Set this matrix to a rotation transformation about the X axis.
<p>
When used with a right-handed coordinate system, the produced rotation will rotate a vector
counter-clockwise around the rotation axis, when viewing along the negative axis direction towards the origin.
When used with a left-handed coordinate system, the rotation is clockwise.
<p>
Reference: <a href="http://en.wikipedia.org/wiki/Rotation_matrix#Basic_rotations">http://en.wikipedia.org</a>
Set this matrix to a rotation transformation about the X axis. <p> When used with a right-handed coordinate system, the produced rotation will rotate a vector counter-clockwise around the rotation axis, when viewing along the negative axis direction towards the origin. When used with a left-handed coordinate system, the rotation is clockwise. <p> Reference: <a href="http://en.wikipedia.org/wiki/Rotation_matrix#Basic_rotations">http://en.wikipedia.org</a>
@param ang the angle in radians @return this