I have an XNA application (a force based visualisation of some circles) that I've implemented zooming and scrolling in, thanks to this guide.
Before I had the camera implemented, I had picking implemented (click and drag a circle to move it around). However, after the camera transformation I'm struggling to match up my mouse X,Y coordinates with the post-transformation coordinates of my circles.
I attempted to multiply my mouse X,Y vector with my camera transformation matrix. Given a mouse click at (356, 492), after translation I get (713,300), but my objects are around (-1000,900) or so.
So, given a mouse click in local X,Y coordinates and circle locations in post-transformation X,Y coordinates, how do I match them up?
(If it's needed, my VS2010 project is here.)