Mixedrealitytoolkit-unity: Crash when hovering pointer over MeshCollider from asset bundle

[r-o-b-o-t-o]

Describe the bug

Hovering the pointer over an object with a MeshCollider component instantiated from an asset bundle results in an editor crash.

Additional context

I am trying to use the OnPointerClicked event from the PointerHandler component on an object that has a MeshCollider and a NearInteractionTouchable component, instantiated from an asset bundle. This works as expected if the same object is dragged into the scene or instantiated from a prefab.

Log errors

Click to display logs

Assertion failed on expression: 'chanType.dimension == 0'
UnityEngine.RaycastHit:CalculateRaycastTexCoord_Injected(Collider, Vector2&, Vector3&, UInt32, Int32, Vector2&)
UnityEngine.RaycastHit:CalculateRaycastTexCoord(Collider, Vector2, Vector3, UInt32, Int32)
UnityEngine.RaycastHit:get_textureCoord()
Microsoft.MixedReality.Toolkit.Input.MixedRealityRaycastHit:.ctor(Boolean, RaycastHit) (at Assets\MixedRealityToolkit\Definitions\InputSystem\MixedRealityRaycastHit.cs:36)
Microsoft.MixedReality.Toolkit.Input.DefaultRaycastProvider:Raycast(RayStep, LayerMask[], Boolean, MixedRealityRaycastHit&) (at Assets\MixedRealityToolkit.Services\InputSystem\DefaultRaycastProvider.cs:43)
Microsoft.MixedReality.Toolkit.Input.FocusProvider:QueryScene(IMixedRealityPointer, IMixedRealityRaycastProvider, LayerMask[], PointerHitResult, Int32, Boolean) (at Assets\MixedRealityToolkit.Services\InputSystem\FocusProvider.cs:1140)
Microsoft.MixedReality.Toolkit.Input.FocusProvider:UpdatePointer(PointerData) (at Assets\MixedRealityToolkit.Services\InputSystem\FocusProvider.cs:971)
Microsoft.MixedReality.Toolkit.Input.FocusProvider:UpdatePointers() (at Assets\MixedRealityToolkit.Services\InputSystem\FocusProvider.cs:897)
Microsoft.MixedReality.Toolkit.Input.FocusProvider:Update() (at Assets\MixedRealityToolkit.Services\InputSystem\FocusProvider.cs:540)
Microsoft.MixedReality.Toolkit.<>c:<UpdateAllServices>b__63_0(IMixedRealityService) (at Assets\MixedRealityToolkit\Services\MixedRealityToolkit.cs:941)
Microsoft.MixedReality.Toolkit.MixedRealityToolkit:ExecuteOnAllServicesInOrder(Action`1) (at Assets\MixedRealityToolkit\Services\MixedRealityToolkit.cs:1019)
Microsoft.MixedReality.Toolkit.MixedRealityToolkit:UpdateAllServices() (at Assets\MixedRealityToolkit\Services\MixedRealityToolkit.cs:941)
Microsoft.MixedReality.Toolkit.MixedRealityToolkit:Update() (at Assets\MixedRealityToolkit\Services\MixedRealityToolkit.cs:629)

[C:\buildslave\unity\build\Runtime/Graphics/Mesh/Mesh.h line 140] 
(Filename: Assets/MixedRealityToolkit/Definitions/InputSystem/MixedRealityRaycastHit.cs Line: 36)

Stacktrace:

