Kool! Thanks! I can't try it out now, but I sure will soon!
Btw, that thing with the GL and GLU units in FPC is quite interesting! Now I'm warned! lol
Also, when reading that other thread, I learned about GluUnProject, which is the opposite of what I asked, right?
I hadn't even asked cos I thought it was not possible to do that, since a point in the screen is an infinite line in a 3D matrix...
But obviously (and fortunately!) ppl are a lot smarter, and they found a way! I saw it requires to input the window coordinates plus a Z coordinate.
So that Z coordinate, is it the depth out of the screen (so negative for into the screen) regardless of the transformations you have made to your matrix; is it like the depth buffer you talked about, in which case I guess it would be positive into the screen, right?; or is it the z coordinate of your matrix?
If it's the latter, then what if you rotate the matrix so that the z axis is 'parallel' to the screen, wouldn't that make it undefined?
thanks for this extended help! :wink: