rotateZ method
angle - the angle to rotate in radians.
Rotates the object around z axis in local space.
Implementation
Object3D rotateZ(double angle) {
  return rotateOnAxis(_zAxis, angle);
}angle - the angle to rotate in radians.
Rotates the object around z axis in local space.
Object3D rotateZ(double angle) {
  return rotateOnAxis(_zAxis, angle);
}