Doom 3 engine

[Duane]

This is a question about the Doom 3 engine. When playing with a friend, we were hacking the models, and I was astonished to find out that the models were thousands of polygons, not to mention the bump mapping they must have had to do. Running the game again, and checking out things like quality and stuff. how is this still playable? The game is less like an actual game, and more like a cgi film or something. :shock: I take it they use directx, does this make it possible? if so, I'll just switch to windows now.

[DoG]

Thousands of polygons is nothing special. They use some LOD scheme to reduce the polygon count at runtime for lower-end systems. And it is not playable at hi-res on low-end systems.

[Duane]

hmm
*wonders how to impliment*

[OneSadCookie]

it uses OpenGL, and it's not really playable on much less than a Radeon 9800. ATI says that the Radeon 9800 should be able to draw 500,000 pixel-shaded polygons per frame at 60Hz, and I doubt Doom III quite gets to that level.

[Duane]

Requirements (http://www.doom3.com/sysreq.asp). it uses DirectX 9.0

[OneSadCookie]

It may use DirectSound and DirectInput, but the graphics are OpenGL.

[AnotherJake]

Thousands of polygons is nothing special. They use some LOD scheme to reduce the polygon count at runtime for lower-end systems.
And high-end systems as well. I read somewhere ( I may be full of it here ), that JC came up with some new way of reducing LOD with distance. I haven't seen Doom3 yet so I don't know if there is any geometry popping, but I've heard it's good. The Halo2 distance LOD works very well IMHO but there is some popping that catches my attention once in a while.

I've heard they're also using normal mapping to fake you out that the geometry is higher than it really is. From what I understand, they first generate *very* high polygon count models to generate the normal map with, and then that map is downsampled as per requirements in the game. They don't use the original high poly model in the game though. Again, take this with a pound of salt.

[Puzzler183]

Graphics are OpenGL for sure, it's a Carmack engine. But who really cares? OpenGL has more or less the same performance as Direct3D. And yeah, with level of detail stuff, it really isn't that much - my new graphics card is said to push 638 million vertices per second - or about 10 million per frame at 60 frames per second.

[jessimko]

According to http://code0range.net/node/374, "normal maps are encoded in RGB values which are used to indicate which direction the normal faces relative to the face of the polygon it is mapped to."

It's almost as if you're carving more detail into a model with a spattering of pixels, instead of polygons. The normal mapping in Doom 3 makes it look like the models have far more polygons than they actually do; although the graphics are great, the segmented contour of a character reveals its low poly count. Check out the top of this guys head:
http://www.insidemacgames.com/images/doom3_015_large.jpg
it comes to a point :)
It's cool how normal mapping can make up for such a lack of detail in the geometry.

Here's a screenshot of an Unreal 3 character... looks like another big improvement in graphics technology: http://www.unrealtechnology.com/screens/p_bezerker.jpg

[AnotherJake]

Thanks for the links jessimko! Speaking of normal maps, I just stumbled upon this site (http://www.monitorstudios.com/bcloward/resources_tutorials.html) yesterday. I haven't had a chance to really dig into it, but it appears to have a lot of info on the subject as well.

[kelvin]

Check out the top of this guys head:
http://www.insidemacgames.com/images/doom3_015_large.jpg
it comes to a point :) The back of my head comes to a point :p