rotateX method
Rotate the geometry about the X axis. This is typically done as a one time
operation, and not during a loop. Use rotation for typical
real-time mesh rotation.
Implementation
BufferGeometry rotateX(double angle) {
  // rotate geometry around world x-axis
  _bufferGeometrym1.makeRotationX(angle);
  applyMatrix4(_bufferGeometrym1);
  return this;
}