void Camera::BuildViewMatrix(const Maths::Vector4 &position, const Maths::Vector4 &lookAt, const Maths::Vector4 &up)
{
Vector4 viewDir = lookAt - position;
Vector4 viewSide, viewUp;
// store values
m_up = up;
m_position = position;
m_lookAt = lookAt;
viewDir.Normalize();
viewUp = up - viewDir * up.DotProduct( viewDir );
viewUp.Normalize();
viewSide = viewDir.CrossProduct( viewUp );
// setup inverse rotation matrix
Matrix4 rotation;
rotation.SetRows( viewSide, viewUp, Vector4( -viewDir.X, -viewDir.Y, -viewDir.Z, -viewDir.W ), Vector4( 0.0f, 0.0f, 0.0f, 1.0f ) );
//transform translation
Vector4 invPos;
Matrix4::Transform( rotation, position, invPos );
m_inversePosition = -invPos;
// build view matrix
Matrix4 view;
Matrix4::Multiply( view, rotation, m_viewMatrix );
m_viewMatrix( 0, 3 ) = m_inversePosition.X;
m_viewMatrix( 1, 3 ) = m_inversePosition.Y;
m_viewMatrix( 2, 3 ) = m_inversePosition.Z;
m_viewMatrix( 3, 3 ) = m_inversePosition.W;
m_viewDir = viewDir;
}
void testCrossProduct(){
Vector4 a;
Vector4 b;
a.SetVector4(1,2,0,1);
b.SetVector4(2,1,1,1);
Vector4* c;
c = a.CrossProduct(b,a);
c->DisplayVector4();
delete c;
}