public static Matrix4 RotateX(double angle)
{
Matrix4 rotateX = new Matrix4();
rotateX.Type = MatrixType.Rotation;
rotateX.Identity();
double sin = (double)Math.Sin(angle);
double cos = (double)Math.Cos(angle);
rotateX.Matrix[1, 1] = cos;
rotateX.Matrix[1, 2] = sin;
rotateX.Matrix[2, 1] = -sin;
rotateX.Matrix[2, 2] = cos;
return rotateX;
}