Pre-multiply a rotation to this matrix by rotating the given amount of radians about the Z 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>
If <code>M</code> is <code>this</code> matrix and <code>R</code> the rotation matrix,
then the new matrix will be <code>R * M</code>. So when transforming a
vector <code>v</code> with the new matrix by using <code>R * M * v</code>, the
rotation will be applied last!
<p>
In order to set the matrix to a rotation matrix without pre-multiplying the rotation
transformation, use {@link #rotationZ(double) rotationy}.
<p>
Reference: <a href="http://en.wikipedia.org/wiki/Rotation_matrix#Rotation_matrix_from_axis_and_angle">http://en.wikipedia.org</a>
@see #rotationY(double)
@param ang
the angle in radians to rotate about the Z axis
@return this
Pre-multiply a rotation to this matrix by rotating the given amount of radians about the Z 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> If <code>M</code> is <code>this</code> matrix and <code>R</code> the rotation matrix, then the new matrix will be <code>R * M</code>. So when transforming a vector <code>v</code> with the new matrix by using <code>R * M * v</code>, the rotation will be applied last! <p> In order to set the matrix to a rotation matrix without pre-multiplying the rotation transformation, use {@link #rotationZ(double) rotationy}. <p> Reference: <a href="http://en.wikipedia.org/wiki/Rotation_matrix#Rotation_matrix_from_axis_and_angle">http://en.wikipedia.org</a>
@see #rotationY(double)
@param ang the angle in radians to rotate about the Z axis @return this