MeshCollider.Create freezes the game

Hi all,

I am struggling with this issue for a while now and i hope that anyone can point me into the right direction here.

I am creating a mesh collider with code.

Code (CSharp):

1. Unity.Physics.MeshCollider.Create(tmpVerts, tmpTriangles);

When this line is run, the game freezes up. For a terrain chunk that is 40x40 vertices in size this takes the game up to 28 seconds to create this mesh collider. I am wondering what i am doing wrong.
tmpVerts and tmpTriangles are simple arrays of int3 and vector3.

I can't figure out why this major freeze is happening. Do anyone of you have an idea? Any advice would be greatly appreciated.

 

Did you try in an empty scene to isolate the problem?
Is it inside a prefab?

 

Here is the exact code i tried this with in a empty scene

Code (CSharp):

1.  void Start()
2.     {
3.         _world = World.DefaultGameObjectInjectionWorld;
4.         terrainColliders = new Dictionary<Vector2Int, BlobAssetReference<Unity.Physics.Collider>>();
5.         _meshGenerator = new MeshGenerator();
6.         BlobAssetStore store = new BlobAssetStore();
7.         _em = _world.EntityManager;
8.         GameObjectConversionSettings settings = GameObjectConversionSettings.FromWorld(_world, store);
9.         Entity e = _em.Instantiate(GameObjectConversionUtility.ConvertGameObjectHierarchy(chunk, settings));
10.         GeneratedMeshData data = _meshGenerator.GenerateTerrainMesh(new Vector2Int(0, 0));
11.  
12.         NativeArray<float3> tmpVerts = new NativeArray<float3>(data.vertices.Length, Allocator.Temp);
13.         for (int i = 0; i < tmpVerts.Length; i++)
14.         {
15.             tmpVerts[i] = data.vertices[i];
16.         }
17.  
18.         NativeArray<int3> tmpTriangles = new NativeArray<int3>(data.triangles.Length, Allocator.Temp);
19.  
20.         for (int i = 0; i < data.triangles.Length / 3; i++)
21.         {
22.             tmpTriangles[i] = new int3(data.triangles[i * 3], data.triangles[i * 3 + 1],
23.                 data.triangles[i * 3 + 2]);
24.         }
25.  
26.         terrainColliders.Add(data.point, BlobAssetReference<Unity.Physics.Collider>.Null);
27.         terrainColliders[data.point] = Unity.Physics.MeshCollider.Create(tmpVerts, tmpTriangles);
28.  
29.         _em.AddComponentData(e, new PhysicsCollider
30.         {
31.             Value = terrainColliders[data.point]
32.         });
33.  
34.         _em.AddComponentData(e, new PhysicsDebugDisplayData
35.         {
36.             DrawColliders = 1,
37.         });
38.     }

I tried an empty scene with only 1 chunk generated. The problem stays the same.

 

Can you try if this freeze happens with Burst disabled?

Your code should be slow (since it's not in a Burst compiled job), bot not this slow I suppose. I'm just wondering if there's a synchronous Burst compilation happening on some of the backend code. For example, our PhysicsShapeAuthoringEditor.cs has a synchronously compiled Burst job to create a mesh for display. That could be causing the freeze.

Then again, if this is instantiated from code, it shouldn't happen. But please try and let me know.

 

I tried it with burst disabled, no change. It still takes the same amount of time to generate the collider. What more can i try?

 

Can you try wrapping this Create() in a BurstCompiled job and see the performance then?

 

Code (CSharp):

1. void Start()
2.     {
3.         _world = World.DefaultGameObjectInjectionWorld;
4.         terrainColliders = new Dictionary<Vector2Int, BlobAssetReference<Unity.Physics.Collider>>();
5.         _meshGenerator = new MeshGenerator();
6.         BlobAssetStore store = new BlobAssetStore();
7.         _em = _world.EntityManager;
8.         GameObjectConversionSettings settings = GameObjectConversionSettings.FromWorld(_world, store);
9.         e = _em.Instantiate(GameObjectConversionUtility.ConvertGameObjectHierarchy(chunk, settings));
10.         GeneratedMeshData data = _meshGenerator.GenerateTerrainMesh(new Vector2Int(0, 0));
11.  
12.         NativeArray<float3> tmpVerts = new NativeArray<float3>(data.vertices.Length, Allocator.Temp);
13.         for (int i = 0; i < tmpVerts.Length; i++)
14.         {
15.             tmpVerts[i] = data.vertices[i];
16.         }
17.  
18.         NativeArray<int3> tmpTriangles = new NativeArray<int3>(data.triangles.Length, Allocator.Temp);
19.  
20.         for (int i = 0; i < data.triangles.Length / 3; i++)
21.         {
22.             tmpTriangles[i] = new int3(data.triangles[i * 3], data.triangles[i * 3 + 1],
23.                 data.triangles[i * 3 + 2]);
24.         }
25.  
26.         terrainColliders.Add(data.point, BlobAssetReference<Unity.Physics.Collider>.Null);
27.        
28.         createJob = new GenerateColliderJob
29.         {
30.             vertices = tmpVerts,
31.             triangles = tmpTriangles,
32.             point = data.point
33.         };
34.  
35.         handle = createJob.Schedule();
36.     }
37.  
38.     // Update is called once per frame
39.     void Update()
40.     {
41.         if (!jobran)
42.         {
43.             handle.Complete();
44.             terrainColliders[createJob.point] = createJob.collider;
45.             _em.AddComponentData(e, new PhysicsCollider
46.             {
47.                 Value = terrainColliders[createJob.point]
48.             });
49.             _em.AddComponentData(e, new PhysicsDebugDisplayData
50.             {
51.                 DrawColliders = 1,
52.             });
53.             jobran = true;
54.         }
55.     }
56. }
57.  
58.  
59. struct GenerateColliderJob : IJobBurstScheduable
60. {
61.     public BlobAssetReference<Unity.Physics.Collider> collider;
62.     public NativeArray<float3> vertices;
63.     public NativeArray<int3> triangles;
64.     public Vector2Int point;
65.    
66.     public void Execute()
67.     {
68.         collider = Unity.Physics.MeshCollider.Create(vertices, triangles);
69.     }
70. }

Quickly coded this, but the result is still the same

 

Is there you could provide vertices and triangles buffer so that I can give this a go locally and check?

 

I think i found the issue ^^ never wait to long to use the debugger haha, was about to copy the values for you when i took notice.

 

So fixed the triangle array size and all works smooth now thanks to you also @petarmHavok

 

My pleasure, glad it was this simple!