code: public void setRotation(float r) {
  		double d = 2.0 * Math.PI;
  		rotationRadians = (float) ((r + initialRotation) % d);
  		if (rotationRadians < 0) {
  			rotationRadians += d;
  		}
  		float[] matrix = matrix();
  		scaledWidth = matrix[DX] - matrix[CX];
  		scaledHeight = matrix[DY] - matrix[CY];
  	}
docs: Sets the rotation of the image in radians.
  
  @param r
  rotation in radians