//public static Matrix3 ExtractMatrix3(this Matrix4 mat4)
//{
// Matrix3 mat3d = new Matrix3();
// for (int i = 0; i < 3; i++)
// {
// for (int j = 0; j < 3; j++)
// mat3d[i, j] = mat4[i, j];
// }
// return mat3d;
//}
public static Matrix4 PutTheMatrix4together(this Matrix4 mat4d, Vector3 T, Matrix3 Rotation)
{
//put the 4d matrix together
Matrix3 r3D = Rotation.Clone();
Matrix4 myMatrix = new Matrix4();
myMatrix = myMatrix.FromMatrix3(r3D);
myMatrix[0, 3] = T.X;
myMatrix[1, 3] = T.Y;
myMatrix[2, 3] = T.Z;
myMatrix[3, 3] = 1f;
return(myMatrix);
}