/**
  * Calculates the model matrix for this {@link ATransformable3D} object.
  *
  * @param parentMatrix {@link Matrix4} The parent matrix, if any, to apply to this object.
  */
 public void calculateModelMatrix(final Matrix4 parentMatrix) {
   mMMatrix.setAll(mPosition, mScale, mOrientation);
   if (parentMatrix != null) {
     mMMatrix.leftMultiply(parentMatrix);
   }
 }