Game Development Stack Exchange is a question and answer site for professional and independent game developers. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I am trying to implement dual-pass alpha sorting using Ogre material scripts, as part of my debugging attempts I want to compare two PIX captures, but when I attempt to debug a pixel in PIX, previously working 'geometry' is not displayed correctly.

My 'reference' blended geometry which works consistently, consists of a simple box with a translucent material, sitting over a set of opaque primitives. In my app this displays fine with the 'smoked' box tinting the objects/pixels behind it. When I load up my app starting through PIX this continues to work, but once I load a capture taken from this in PIX, it no longer blends the pixels and instead culls them.

I know it is PIX because in the debugger tab, I see the initial value of the pixel I am debugging is the correct blended colour, but the final frame buffer value is the darker incorrect colour - its as if PIX is 're-rendering' the shot and doing it wrong!

Could anyone suggest a reason for this behaviour?

share|improve this question
up vote 0 down vote accepted

If the reference rasterizer displays it correctly, then your code is correct and it is a bug in PIX.

share|improve this answer
Hi, It is a rare day when I actually get to attribute problems to someone else's code! ;) I have managed to implement dual-pass alpha sorting, short of Ogre doing something clever along the lines of combining multiple frames (would Pix pick up on that) I don't see what else it could be. I am glad someone else confirms it, thanks! – sebf Aug 15 '11 at 7:31

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.