Talk:Unified lighting and shadowing

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[edit] Slightly inaccurate...

"Doom 3 uses a unified model that generates the lighting and shadows for everything at run-time. This means that any lights will affect the whole scene and not only certain parts. This may include self-shadowing via shadow volumes, where characters can cast shadows on themselves, for example the shadow cast by the marine's chin onto his neck."

Firstly, this statment is not an accurate definition, several previous games have done this, including Quake 3 which is quoted as using an 'old model' here. Also, in Doom 3 the shadow volumes can be pre-generated by the map editor for the static lights casting from static geometry, the shadows are only recalculated for the dynamic objects or dynamic lights. I replaced it with the more accurate description of a unified lighting model:

"Doom 3 claims to use a unified model, which renders every triangle using the same lighting mechanism, regardless as to whether it originated from a model, or map geometry. This is not strictly true as some models are marked with a 'don't self shadow' flag, custom material shaders can allow different lighting mechanisms to be employed on different surfaces (most often a reflective cube map effect), and the point sprite effects (such as explosions) are totally unlit. A renderer using a truly unified lighting system would use an identical set of lighting calculations for every pixel on the screen and would not make such distinctions, although Doom 3's lighting is certainly far 'more unified' than previous games, there is still much more which can be done on recent and future hardware to improve the consistency of lighting in games."

"Doom 3 doesn't use OpenGL's built in system, instead, it uses its own system which gives better quality and more accurate illumination than OpenGL's current lighting model."

I altered this a little, since the OpenGL lighting model isnt likely to ever change to ensure backwards compatibility, so I replaced 'current' with 'default'.

"Shadow volume - the general technique for dynamic shadows"

Shadow volumes are ONE technique for dynamic shadowing, a more popular technique is infact shadow mapping, which doesnt rely on any volume generation, but instead is based on depth information rendered into a cube map for a point light, or regular texture for a projected light, from the point of view of the light source. Another, but less important (due to high computational cost) technique is raytracing.

--Jheriko