per-pixel lighting

nope, it is not that easy.

per vertex lighting is a standard opengl feature, per pixel lighting is not. if you want to implement it, you have to do some texturing tricks (at least attenuation mapping and dot product mapping) or write your own pixel shaders (fragment programs). you can use the standard lighting features (for attenuation e.g.) in combination with bump mapping, but you do not have to.

by the way, per pixel lighting and normal mapping is not the same. you can have per pixel lighting without bump mapping. but if you use dot3-bumpmapping, you almost have per pixel lighting and therefore it is quite easy to use it together.

you might find some useful papers concerning both topics at developer.nvidia.com!

thanks for the reply!!!
For use a per-pixel attenuation I should use the normalized cube-map, multitexturing...etc?
I saw some code...but I'm studing it!!!Thanks again!!!

To understand some basic concepts about per-pixel lightning read Ron Frazier's articles
http://www.ronfrazier.net/apparition/index.asp?appmain=research/per_pixel_lighting.html


Technically, basic per-pixel lighting can be implemented with just multipass rendering and texture coordiante look up algorithms (without any GPU help). However this will obviously not be very fast if you have complex scenes and multiple lights. Thats why there are extensions that have been implemented in graphics cards that can speed up the process. (Nvidia Texture Combiners for example, dot3 product). Additionally now with pixel shaders per-pixel light looks even better because calculations can actually be done per fragement (pixel) instead of just texture lookups, and also you can even do per-pixel material effects, such as normal maps, and specular maps, etc.

This is the same article I've read!!!
If I would a per-pixel light indipendent from the video card, I should use a pixel shader,right?

Quote:

Original post by _biobrain_ This is the same article I've read!!! If I would a per-pixel light indipendent from the video card, I should use a pixel shader,right?

Yes, but remember that graphics cards vary widely in the features you can expect. To implement per-pixel lighting, you're probably better off using a type of shader language, like NVIDIA's Cg (which is Microsoft's HLSL). Cg works on a wide variety of graphics cards, and abstracts a lot of the complexity of working with different types of graphics cards. You can find a lot of information on basic lighting at NVIDIA's website, and with the Cg runtime, which has a heap of example programs. OpenGL 2.0 will have it's own shader language, GLSL. You can use it now, but you will need a very up-to-date graphics card, as it's not compatible with old hardware (someone correct me if I'm wrong on this; I don't have much experience with GLSL)...

you're correct about GLSL, it requires at least a DX9 class graphics card (ATI R300 and GFFX series of cards)