  at <unknown> <0xffffffff>
  at (wrapper managed-to-native) UnityEngine.RaycastHit.CalculateRaycastTexCoord_Injected (UnityEngine.Collider,UnityEngine.Vector2&,UnityEngine.Vector3&,uint,int,UnityEngine.Vector2&) [0x0000e] in <18b38ade9b8549a5aff4b379f33eccec>:0
  at UnityEngine.RaycastHit.CalculateRaycastTexCoord (UnityEngine.Collider,UnityEngine.Vector2,UnityEngine.Vector3,uint,int) [0x0000a] in <18b38ade9b8549a5aff4b379f33eccec>:0
  at UnityEngine.RaycastHit.get_textureCoord () [0x0001a] in <18b38ade9b8549a5aff4b379f33eccec>:0
  at Microsoft.MixedReality.Toolkit.Input.MixedRealityRaycastHit..ctor (bool,UnityEngine.RaycastHit) [0x00052] in D:\Projets\Unity\TestMRTK\Assets\MixedRealityToolkit\Definitions\InputSystem\MixedRealityRaycastHit.cs:36
  at Microsoft.MixedReality.Toolkit.Input.DefaultRaycastProvider.Raycast (Microsoft.MixedReality.Toolkit.Physics.RayStep,UnityEngine.LayerMask[],bool,Microsoft.MixedReality.Toolkit.Input.MixedRealityRaycastHit&) [0x00013] in D:\Projets\Unity\TestMRTK\Assets\MixedRealityToolkit.Services\InputSystem\DefaultRaycastProvider.cs:43
  at Microsoft.MixedReality.Toolkit.Input.FocusProvider.QueryScene (Microsoft.MixedReality.Toolkit.Input.IMixedRealityPointer,Microsoft.MixedReality.Toolkit.Input.IMixedRealityRaycastProvider,UnityEngine.LayerMask[],Microsoft.MixedReality.Toolkit.Input.FocusProvider/PointerHitResult,int,bool) [0x00090] in D:\Projets\Unity\TestMRTK\Assets\MixedRealityToolkit.Services\InputSystem\FocusProvider.cs:1140
  at Microsoft.MixedReality.Toolkit.Input.FocusProvider.UpdatePointer (Microsoft.MixedReality.Toolkit.Input.FocusProvider/PointerData) [0x000dd] in D:\Projets\Unity\TestMRTK\Assets\MixedRealityToolkit.Services\InputSystem\FocusProvider.cs:971
  at Microsoft.MixedReality.Toolkit.Input.FocusProvider.UpdatePointers () [0x00085] in D:\Projets\Unity\TestMRTK\Assets\MixedRealityToolkit.Services\InputSystem\FocusProvider.cs:897
  at Microsoft.MixedReality.Toolkit.Input.FocusProvider.Update () [0x00011] in D:\Projets\Unity\TestMRTK\Assets\MixedRealityToolkit.Services\InputSystem\FocusProvider.cs:540
  at Microsoft.MixedReality.Toolkit.MixedRealityToolkit/<>c.<UpdateAllServices>b__63_0 (Microsoft.MixedReality.Toolkit.IMixedRealityService) [0x00000] in D:\Projets\Unity\TestMRTK\Assets\MixedRealityToolkit\Services\MixedRealityToolkit.cs:941
  at Microsoft.MixedReality.Toolkit.MixedRealityToolkit.ExecuteOnAllServicesInOrder (System.Action`1<Microsoft.MixedReality.Toolkit.IMixedRealityService>) [0x00026] in D:\Projets\Unity\TestMRTK\Assets\MixedRealityToolkit\Services\MixedRealityToolkit.cs:1019
  at Microsoft.MixedReality.Toolkit.MixedRealityToolkit.UpdateAllServices () [0x00001] in D:\Projets\Unity\TestMRTK\Assets\MixedRealityToolkit\Services\MixedRealityToolkit.cs:941
  at Microsoft.MixedReality.Toolkit.MixedRealityToolkit.Update () [0x0000c] in D:\Projets\Unity\TestMRTK\Assets\MixedRealityToolkit\Services\MixedRealityToolkit.cs:629
  at (wrapper runtime-invoke) object.runtime_invoke_void__this__ (object,intptr,intptr,intptr) [0x00020] in <437ba245d8404784b9fbab9b439ac908>:0

=================================================================
Got a SIGSEGV while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries 
used by your application.
=================================================================

Complete logs:
Editor.log

To reproduce

1. Download the project
   TestMRTK.zip

2. Open the Main scene from the Scenes folder.

3. Enter play mode.
4. Press the spacebar to display the hand, hover over the astronaut on the right.

Expected behavior

Hovering the pointer over an object with a MeshCollider instantiated from an asset bundle should not cause a crash.

Screenshots

Demo gif:

Setup

• Unity 2019.3.5f1
• MRTK 2.3.0

Target platform

• HoloLens 2 (UWP ARM64)

[keveleigh]

@Cameron-Micka Does this seem related to anything you've seen? Related at all to the 2019.3 mesh issues you reported?

[wiwei]

This looks like this issue:

https://issuetracker.unity3d.com/issues/editor-crashes-when-access-to-raycasthit-dot-texturecoord2-collider-is-meshcollider-and-mesh-dot-isreadable-equals-false

[Cameron-Micka]

@Cameron-Micka Does this seem related to anything you've seen? Related at all to the 2019.3 mesh issues you reported?

The issue I was seeing was in a ARM player build only. So probably not related?

[wiwei]

Though looking at the Unity docs here it also looks like this is expected:

https://docs.unity3d.com/ScriptReference/Mesh-isReadable.html

[r-o-b-o-t-o]

Though looking at the Unity docs here it also looks like this is expected:

https://docs.unity3d.com/ScriptReference/Mesh-isReadable.html

Checking Read/Write Enabled on the mesh asset and rebuilding the asset bundle does indeed fix the issue. Didn't think this would be completely Unity's fault, sorry for the inconvenience! And thank you for the help 😀

[keveleigh]

I wonder if it's worth us adding a guard around this, if the collider is a MeshCollider we check isReadable before accessing?

[keveleigh]

Something like

c# MeshCollider meshCollider = hitInfo.collider as MeshCollider; if (meshCollider == null || meshCollider.sharedMesh.isReadable) { textureCoord2 = hitInfo.textureCoord2; } else { textureCoord2 = Vector2.zero; }

[Cameron-Micka]

I think that's a good temporary fix until Unity introduces a fix.