property to configure the shape. [b]IMPORTANT[/b]: this is an Editor-only helper to create shapes, use [method CollisionObject3D.shape_owner_get_shape] to get the actual shape.
 		You can use this node to represent all sorts of collision shapes, for example, add this to an [Area3D] to give it a detection shape, or add it to a [PhysicsBody3D] to create a solid object.
+		[b]Warning:[/b] A non-uniformly scaled CollisionShape3D node will probably not function as expected. Please make sure to keep its scale uniform (i.e. the same on all axes), and change the size of its [member shape] resource instead.
 	</description>
 	<tutorials>
 		<link title="Physics introduction">$DOCS_URL/tutorials/physics/physics_introduction.html</link>

doc/classes/PhysicalBone3D.xml

@@ -3,6 +3,7 @@
 	<brief_description>
 	</brief_description>
 	<description>
+		[b]Warning:[/b] With a non-uniform scale this node will probably not function as expected. Please make sure to keep its scale uniform (i.e. the same on all axes), and change the size(s) of its collision shape(s) instead.
 	</description>
 	<tutorials>
 	</tutorials>

doc/classes/PhysicsBody3D.xml

@@ -4,7 +4,8 @@
 		Base class for all objects affected by physics in 3D space.
 	</brief_description>
 	<description>
-		PhysicsBody3D is an abstract base class for implementing a physics body. All *Body types inherit from it.
+		PhysicsBody3D is an abstract base class for implementing a physics body. All *Body3D types inherit from it.
+		[b]Warning:[/b] With a non-uniform scale this node will probably not function as expected. Please make sure to keep its scale uniform (i.e. the same on all axes), and change the size(s) of its collision shape(s) instead.
 	</description>
 	<tutorials>
 		<link title="Physics introduction">$DOCS_URL/tutorials/physics/physics_introduction.html</link>

doc/classes/RigidBody3D.xml

@@ -8,6 +8,7 @@
 		You can switch the body's behavior using [member lock_rotation], [member freeze], and [member freeze_mode].
 		[b]Note:[/b] Don't change a RigidBody3D's position every frame or very often. Sporadic changes work fine, but physics runs at a different granularity (fixed Hz) than usual rendering (process callback) and maybe even in a separate thread, so changing this from a process loop may result in strange behavior. If you need to directly affect the body's state, use [method _integrate_forces], which allows you to directly access the physics state.
 		If you need to override the default physics behavior, you can write a custom force integration function. See [member custom_integrator].
+		[b]Warning:[/b] With a non-uniform scale this node will probably not function as expected. Please make sure to keep its scale uniform (i.e. the same on all axes), and change the size(s) of its collision shape(s) instead.
 	</description>
 	<tutorials>
 		<link title="Physics introduction">$DOCS_URL/tutorials/physics/physics_introduction.html</link>

doc/classes/StaticBody3D.xml

@@ -7,8 +7,9 @@
 		Static body for 3D physics.
 		A static body is a simple body that doesn't move under physics simulation, i.e. it can't be moved by external forces or contacts but its transformation can still be updated manually by the user. It is ideal for implementing objects in the environment, such as walls or platforms. In contrast to [RigidBody3D], it doesn't consume any CPU resources as long as they don't move.
 		They have extra functionalities to move and affect other bodies:
-		[b]Static transform change:[/b] Static bodies can be moved by animation or script. In this case, they are just teleported and don't affect other bodies on their path.
-		[b]Constant velocity:[/b] When [member constant_linear_velocity] or [member constant_angular_velocity] is set, static bodies don't move themselves but affect touching bodies as if they were moving. This is useful for simulating conveyor belts or conveyor wheels.
+		[i]Static transform change:[/i] Static bodies can be moved by animation or script. In this case, they are just teleported and don't affect other bodies on their path.
+		[i]Constant velocity:[/i] When [member constant_linear_velocity] or [member constant_angular_velocity] is set, static bodies don't move themselves but affect touching bodies as if they were moving. This is useful for simulating conveyor belts or conveyor wheels.
+		[b]Warning:[/b] With a non-uniform scale this node will probably not function as expected. Please make sure to keep its scale uniform (i.e. the same on all axes), and change the size(s) of its collision shape(s) instead.
 	</description>
 	<tutorials>
 		<link title="3D Physics Tests Demo">https://godotengine.org/asset-library/asset/675</link>

