   Reversing perspective effect
  If I wanted to reverse the perspective effect how would I do this?I know to generate a perspective view it's:x = d * x / z;but how would I reverse it?   
  If you don't want it to happen, you should check out orthographic projection.  Orthographic projection doesnt make the perspective effect happen.If you do want it to happen but for some reason really do just want to reverse it, if you know d and z then some simple algrebra should be able to help you out (:If for some reason it doesn't, can you give some more info?   ;  What I'm trying to do is project ray end points, so they would be fanned out more the farther away from the camera instead of fanned in like regular perspective would do... so I need to transform the ray end points with reverse perspective I think.   ;  Uhm...couldn't you just invert the projection matrix?   