Vertex error and no colors on thin instances after upgrade

Bugs
12

Yes, that’s what I’ve been looking at as well, although I don’t fully grasp what’s happening there. My material is a PBRMetallicRoughnessMaterial.

Here are some of the (simplified) manipulations on the material and instances I’m running in case it helps:

export const makeMaterial = ({
  scene,
  name,
  materialParameters: {
    baseColor,
    metallicRatio = 0,
    roughnessRatio = 1,
    alphaRatio = 1
  },
  onError = () => {}
}) => {
  const material = new PBRMetallicRoughnessMaterial(name, scene)
  material.baseColor = Color3.FromHexString(baseColor)
  material.metallic = metallicRatio
  material.roughness = roughnessRatio
  material.alpha = alphaRatio
  material.onError = onError
  return material
}

export const instantiateMesh = ({
  mesh,
  instances,
  scalingFn,
  colorFn
}) => {
  // prepare root mesh for instancing
  mesh.alwaysSelectAsActiveMesh = true
  if (mesh.isPickable === true) {
    mesh.thinInstanceEnablePicking = true
  }
  // prepare custom buffer for instances color
  // https://doc.babylonjs.com/divingDeeper/mesh/copies/instances#custom-buffers
  let bufferColors = new Float32Array(4 * instances.length)
  // create thin instances
  let bufferMatrices = new Float32Array(16 * instances.length)
  let index = 0
  const addInstanceToBuffers = ({
    instance,
    __instanceIndex
  }) => {
    // position mesh
    const { position, rotation, scaling } = computeMeshPosition({
      instance,
      useQuaternion: true
    })
    const instanceSpecificScaling = scaling.scale(scalingFn(instance))
    const matrix = Matrix.Compose(instanceSpecificScaling, rotation, position)
    matrix.copyToArray(bufferMatrices, index * 16)
    // instance base color in RGBA (with multi-materials suport)
    const color = Color3.FromHexString(colorFn(instance))
    bufferColors[index * 4 + 0] = color.r
    bufferColors[index * 4 + 1] = color.g
    bufferColors[index * 4 + 2] = color.b
    bufferColors[index * 4 + 3] = 1 // we don't support alpha on instance due to render order issues, see babylon forum
    // next
    index++
  }
  instances.forEach((instance, __instanceIndex) =>
    addInstanceToBuffers({ instance, __instanceIndex })
  )
  const staticMatrices = false
  const staticColors = false
  mesh.thinInstanceSetBuffer('matrix', bufferMatrices, 16, staticMatrices)
  mesh.thinInstanceSetBuffer('color', bufferColors, 4, staticColors)
}

I had thought maybe I needed to name the buffer “instanceColor” instead of “color” (looking at the changes in the commit) but it’s doesn’t solve the issue and the PG still works with “color”. Is it sure the shader is reading from the “color” buffer?

I’m still trying to isolate a repro.