Resolved Unity Physics runtime mesh collider creation and modification

Unity Entities Graphics has some great convenience features to enable runtime mesh creation / modification:

1. RenderMeshUtility.AddComponents for runtime mesh creation
2. MaterialMeshInfo (and RegisterMesh / RegisterMaterial calls) for efficiently changing meshes at runtime

Are there any plans to add similar helpers and concepts for DOTS Physics?

Procedural terrain is a good use case. There is the need to create meshes at runtime and, if the terrain is modifiable at runtime, then there is a need to efficiently update mesh colliders at runtime.

I've rolled my own "PhysicsUtility.AddComponents"-style helpers for creating a mesh collider at runtime by looking at the physics internals, but this is obviously quite fragile. Specifically, taking a Mesh (or MeshDataArray), ColliderFilter and (physics) Material and building a BlobAssetReference<Collider>. It sure would be nice to have a supported helper API to rely on for this. I have no idea if it's possible to change a collider efficiently at runtime without building a whole new collider, but I'd love if there was a way to build the collider asynchronously and do a MaterialMeshInfo-style ID swap efficiently.

 

Yes, that's correct.

My own implementation uses Physics.MeshCollider.Create() under the hood, and it pretty much does what you describe... it gets the MeshData and builds the vertices and triangles NativeArrays in a job and passes it to Physics.MeshCollider.Create() in another job.

It's not that any of that is particularly difficult, but there are some fiddly bits dealing with the correct index format of the MeshData to build the triangles, handle all the sub-meshes, wrap it in jobs, etc. I definitely had to go dig into the physics codebase to figure out exactly what to do. It just seems like there should be something in the general public API that takes a Mesh, MeshData or MeshDataArray (along with the CollisionFilter and Material) and spits out a BlobAssetReference<Collider> and just abstracts away the internal complexity of these fairly common operations.

My wishlist would be to add:

Code (CSharp):

1.  
2. public static BlobAssetReference<Collider> Create( Mesh mesh, CollisionFilter filter, Material material );
3. public static BlobAssetReference<Collider> Create( MeshData meshData, CollisionFilter filter, Material material );
4. public static BlobAssetReference<Collider> Create( MeshDataArray meshDataArray, CollisionFilter filter, Material material );
5.  

... maybe along with some simple jobs to wrap the three burst-able calls (NativeArrays, MeshData and MeshDataArray). Again, something that is trivial to write, but is just another thing that many people will have to do.

Finally, in my PhysicsUtility class, I have it all wrapped in a call that has RenderMeshUtility.AddComponents() vibes, taking an Entity and EntityManager and adding the correct components. But, that's just gravy.