ply format ascii 1.0 comment VCGLIB generated element vertex 6 property float x property float y property float z element face 3 property list uchar int vertex_indices end_header -0.5 3 0 0.5 3 0 -1 4 0 0 4 0 1 4 0 0 6 0 3 0 3 2 3 1 4 3 3 2 4 5