doc/classes/VehicleBody3D.xml

@@ -7,6 +7,7 @@
 		This node implements all the physics logic needed to simulate a car. It is based on the raycast vehicle system commonly found in physics engines. You will need to add a [CollisionShape3D] for the main body of your vehicle and add [VehicleWheel3D] nodes for the wheels. You should also add a [MeshInstance3D] to this node for the 3D model of your car but this model should not include meshes for the wheels. You should control the vehicle by using the [member brake], [member engine_force], and [member steering] properties and not change the position or orientation of this node directly.
 		[b]Note:[/b] The origin point of your VehicleBody3D will determine the center of gravity of your vehicle so it is better to keep this low and move the [CollisionShape3D] and [MeshInstance3D] upwards.
 		[b]Note:[/b] This class has known issues and isn't designed to provide realistic 3D vehicle physics. If you want advanced vehicle physics, you will probably have to write your own physics integration using another [PhysicsBody3D] class.
+		[b]Warning:[/b] With a non-uniform scale this node will probably not function as expected. Please make sure to keep its scale uniform (i.e. the same on all axes), and change the size(s) of its collision shape(s) instead.
 	</description>
 	<tutorials>
 		<link title="3D Truck Town Demo">https://godotengine.org/asset-library/asset/524</link>

scene/3d/collision_object_3d.cpp

@@ -42,6 +42,11 @@ void CollisionObject3D::_notification(int p_what) {
 				}
 				_update_debug_shapes();
 			}
+#ifdef TOOLS_ENABLED
+			if (Engine::get_singleton()->is_editor_hint()) {
+				set_notify_local_transform(true); // Used for warnings and only in editor.
+			}
+#endif
 		} break;
 
 		case NOTIFICATION_EXIT_TREE: {
@@ -77,6 +82,14 @@ void CollisionObject3D::_notification(int p_what) {
 			_update_pickable();
 		} break;
 
+#ifdef TOOLS_ENABLED
+		case NOTIFICATION_LOCAL_TRANSFORM_CHANGED: {
+			if (Engine::get_singleton()->is_editor_hint()) {
+				update_configuration_warnings();
+			}
+		} break;
+#endif
+
 		case NOTIFICATION_TRANSFORM_CHANGED: {
 			if (only_update_transform_changes) {
 				return;
@@ -710,6 +723,11 @@ PackedStringArray CollisionObject3D::get_configuration_warnings() const {
 		warnings.push_back(RTR("This node has no shape, so it can't collide or interact with other objects.\nConsider adding a CollisionShape3D or CollisionPolygon3D as a child to define its shape."));
 	}
 
+	Vector3 scale = get_transform().get_basis().get_scale();
+	if (!(Math::is_zero_approx(scale.x - scale.y) && Math::is_zero_approx(scale.y - scale.z))) {
+		warnings.push_back(RTR("With a non-uniform scale this node will probably not function as expected.\nPlease make its scale uniform (i.e. the same on all axes), and change the size in children collision shapes instead."));
+	}
+
 	return warnings;
 }
 

scene/3d/collision_polygon_3d.cpp

@@ -104,6 +104,11 @@ void CollisionPolygon3D::_notification(int p_what) {
 			if (parent) {
 				_update_in_shape_owner(true);
 			}
+#ifdef TOOLS_ENABLED
+			if (Engine::get_singleton()->is_editor_hint()) {
+				update_configuration_warnings();
+			}
+#endif
 		} break;
 
 		case NOTIFICATION_UNPARENTED: {
@@ -171,13 +176,18 @@ PackedStringArray CollisionPolygon3D::get_configuration_warnings() const {
 	PackedStringArray warnings = Node::get_configuration_warnings();
 
 	if (!Object::cast_to<CollisionObject3D>(get_parent())) {
-		warnings.push_back(RTR("CollisionPolygon3D only serves to provide a collision shape to a CollisionObject3D derived node. Please only use it as a child of Area3D, StaticBody3D, RigidBody3D, CharacterBody3D, etc. to give them a shape."));
+		warnings.push_back(RTR("CollisionPolygon3D only serves to provide a collision shape to a CollisionObject3D derived node.\nPlease only use it as a child of Area3D, StaticBody3D, RigidBody3D, CharacterBody3D, etc. to give them a shape."));
 	}
 
 	if (polygon.is_empty()) {
 		warnings.push_back(RTR("An empty CollisionPolygon3D has no effect on collision."));
 	}
 
