Unable To Create Physics Aggregate on Ground Map while using offscreen canvas: Solved

Bugs
1

I seem to have found a weird interaction when using havok with an offscreen canvas.
This following code works properly in both playground and when running on the main thread:

async function testScene(engine) {
  const scene = new BABYLON.Scene(engine);
  const havokInstance = await HavokPhysics({ locateFile: () => 'vendors/HavokPhysics.wasm'});
  const hk = new BABYLON.HavokPlugin(true, havokInstance);
  scene.enablePhysics(new BABYLON.Vector3(0, -9.8, 0), hk);

  const camera = new BABYLON.UniversalCamera("UniversalCamera", new BABYLON.Vector3(0, 0, 0), scene);

  const sphere = BABYLON.MeshBuilder.CreateSphere("sphere", { diameter: 2, segments: 32 }, scene);
  sphere.position.y = 200;

  // Ground
  const ground = BABYLON.MeshBuilder.CreateGroundFromHeightMap("heightmap", '../resources/img.png', {
    width: 1024,
    height: 1024,
    minHeight: 0,
    maxHeight: 256,
    subdivisions: 256
  }, scene);

  //Create Aggregates
  const sphereAggregate = new BABYLON.PhysicsAggregate(sphere, BABYLON.PhysicsShapeType.SPHERE, { mass: 10, restitution: 0.1 }, scene);
  const groundAggregate = new BABYLON.PhysicsAggregate(ground, BABYLON.PhysicsShapeType.MESH, { mass: 0 }, scene);

  return scene;
}

However, when I try running it in a webworker I get “No valid mesh was provided for mesh or convex hull ship parameter. Please provide a mesh with a valid geometry (number of vertices greater than 0).”

If I comment out the line creating the ground aggregate it works fine and I can I see the mesh and sphere. This also indicates that the sphere aggregate is being created properly.

Edit:
Babylon V6.34.1
Chromium v144.0.5735.289

Troubleshooting List:
Updated to Babylon V6.36.1 No Change
Tested a different heightmap image. No Change

Solution:
Delay adding physics aggregate until Mesh has been fully built using onReady per carol’s solution

2

Welcome to the community!

CreateGroundFromHeightMap is not guaranteed to finish building the vertex data on the same frame, so I think that’s what might be causing the “no valid mesh” error. Can you try doing the aggregate creation like this?

// Ground
  const ground = BABYLON.MeshBuilder.CreateGroundFromHeightMap("heightmap", '../resources/img.png', {
    width: 1024,
    height: 1024,
    minHeight: 0,
    maxHeight: 256,
    subdivisions: 256
    onReady: (groundMesh) => {
       const groundAggregate = new BABYLON.PhysicsAggregate(groundMesh, BABYLON.PhysicsShapeType.MESH, { mass: 0 }, scene);
    }
  }, scene);
1 Like
3

Thanks for looking into this Carol.
I think there’s supposed to be a comma after

subdivisions: 256

If not I’m getting unexpected identifier ‘onReady’

After adding a comma I’m getting the same error as before.

PhysicsAggregate._addSizeOptions (physicsAggregate.ts:237:1)
new PhysicsAggregate (physicsAggregate.ts:149:1)

Correction:
I implemented that possible fix into the wrong place. Doing additional testing now as that seems to have been the fix.