FilterByPosition.swift

extension Mesh {
  func insideProjectedPosition(in arView: ARView) -> Self {
    guard !vertices.isEmpty, !faces.isEmpty else { return self }

    var filteredFaces: [Mesh.Face] = []
    var filteredVertices: [SIMD3<Float>] = []

    for face in faces {
      var verticesInsideBounds: [SIMD3<Float>] = []

      for vertexIndex in face.triangle {
        let vertex = vertices[vertexIndex]
        if let vertexPosition = arView.project(vertex) {
          if arView.bounds
            .inset(by: .init(top: 100, left: 100, bottom: 100, right: 100))
            .contains(vertexPosition)
          {
            verticesInsideBounds.append(vertex)
          }
        }
      }

      if verticesInsideBounds.count == 3 {
        filteredFaces.append(face)
        filteredVertices.append(contentsOf: verticesInsideBounds)
      }
    }

    return Mesh(
      vertices: filteredVertices,
      faces: filteredFaces
    )
  }
}