/// <summary>
/// Create a View matrix from an existing ProjectionCamera
/// (code acquired with Reflector)
/// </summary>
/// <param name="position">Camera position</param>
/// <param name="lookDirection">Look direction</param>
/// <param name="upDirection">Up direction</param>
/// <returns>View matrix</returns>
public static Matrix3D CreateViewMatrix(Point3D position, Vector3D lookDirection, Vector3D upDirection)
{
Vector3D vectord2 = -lookDirection;
vectord2.Normalize();
Vector3D vectord3 = Vector3D.CrossProduct(upDirection, vectord2);
vectord3.Normalize();
Vector3D vectord4 = Vector3D.CrossProduct(vectord2, vectord3);
Vector3D vectord = (Vector3D)position;
double offsetX = -Vector3D.DotProduct(vectord3, vectord);
double offsetY = -Vector3D.DotProduct(vectord4, vectord);
double offsetZ = -Vector3D.DotProduct(vectord2, vectord);
return(new Matrix3D(
vectord3.X, vectord4.X, vectord2.X, 0,
vectord3.Y, vectord4.Y, vectord2.Y, 0,
vectord3.Z, vectord4.Z, vectord2.Z, 0,
offsetX, offsetY, offsetZ, 1));
}
