View Single Post
Old 08-02-02, 07:53 PM   #34
Sittin in the Sun
Nutty's Avatar
Join Date: Jul 2002
Location: United Kingdom
Posts: 1,835
Send a message via MSN to Nutty

how is that good? wouldn't you rather the game have high poly counts that may be unusable for now, but will be usuable later?
The problem with high poly counts in the doom3 engine is as follows.

The silhouette finding algo for the shadow volumes is done on the cpu. And it has to be done every time a light source that is affecting the object is moved. Increasing polys in Q3 only affects the GPU speed. Increasing polys in Doom3 affects the CPU performance too.

Also, for every light (and it supports alot more than 1 light as someone previously said), you have to perform 2 passes on the model just for the shadow volume. Thats per light! Additionally to this you have the per-pixel bump-mapping also. So we're talking minimum 3 passes per object per light.

So if you doubled the poly count, you'd actually get a 6 fold increase in poly throughput per frame per light. Thats why the models are very low poly.

NV30 will bring double sided stenciling, which will allow you to do shadow volumes in 1 pass, instead of 2. Which will be nice.

Nutty is offline   Reply With Quote