did some digging and the problem with vertex arrays on ATI is all to known it seems ATI uses there own vertex array extensions which renders just as fast as nvidia BUT you will need a whole different set of extensions which are not compatible with standard opengl extensions as pr this thread. http://www.rage3d.com/board/showthread.php?t=33628457
my personal opinion is this is fubar and theres no way im going to write two set of extentions + checks because some gfx card producer cant keep to standards.
vertex arrays have been part of opengl for allmost a lifetime for pete's sake arghhhhh. rant of.
ATI issue because they are "doing it wrong", or failure of openGL to adopt the extensions during the past 10 years? Either way, maybe devs would still have to write it two ways.
Im starting to feel reverted to 3DFX days but atleast there glide api had a wrapper for opengl calls
Hard for opengl to adopt a nonstandard extention from a propriarity driver (not like its opensource or atleast openstandard so ouch )
how would you like something like this if (ATI) glVertexArrayATI(HAH) else glvertexArray(HUH) looks silly doesnt it ?
but if im going to do it at all, im going to wrap those extentions with the opengl standard names if ATI, or else i would have to rewrite the entire thing.
That's an ancient extension and it's long since superceded by GL_ARB_vertex_buffer_object. It's worth noting that NV had GL_NV_vertex_array_range roundabout the same time, which did much the same thing.
I wouldn't even bother using VBOs with that engine by the way; it needs a fairly heavy rewrite first.
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Hmm not sure which engine you refer to ? but if its mine/yours then yeah. I probably made a mess when i converted everything to VertexArrays (the widget and gl draw functions use there own function "derived from old pqer code"). Ill probably end up using your later version from Q2 which is much cleaner to look at also from a code perspective.
Berserker q2 has ARB settings in the video menu, still vendor-specific. Runs fast on ATI. Strangely the "generic" mode produced better rendering quality than "Radeon" settting for me.
Alright so the bloom was quite buggy. Looked fine while I was standing still but as soon as I moved it would glitch a ton. Other than that, i had one other big problem. Whenever alt tabbed out of. you can't re-open it and your mouse is still locked.
the alt-tab problem has been there since... forever. not really sure what causes it but the vid code was changed a lot by mh before i took over. also one of the causes im having a hard time getting the video menu working.
the bloom code is using some old kmquake2 code i modified a bit to fit Q1 its not subtle like mh's later versions and probably looks odd in places (blooms stuff that should not be). im planning to use a better version by mh soon.
If someone wants a look at the code and maybe want to help get the remaining buggers out let me know.
Ok bloom fixed (viewport problem i had the x,y coordinates set to glx,gly values but they need to be 0,0).
alt tab still needs a fix as well as a problem with the cosonle screen going out of sync when changing resolutions.
Btw the fragement shader backend for liquids is also able to do caustics but im having a few problems getting it to work correctly.
Probably i setup the chain incorrectly loosing track of where to put what in order to have a fallback to normal caustics if the gfx card used is to old to do them.
ATI uses there own vertex array extensions which renders just as fast as nvidia BUT you will need a whole different set of extensions which are not compatible with standard opengl extensions as pr this thread. http://www.rage3d.com/board/showthread.php?t=33628457
but atleast there glide api had a wrapper for opengl calls 
looks silly doesnt it ?
but im having a few problems getting it to work correctly.