Originally Posted by Cheimison
"I *think* that one of the great misconceptions about technology, especially regarding graphics, is that it's revolutionary rather than evolutionary. Remember how people complained about Thief3's and DX:IW's performance? How they performed worse than they looked? I think the *only* difference between those engines and Doom3's is that Doom3 uses specular light maps on everything, whereas those other two don't. Meaning that if you turn off specular in Doom3, you end up with a game that looks the same as the other two, with similar performance."
Just because engines have the same features doesn't mean they perform those features as well. Pre-Release IW did indeed have all the general features of the D3 engine in name, but D3 has defacto superior quality of those effects. Also the polycounts in D3 are WAY higher than those games.
Depends on the engine take the quake 3 engine now and put in per pixel lighting and all shadows casted are volumetric you will end up with Doom 3. The Q3 engine can also handle the polygon counts too. The reason for the rewrite was probably to make the code more portable and easier for others to read.
The Source engine is very similiar to the Doom 3 engine as both have the same inharent restrictions because they are both built on a BSP tree.
The new revolutionary engines are Stalker and Crytek, this is why both these engine can do indoors equally well as Source and Doom 3, but when it comes to outdoor rendering they are unmatched. They don't use BSP trees. The base engine for terrain rendering uses either octtrees or polysoups. By using these methods the programming of geometric complexities increase quite a bit.