Resolved ObjectDisposedException: Cannot access a disposed object. When using PhysicsWorld.CastRay().

Hi all,

Can someone point out the issue with my code here please. I'm getting this error when I try to perform a raycast from the mouse screen position:

Code (CSharp):

1. ObjectDisposedException: Cannot access a disposed object.
2. Object name: 'The NativeArray has been disposed, it is not allowed to access it'.

I have a PlayerInputSystem that is used to provide input data to entities that need it.
In

OnCreate()

I get the physics world:

Code (CSharp):

1. physicsWorld = World.GetOrCreateSystem<BuildPhysicsWorld>().PhysicsWorld;

In

OnUpdate()

I'm doing this:

Code (CSharp):

1. Vector2 mousePosition = playerActions.MousePosition.ReadValue<Vector2>();
2. float3 raycastHitPoint = RaycastMousePosition(mousePosition);

I also get some other inputs, and then I have an Entities.ForEach() and update my input data component to pass this data to the entities.

And here is the RaycastMousePosition method:

Code (CSharp):

1.     private float3 RaycastMousePosition(Vector2 mousePosition)
2.     {
3.         UnityEngine.Ray mouseRay = Camera.main.ScreenPointToRay(mousePosition);
4.         RaycastInput mouseRaycast = new RaycastInput
5.         {
6.             Start = mouseRay.origin,
7.             End = mouseRay.GetPoint(RAYCAST_DISTANCE),
8.             Filter = CollisionFilter.Default
9.         };
10.  
11.         if (physicsWorld.CastRay(mouseRaycast, out Unity.Physics.RaycastHit raycastHit))
12.         {
13.             return raycastHit.Position;
14.         }
15.  
16.         return float3.zero;
17.     }

The error is not very descriptive, but I can comment out the raycast and the error disappears. It seems that my physicsWorld is disposed at this point. Is there something I am missing?

 

Unity version: 2020.3.19f1
Unity Physics version: 0.6.0-preview.3
Entities version: 0.17.0-preview.42

 

Have you got the physics dependency handle?

 

I haven't specifically applied any dependencies. I didn't think you had to add manual dependencies when extending

SystemBase 

and adding code in OnUpdate(). I wondered whether it is to do with incorrect UpdateInGroup/After/Before attributes. Here is the full system:

Code (CSharp):

1. using Unity.Entities;
2. using UnityEngine;
3. using Unity.Physics;
4. using Unity.Physics.Systems;
5. using Unity.Mathematics;
6.  
7. [UpdateInGroup(typeof(FixedStepSimulationSystemGroup))]
8. [UpdateAfter(typeof(ExportPhysicsWorld))]
9. [UpdateBefore(typeof(EndFramePhysicsSystem))]
10. public class PlayerInputSystem : SystemBase
11. {
12.     private Input input;
13.     private Input.PlayerActions playerActions;
14.     private PhysicsWorld physicsWorld;
15.  
16.     private float RAYCAST_DISTANCE = 100;
17.  
18.     protected override void OnCreate()
19.     {
20.         input = new Input();
21.         input.Enable();
22.         playerActions = input.Player;
23.         physicsWorld = World.GetOrCreateSystem<BuildPhysicsWorld>().PhysicsWorld;
24.     }
25.  
26.     protected override void OnUpdate()
27.     {
28.         float horizontal = playerActions.Horizontal.ReadValue<float>();
29.         float vertical = playerActions.Vertical.ReadValue<float>();
30.         Vector2 mouseDelta = playerActions.MouseDelta.ReadValue<Vector2>();
31.         Vector2 mousePosition = playerActions.MousePosition.ReadValue<Vector2>();
32.  
33.         // playerActions.Action.triggered is broken!
34.         // Use playerActions.Action.ReadValue<float>() != 0 ? true : false; for bools instead
35.         bool jump = playerActions.Jump.ReadValue<float>() != 0 ? true : false;
36.         bool orient = playerActions.Orient.ReadValue<float>() != 0 ? true : false;
37.         bool mouseLook = playerActions.MouseLook.ReadValue<float>() != 0 ? true : false;
38.  
39.         float3 raycastHitPoint = RaycastMousePosition(mousePosition);
40.  
41.         Entities
42.             .ForEach(
43.             (ref PlayerInputData inputData) =>
44.             {
45.                 inputData.horizontal = horizontal;
46.                 inputData.vertical = vertical;
47.                 inputData.jump = jump;
48.                 inputData.orient = orient;
49.                 inputData.mouseLook = mouseLook;
50.                 inputData.mouseDelta = mouseDelta;
51.                 inputData.mouseRayHitPoint = raycastHitPoint;
52.             }).Schedule();
53.     }
54.  
55.     private float3 RaycastMousePosition(Vector2 mousePosition)
56.     {
57.         UnityEngine.Ray mouseRay = Camera.main.ScreenPointToRay(mousePosition);
58.         RaycastInput mouseRaycast = new RaycastInput
59.         {
60.             Start = mouseRay.origin,
61.             End = mouseRay.GetPoint(RAYCAST_DISTANCE),
62.             Filter = CollisionFilter.Default
63.         };
64.  
65.         if (physicsWorld.CastRay(mouseRaycast, out Unity.Physics.RaycastHit raycastHit))
66.         {
67.             return raycastHit.Position;
68.         }
69.  
70.         return float3.zero;
71.     }
72. }
73.  

 

I have manged to solve the issue. The problem is that I was taking a reference to the PhysicsWorld in OnCreate(), but I need to get a new PhysicsWorld each time I need to cast.

Here are the changes:

Code (CSharp):

1.     private BuildPhysicsWorld buildPhysicsWorld;
2.  
3.     // ... etc.
4.  
5.     protected override void OnCreate()
6.     {
7.         buildPhysicsWorld = World.GetOrCreateSystem<BuildPhysicsWorld>();
8.  
9.         // ... etc.
10.     }
11.  

And the changes in my

RaycastMousePosition()

method:

Code (CSharp):

1. private float3 RaycastMousePosition(Vector2 mousePosition)
2.     {
3.         CollisionWorld collisionWorld = buildPhysicsWorld.PhysicsWorld.CollisionWorld;
4.  
5.         // ... etc.
6.  
7.         if (collisionWorld.CastRay(mouseRaycast, out Unity.Physics.RaycastHit raycastHit))
8.         {
9.             return raycastHit.Position;
10.         }
11.  
12.         return float3.zero;
13.     }

I also made some other changes that were unrelated to the error. I switched to CollisionWorld, removed unnecessary attributes and added the [AlwaysUpdateSystem] attribute.