Re:This can only work for some games (Score 1)

I am also a game programmer who has written both VU microcode for the PS2 AND vertex shaders for the PC and my assertion is that the while you can certainly expose some level of platform specific features to your graphics effects programmers via extensions to a graphics API, it would be a serious mistake to expose anything on the level of assembly, which is in essence what you are suggesting. Do you force the other programmers dealing using your graphics code to set registers and build DMA chains themselves using inline assembly? Or do you attempt to encapsulate those functions in a clean interface and advise limitations on rendering and texture transfer order. Even vertex shaders have their low-level functionality encapsulated in a clean and flexible API.

I will bring up Criterion's Renderware yet again. Their system nearly completely encapsulates hardware functions, yet also exposes hardware specific features for the various consoles via extensions to the programming interface. Sure if you have a large in-house team that ONLY wants to develop for the PS2, you may have to create your own system from scratch if a system like Renderware doesn't support your wacky ideas for the IPU, but these are the rare exceptions. Take a look at the number and quality of titles Criterion's Renderware, you can get high performance out of cross-platform libraries.