Multiplies the current matrix by one that rotates the around the axis-vector specified by x, y and z
            .
The rotation follows the right-hand thumb rule so for example rotating by 10 degrees about the axis-vector (0, 0, 1) causes a small counter-clockwise rotation.
| this | |
| angle | Angle in degrees to rotate. | 
| x | X-component of vertex to rotate around. | 
| y | Y-component of vertex to rotate around. | 
| z | Z-component of vertex to rotate around. |