Fixing backprojection

Well this’ll be an old timer question, I’m doing this on fixed function because the base I’m working on is quite old, and I don’t want to recode almost all of it.

I’m trying to add shadow mapping to my projective light, it works fine on the depth map side, but I get the well expected back projection problem, and I’m having trouble solving that. I know that my blending and all other texture units are set up fine, I’m just having trouble with the 1x2 pixel 1D clipper texture, that’s explained here:
http://www.cbloom.com/3d/techdocs/shadowmap_advanced.txt

My problem is, I have no clue how I should set projection up for the clipper texture. I’m not very good when it comes to any kind of projection or matrix work. I was wondering if anybody could help me on this matter. I’m totally lost here. From what I understand I need the Z coord to be mapped to the S texture coordinate, but any of my attempts didn’t work. Does anyone have an example of this working, at all?

Thanks.

You might check out this thread. Particularly the last few posts:

This problem was actually “fixed”, it wasn’t the problem I had haha. Thanks for replying though, the problem was something else that I had gotten through.

The real problems are being discussed in the “Shadow mapping problem” thread.