fix: PhysicsComponent created with GetOrCreate<T> is unusable (#2422)

* Run proper Rigidbody setup when adding ColliderShape

* Added test case for proper setup with GetOrCreate

* Followed similar Bepu format with creation of ReAttach method

* Reformatted files edited

* Revert "Reformatted files edited"

This reverts commit 1c9b03e.

Author: dloe

sources/engine/Stride.Physics.Tests/ColliderShapesTest.cs

@@ -37,7 +37,7 @@ public static bool ScreenPositionToWorldPositionRaycast(Vector2 screenPos, Camer
                 if (hitResult.Succeeded)
                 {
                     return true;
-                }                
+                }
             }
 
             return false;
@@ -243,6 +243,51 @@ public void ColliderShapesTest1()
                 Assert.Equal(0.0f, (new Vector3(-2.861034E-06f, 3.889218E-06f, -1f) - hit.Normal).Length(), 3f);
                 Assert.Equal(0.0f, (new Vector3(-5.366335f, -0.08297831f, -17.9267f) - hit.Point).Length(), 3f);
 
+                game.Exit();
+            });
+            RunGameTest(game);
+        }
+
+        /// <summary>
+        /// Verify PhysicsComponent creation through the use of GetOrCreate<T>
+        /// If component is added this way, must ensure ColliderShape is properly setup if added later
+        /// </summary>
+        [Fact]
+        public void VerifyColliderShapeSetup()
+        {
+            var game = new ColliderShapesTest();
+            game.Script.AddTask(async () =>
+            {
+                game.ScreenShotAutomationEnabled = false;
+                await game.Script.NextFrame();
+                await game.Script.NextFrame();
+
+                var simulation = game.SceneSystem.SceneInstance.RootScene.Entities.First(ent => ent.Name == "Simulation").Get<StaticColliderComponent>().Simulation;
+                var cube = game.SceneSystem.SceneInstance.RootScene.Entities.First(ent => ent.Name == "CubePrefab1");
+                
+                var body = cube.GetOrCreate<RigidbodyComponent>();
+
+                //verify values not properly set up
+                Assert.Null(body.ColliderShape);
+                Assert.Equal(RigidBodyTypes.Static, body.RigidBodyType);
+                Assert.False(body.OverrideGravity);
+
+                //for further debug, can set breakpoint and check body.Simulation.discreteDynamicWorld.CollisionObjectArray before and after
+                //the collider shape is attached to see it properly added
+
+                //add collider shape
+                body.ColliderShape = new SphereColliderShape(false, 1.0f);
+                //check if proper colliderShape setup took place
+                Assert.True(body.ColliderShape != null);
+                Assert.Equal(ColliderShapeTypes.Sphere, body.ColliderShape.Type);
+                Assert.Equal(RigidBodyTypes.Dynamic, body.RigidBodyType);
+
+                body.OverrideGravity = true;
+                //to verify InternalRigidBody was properly set up we can change properties such as Mass or OverrideGravity 
+                //that normally would return void if there are no InternalRigidBody values
+                Assert.True(body.OverrideGravity);
+
+
                 game.Exit();
             });
             RunGameTest(game);

sources/engine/Stride.Physics/Elements/RigidbodyComponent.cs

@@ -85,7 +85,11 @@ public float Mass
 
                 mass = value;
 
-                if (InternalRigidBody == null) return;
+                if (InternalRigidBody == null)
+                {
+                    return;
+                }
+                    
 
                 var inertia = ColliderShape.InternalShape.CalculateLocalInertia(value);
                 InternalRigidBody.SetMassProps(value, inertia);
@@ -114,7 +118,11 @@ public override ColliderShape ColliderShape
                     return;
 
                 if (InternalRigidBody == null)
+                {
+                    //When setting ColliderShape, setup could have been previously skipped (eg when PhysicsComponent is created using GetOrCreate)
+                    ReAttach();
                     return;
+                }
 
                 if (NativeCollisionObject != null)
                     NativeCollisionObject.CollisionShape = value.InternalShape;
@@ -193,7 +201,11 @@ public bool OverrideGravity
             {
                 overrideGravity = value;
 
-                if (InternalRigidBody == null) return;
+                if (InternalRigidBody == null)
+                {
+                    return;
+                }
+                    
 
                 if (value)
                 {
@@ -341,6 +353,7 @@ protected override void OnAttach()
 
         protected override void OnDetach()
         {
+
             MotionState.Dispose();
             MotionState.Clear();
 

sources/engine/Stride.Physics/Engine/PhysicsComponent.cs

@@ -681,6 +681,32 @@ internal void Attach(PhysicsProcessor.AssociatedData data)
             }
         }
 
+        /// <summary>
+        /// Ran when properties of Components may not be fully setup and need to be reintegrated (eg GetOrCreate<RigidbodyComponent> and adding collidershapes)
+        /// </summary>
+        internal void ReAttach()
+        {
+            //TODO: Could consider fully detaching and then rebuilding, but ideally this would cause null refs on Rigidbody OnDetach calls
+            //Shouldnt call detach, because at this point the user has added new components and this runs as a check to rebuild as needed.
+            //Entire wipes to rebuild causes loss in the data that the user has just added (and is slower)
+
+            Entity.Transform.UpdateWorldMatrix();
+
+            BoneIndex = -1;
+
+            OnAttach();
+
+            //ensure ignore collisions
+            if (ignoreCollisionBuffer != null && NativeCollisionObject != null)
+            {
+                foreach (var kvp in ignoreCollisionBuffer)
+                {
+                    IgnoreCollisionWith(kvp.Key, kvp.Value);
+                }
+                ignoreCollisionBuffer = null;
+            }
+        }
+
         internal void Detach()
         {
             Data = null;