lookto

Matrix VFunction Matrix::LookTo(const Vector& position, const Vector& direction, const Vector& up)
{
    Vector vForward = direction;
    Vector vRight = Vector::Normalize3(Vector::Cross(up, vForward));
    Vector vUp = Vector::Cross(vForward, vRight);

    Vector vNegativePosition = _mm_mul_ps(position, Vector::Constant::NegativeOne);
    Vector vX = Vector::Dot3(vForward, vNegativePosition);
    Vector vY = Vector::Dot3(vRight, vNegativePosition);
    Vector vZ = Vector::Dot3(vUp, vNegativePosition);

    Matrix vResult;
    vResult.z = Vector::Select(vX, vForward, Vector::Constant::Select1110);
    vResult.x = Vector::Select(vY, vRight, Vector::Constant::Select1110);
    vResult.y = Vector::Select(vZ, vUp, Vector::Constant::Select1110);
    vResult.w = Vector::Constant::IdentityR3.v;

    return Matrix::Transpose(vResult);
}