+	Vector3 scale = get_transform().get_basis().get_scale();
+	if (!(Math::is_zero_approx(scale.x - scale.y) && Math::is_zero_approx(scale.y - scale.z))) {
+		warnings.push_back(RTR("A non-uniformly scaled CollisionPolygon3D node will probably not function as expected.\nPlease make its scale uniform (i.e. the same on all axes), and change its polygon's vertices instead."));
+	}
+
 	return warnings;
 }
 

scene/3d/collision_shape_3d.cpp

@@ -98,6 +98,11 @@ void CollisionShape3D::_notification(int p_what) {
 			if (parent) {
 				_update_in_shape_owner(true);
 			}
+#ifdef TOOLS_ENABLED
+			if (Engine::get_singleton()->is_editor_hint()) {
+				update_configuration_warnings();
+			}
+#endif
 		} break;
 
 		case NOTIFICATION_UNPARENTED: {
@@ -131,6 +136,11 @@ PackedStringArray CollisionShape3D::get_configuration_warnings() const {
 		warnings.push_back(RTR("ConcavePolygonShape3D doesn't support RigidBody3D in another mode than static."));
 	}
 
+	Vector3 scale = get_transform().get_basis().get_scale();
+	if (!(Math::is_zero_approx(scale.x - scale.y) && Math::is_zero_approx(scale.y - scale.z))) {
+		warnings.push_back(RTR("A non-uniformly scaled CollisionShape3D node will probably not function as expected.\nPlease make its scale uniform (i.e. the same on all axes), and change the size of its shape resource instead."));
+	}
+
 	return warnings;
 }
 

scene/3d/physics_body_3d.cpp

@@ -973,12 +973,11 @@ TypedArray<Node3D> RigidBody3D::get_colliding_bodies() const {
 }
 
 PackedStringArray RigidBody3D::get_configuration_warnings() const {
-	Transform3D t = get_transform();
+	PackedStringArray warnings = CollisionObject3D::get_configuration_warnings();
 
-	PackedStringArray warnings = Node::get_configuration_warnings();
-
-	if (ABS(t.basis.get_column(0).length() - 1.0) > 0.05 || ABS(t.basis.get_column(1).length() - 1.0) > 0.05 || ABS(t.basis.get_column(2).length() - 1.0) > 0.05) {
-		warnings.push_back(RTR("Size changes to RigidBody will be overridden by the physics engine when running.\nChange the size in children collision shapes instead."));
+	Vector3 scale = get_transform().get_basis().get_scale();
+	if (ABS(scale.x - 1.0) > 0.05 || ABS(scale.y - 1.0) > 0.05 || ABS(scale.z - 1.0) > 0.05) {
+		warnings.push_back(RTR("Scale changes to RigidBody3D will be overridden by the physics engine when running.\nPlease change the size in children collision shapes instead."));
 	}
 
 	return warnings;

scene/3d/soft_body_3d.cpp

@@ -302,14 +302,6 @@ void SoftBody3D::_notification(int p_what) {
 				_prepare_physics_server();
 			}
 		} break;
-
-#ifdef TOOLS_ENABLED
-		case NOTIFICATION_LOCAL_TRANSFORM_CHANGED: {
-			if (Engine::get_singleton()->is_editor_hint()) {
-				update_configuration_warnings();
-			}
-		} break;
-#endif
 	}
 }
 
@@ -391,11 +383,6 @@ PackedStringArray SoftBody3D::get_configuration_warnings() const {
 		warnings.push_back(RTR("This body will be ignored until you set a mesh."));
 	}
 
-	Transform3D t = get_transform();
-	if ((ABS(t.basis.get_column(0).length() - 1.0) > 0.05 || ABS(t.basis.get_column(1).length() - 1.0) > 0.05 || ABS(t.basis.get_column(2).length() - 1.0) > 0.05)) {
-		warnings.push_back(RTR("Size changes to SoftBody3D will be overridden by the physics engine when running.\nChange the size in children collision shapes instead."));
-	}
-
 	return warnings;
 }