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.

1 files changed, 18 insertions, 0 deletions

diff --git a/scene/3d/collision_object_3d.cpp b/scene/3d/collision_object_3d.cpp
index a98be62dfa..4fc88728aa 100644
--- a/scene/3d/collision_object_3d.cpp
+++ b/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;
 }