More carmack love :)

Zitat

We actually screwed up at E3 -- we should have been running it at high quality settings (uncompressed textures, anisotropic filtering), but we were chasing some problems the first day, and it got set back to medium quality. The problems had gone away, so we left it that way, rather than risk changing it back.

Nur mehr sick

Doom III- the revolution.

[QUOTE]I'd asked JC three specific questions. Here are his answers :

Regarding the seemingly low-poly models (from the screenshots), shadow volume lighting and how they relate to his engine. I said that his engine may slow down if higher polies are used and if ATI's TruForm may help out :

The game characters are between 2000 and 6000 polygons. Some of the heads do look a little angular in tight zooms, so we may use some custom models for cinematic scenes.

Curving up the models with more polygons has a basically linear effect on performance, but making very jagged models with lots of little polygonal points would create far more silhouette edges, which could cause a disproportionate slowdown during rendering when they get close.

TruForm is not an option, because the calculated shadow silhouettes would no longer be correct.

Regarding higher precision rendering on a Radeon 8500 vis-a-vis a GF3/GF4Ti. I stated the obvious difference (like JC didn't know it, bleh!) in this aspect between the two and how, during combining, the 8500 allows for better dynamics in lighting. The question was if this would be an influence in how DOOM3 would look depending on the board used :


At the moment, it has no impact. The DOOM engine performs some pre modulation and post scaling to support arbitrarily bright light values without clamping at the expense of dynamically tossing low order precision bits, but so far, the level designers aren't taking much advantage of this. If they do (and it is a good feature!), I can allow the ATI to do this internally without losing the precision bits, as well as saving a tiny bit of speed.

Regarding his publicly-stated (but somewhat veiled) "complaint" (re GF3/GF4Ti vs 8500) about multiple passes based on the number of texture accesses he needs (7, as he stated) and that although the 8500 should, in theory/based-on-specs, be faster but somehow the GF3/GF4Ti is "consistently" faster even with 2 or 3 passes (compared to the single one on a 8500). My question was whether the 8500 may have a problem in terms of latency even if its single shader does all the work (bandwidth savings accepted as well) :


No, latency should not be a problem, unless they (JC's talking about ATI's 8500) have mis-sized some internal buffers. Dividing up a fixed texture cache among six textures might well be an issue, though. It seems like the nvidia cards are significantly faster on very simple rendering, and our stencil shadow volumes take up quite a bit of time.

Several hardware vendors have poorly targeted their control logic and memory interfaces under the assumption that high texture counts will be used on the bulk of the pixels. While stencil shadow volumes with zero textures are an extreme case, almost every game of note does a lot of single texture passes for blended effects.

I have more questions for JC (based on his replies, solely) but I will wait a day before sending them off to him in case some of you also have some questions for him... I will wait a day and include whatever (good and reasonable, as I deem them to be) questions you folks may have... and hope he replies to me again! Questions such as "Do you have a NV30?" (he doesn't, or didn't leading up to E3, btw ) or "If you have a NV30, how does it compare to the R300?" will be skipped.[/quote]

so sick!