Ok, it’s too late and I just can’t get my head round this.
I have a perspective projection onto a texture which is parallel to the screen. The camera is straight onto the texture and moves parallel to it. When the camera moves I need the amount the texture will move on the screen e.g. if the camera moves right from X=0 to X=16 then the texture will move by some number (Y) of pixels.
I know this should be easy and it should be similar to a question I asked before before (here), but now I can’t get any of my numbers to work (for that question or this and yet I’ve got a bunch of numbers I worked out from that answer that I can no longer understand…must be old age).