Originally posted by mm
?
Bump Mapping is a technique to give an object more detail without adding more polygons. It\'s a way of simulating small bumps on the surface by changing the way the light effects are calculated. A bump will usually have one side that is bright from a light source while the other side is dark because it is on the shadow side. Bump Mapping modifies the light calculations to make this happen. So it\'s important to know that Bump Mapping does not change the surface of the object it only changes the way light is reflected by the surface....
Bump Mapping is something very good and it could be the reason why ND are trying to implement it on their next game...with an inferior result(compared to the XBox)...and wasting power you could use for physics and animations...for example...
...why? because it gives you a very little advantage graphically?... XBox games in the near future will have great bump with smooth frame/rate!
bump mapping has been around for PC games for years, and i turn it right off
do you know why? ..you\'re referring to hardware like voodoo2...performing the perturbed Environment Bump Mapping..
Perturbed Environment Bump Mapping is a very advanced way to do Bump Mapping,it can handle both the light effects and can also handle bump mapping combined with environment mapping. Unfortunately no hardware(in Voodoo2 era :eyemouth: ...not too sure about it...) supports the special texture lookups needed. Disadvantage is the fact that for every frame a new environment map may be needed due to moving lights...and some of this can be done by UV perturbations (shifting of the map).
Perturbed Bump Mapping is a three pass technique. You first need to combine the bump map and its shifted version. The result is a lightmap that needs to be combined with the texture map in the third pass.
On Voodoo2 hardware this technique halves the fill rate so it is not for free. The combination of the bump maps can be done in one pass using the two texelfx processors but the hardware still has to combine the lightmap with a texture map and this has to be done in a second pass. This technique also needs to CPU to calculate the shift for the bump map. For correct 3D effects the shift of the texture co-ordinates has to be recalculated for every polygon and this can put quite a bit of strain on the CPU.
The NV2a of the XBox is not a voodoo2...right? ...and even PVRSG supports this technique in hardware resulting in almost no extra CPU use... and fill rate is also hardly affected...