'Exophase' said:
The IMGTec employee who posted here (whose handle escapes me at the moment, I'm afraid [ed: xmas]) told me that the overdraw elimination is 100% efficient not just on a per-tile level but on a per-pixel level as well. I take it this only applies to opaque pixels, but I don't think having the ability to render translucent pixels is hindering the rendering of opaque ones. I think many scenes will have little or no translucency in textures, so this isn't totally irrelevent.
indeed, handling of translucent pixels is not hindering the handling of opaque ones (and TBDRs have many good things to offer to translucent pixels too*), but you underestimate the relevance of the translucent pixels:
1) every multi-pass primitve (less relevant these days, but still not extinct, particularly on architectures where the shader op count per pass is limited) is essentially a 'blending' one, whether it is translucent in its first pass or not.
2) statistically, entirely-opaque scenes almost don't exist in nature, at least not in the context of the average modern video game. even if only for all the fancy full-scene post-processing effects popular today. then, factor in 'momentary peaks in translucencies' like explosion fx and etc particles, and you can see how an 'opaques-only optimised' architecture could pose a challenge. in contrast, a raw-fillrate-optimised architecture could present a better ballance.
* like gargantuan bandwidth to the on-chip tile buffer, removing the onus from the IMR's read-modify-write blending ops (some IMRs like xenos do another trick there). also, older implementations of the PVR architecture had free per-pixel translucencies depth-sorting, which allowed for perfectly-correct arbitrary-complex translucent meshes - something which has traditionally been a PITA for IMRs.
The bottom line is that there is no point attempting to duplicate code running on 8800 GTX on Pandora.
Beyond demos , I don't think you can realistically expect normal mapped worlds with full screen blooms and other effects on Pandora.
Basic multitexturing with static shadow maps will most likely end up being the most efficient and visually pleasant way to render relatively complex worlds.
