vertexAttribPointer method 
    
      
void
vertexAttribPointer(
 - int index, 
- int size, 
- int type, 
- bool normalized, 
- int stride, 
- int offset, 
) 
    
    
  Implementation
  void vertexAttribPointer(int index, int size, int type, bool normalized, int stride, int offset) {
  startCheck('vertexAttribPointer');
  Pointer<Void> offsetPointer = Pointer<Void>.fromAddress(offset);
  using((Arena arena) {
    gl.glVertexAttribPointer(index, size, type, normalized ? 1 : 0, stride, offsetPointer);
  });
  checkError('vertexAttribPointer');
  //calloc.free(offsetPointer);
}