Assemble an indexed BufferGeometry from flat position, normal and
uv arrays plus a triangle index list. The index buffer is automatically
Uint16Array or Uint32Array depending on the vertex count, and bounding
volumes are computed. Optional draw groups ([start, count, materialIndex])
may be supplied for multi-material meshes.
Assemble an indexed BufferGeometry from flat
position,normalanduvarrays plus a triangle index list. The index buffer is automaticallyUint16ArrayorUint32Arraydepending on the vertex count, and bounding volumes are computed. Optional drawgroups([start, count, materialIndex]) may be supplied for multi-material meshes.