In the Radeon driver, TCL is currently enabled by default. However, it seems like there is no guarantee that the same set of vertices will be transformed equally twice, so you get Z buffer artifacts when doing multipass rendering.
I am told that the DRI developers believes this is not a bug, because you should use glPolygonOffset when doing multipass rendering. This is wrong. glPolygonOffset is used when you wish to render polygons in the same plane as previously rendered polygons using _different_ vertices than those of the previously rendered polygons. However, if you render two polygons with exactly the same vertices, the pixels of both polygons should have exactly the same Z values. glDepthFunc(GL_EQUAL) becomes pointless with the current behavior. This tutorial at SGI describes multipass rendering without mentioning glPolygonOffset, but recommending the use of glDepthFunc(GL_EQUAL): http://www.sgi.com/software/opengl/advanced97/notes/node67.html This extension specification also uses glDepthFunc(GL_EQUAL) to perform multipass rendering: http://oss.sgi.com/projects/ogl-sample/registry/ARB/occlusion_query.txt Hence TCL must either be disabled by default, or it must be used consistently. -- Morten Hustveit, http://www.ping.uio.no/~mortehu/ ------------------------------------------------------- This SF.net email is sponsored by: The SF.net Donation Program. Do you like what SourceForge.net is doing for the Open Source Community? Make a contribution, and help us add new features and functionality. Click here: http://sourceforge.net/donate/ _______________________________________________ Dri-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/dri-devel
