I am working with MeshAnchors, and I am having troubles getting to the classification of the triangles/faces.
This post references the MeshAnchor.Geometry, and that struct does have a property named "classifications", but it is of type GeometrySource. I cannot find any classification information in GeometrySource. Am I missing something there?
I think I am looking for something of type MeshAnchor.MeshClassification, but I cannot find any structs with this as a property.
You are on the right track. Here are two extensions which should get you the mesh classification of a single face in the mesh (I haven't tested it!):
extension GeometrySource {
subscript(_ index: Int32) -> CUnsignedChar {
precondition(format == .uchar, "This subscript operator can only be used on GeometrySource instances with format .uchar")
return buffer.contents().advanced(by: offset + (stride * Int(index))).assumingMemoryBound(to: CUnsignedChar.self).pointee
}
}
extension MeshAnchor {
public func classificationOf(face index: Int32) -> MeshAnchor.MeshClassification? {
guard let classifications = self.geometry.classifications else { return nil }
let classification = classifications[index]
return MeshAnchor.MeshClassification(rawValue: Int(classification)) ?? nil
}
}
Thanks! I took a slightly less efficient approach (mainly, so I could understand all the nested data structures), and I could get the results I wanted. For example, I applied occlusion material to .seat (which includes couches) or .floor), so I could get my couch/chairs or floor to appear through the virtual content in mixed reality mode.
I made some progress.
When creating the SceneReconstructionProvider, specify the classifications mode.
let sceneReconstruction = SceneReconstructionProvider(modes: [.classification])
Then the MeshAnchor.Geometry's classification property is set, and here are some example values
count: 11342
description: GeometrySource(count: 11342, format: MTLVertexFormat(rawValue: 45))
format: 45
componentsPerVector: 1
offset: 0
stride: 1
So I am guessing the buffer contains a sequence values that map to the MeshAnchor.MeshClassification raw values. (Now I just need to figure out which MTLVertexFormat case has a raw value of 45 :-)
Edit: uchar is type 45. So, the buffer contains a sequence of unsigned bytes.
You are on the right track. Here are two extensions which should get you the mesh classification of a single face in the mesh (I haven't tested it!):
extension GeometrySource {
subscript(_ index: Int32) -> CUnsignedChar {
precondition(format == .uchar, "This subscript operator can only be used on GeometrySource instances with format .uchar")
return buffer.contents().advanced(by: offset + (stride * Int(index))).assumingMemoryBound(to: CUnsignedChar.self).pointee
}
}
extension MeshAnchor {
public func classificationOf(face index: Int32) -> MeshAnchor.MeshClassification? {
guard let classifications = self.geometry.classifications else { return nil }
let classification = classifications[index]
return MeshAnchor.MeshClassification(rawValue: Int(classification)) ?? nil
}
}
Thanks! I took a slightly less efficient approach (mainly, so I could understand all the nested data structures), and I could get the results I wanted. For example, I applied occlusion material to .seat (which includes couches) or .floor), so I could get my couch/chairs or floor to appear through the virtual content in mixed reality mode.