This patch implements these extensions: GL_ARB_texture_env_combine GL_EXT_texture_env_combine GL_ARB_texture_env_crossbar
G400 or better needed obviously.
First let me say this: WOW. I am very impressed. I'm impressed that you changed your mind about the viability of implementing this on MGA, and I'm impressed that you came up with such a clean solution so quickly.
[snip]
I made the mapping between OpenGL args and hw args flexible. This way it doesn't matter in which order the user specifies the arguments.
That's one of the tough parts of MGA. The argument ording to the combiners is very inflexible. I like the way you did this.
Hw can't support dot3 stuff. Also RGB_SCALE and ALPHA_SCALE only work fully with GL_MODULATE. GL_REPLACE can't support this at all the others support only a value of 1.
Dot3 is one of the truly frustrating things about the G400. It has all the hardware to do it. It has the MODULATE arithmetic followed by the ADD in almost the right way. Too bad they didn't think to wire the ADD logic that way. :( Of course, at the time they thought EMBM was going to be the thing of the future...
On GL_REPLACE, it can handle scaling in most cases. You just have to program the alpha input to be 1, select the correct color input, and use the modulate with the correct scale. Of course, I'm not sure that GL_REPLACE with a non-unity scale is a common enough case to go to that much effort for. Dunno...
So far I've only tested with an emboss bumpmapping sample from ATI. Good news is that it looks ok :) It uses GL_MODULATE, GL_REPLACE and GL_ADD_SIGNED. Are there any other good tests I could try?
There's always glean. If that says it's okay, then I'd have a fair amount of confidence in it. You may want to code up something simple that will hit some of the cases that you know the hardware can't do. We want to be sure that it does a SW fallback when it needs to.
You may also want to add an env var / config variable to disable these extensions. There are some apps that may be slower (because they only hit the SW fallback paths) with the extensions than without. I seem to recall that Matrox's Windows drivers had a check-box in their config tool to enable / disable tex_env_combine support. You'll probably want to wait until after the config file stuff is merged to do that, but it's your call. This is your baby, afterall. :)
On a side note, have you looked at ATI_texture_env_combine3? When I was looking at ARB/EXT_texture_env_combine some months ago, it seemed that the G400 could do quite a few cases in the ATI extension as well. The ATI extension adds 3 modulate-then-add modes. As long as there were only two "different" inputs used, the G400 could do it. There are a few apps (e.g. UT2k3) that like to use that extension.
http://oss.sgi.com/projects/ogl-sample/registry/ATI/texture_env_combine3.txt
------------------------------------------------------- This SF.Net email sponsored by: Free pre-built ASP.NET sites including Data Reports, E-commerce, Portals, and Forums are available now. Download today and enter to win an XBOX or Visual Studio .NET. http://aspnet.click-url.com/go/psa00100003ave/direct;at.aspnet_072303_01/01 _______________________________________________ Dri-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/dri-devel
