It looks like Sonicadvance1's r507 changes helped ATI cards in OGL a bit.
WinXP 32-bit Radeon HD 2400
Before his code revision in r505
And after in r525
It may not look like much to some, but I think it did help. Obviously it's not perfect or ready to be played, but he is on the right track I think.
WinXP 32-bit Radeon HD 2400
Before his code revision in r505

And after in r525

It may not look like much to some, but I think it did help. Obviously it's not perfect or ready to be played, but he is on the right track I think.