/// <summary>
/// Rotates current coordinate system.
/// </summary>
/// <param name="angle">Is specified in radians.</param>
public static void Rotate(this Nvg nvg, float angle)
{
Matrix3X2 <float> t = nvg.TransformRotate(angle);
nvg.stateStack.CurrentState.Transform = nvg.TransformPremultiply(nvg.stateStack.CurrentState.Transform, t);
}