vp performance

[JanHH]

Hello,

do vertex programs and per pixel lightnig using NV register combiners cost any additonal performance compared to standard OpenGL vertex lighting? If rendering in a single pass? Are triangles drawn in a "simple" mode faster drawn than triangles that use register combiners and vertex programs, or is the hardware (GF 4/5) able to do this "on the fly" without additonal costs?

Thanks
Jan

[Jan]

Vertex programs are usually for free, since the chips are very fast.

And i think you get the register combiners for free, as long as you only use 2 combiner stages. If you use 3 or 4, that´s a BIG slowdown (but for PPL you don´t need that much).

However i am not so sure, if you really get the first 2 reg. combiner stages for free, so, if that´s not the case, than it´s a lot slower than vertex-lighting.

Additionally to that, for per-pixel lighting you need more textures (for the attentuation and maybe bumpmapping, etc), and that will slow you down even more.

I think in general it´s save to say, that vertex-lighting is much faster than PPL.

Jan.

[JanHH]

do you know a good tutorial about register combiners (a tutorial that is step-by-step and understandable)? I managed bump mapping with ARB extensions, now would like to go on to register combiners but again do not find any really good tutorial (concerning the ARB extension, the one from paul's projects finally helped me, really good ).

[JanHH]

and what about GL_TEXTURE_SHADER_NV? another way to do ppl/bump mapping? I guess this is outdated?

[JanHH]

or give me some code .

for example, very simple situation, diffuse bump mapping, texture unit 0 contains the normal map, tex unit 1 the normalization cube map and tex unit 2 the color map (simply decal, not modulate). assume that this is already set up, as well as the tangent space transformation. what is the combiner set up code for this?

thx

Jan

[ScottManDeath]

you should check nvidias developer site

there you find a lot of whitepapers and also demos/source code for their extensions. the CG sdk is also very interesting, beacause it contains also "the old demos" without cg


like following: http://developer.nvidia.com/object/P...ping_Tech.html http://developer.nvidia.com/object/b...combiners.html

[Jan]

If you have trouble understanding how the register combiners work, than check this paper out:
http://developer.nvidia.com/object/combiners.html

It is a very technical and very detailed description of the extension and makes it very easy to understand how to set up the stages to perform whatever you like.

It is my #1 reference when i work with the combiners.

Jan.

[JanHH]

I know the nvidia developer site stuff, and the problem is that it is mainly technical descriptions on powerpoint charts with only a few lines of descriptions. It's too abstract, I think. It's not that I do not understand RC at all, but the gap from theoretical knowledge to being able to write some code to use it is stll quite large. So I would appreciate some lines of exampe code for the situation described above. In fact there's one NVIDIA presentation for this, but the code is not OpenGL but for NVPARSE (I think), argh..

Jan

[Jan]

You are lucky, that i have a lot of time and nothing to do.

Since OpenGL.org´s code tags are crap, i put it into a seperate file:
http://www.artifactgames.de/IMAGES/example.cpp

I hope that will help you a bit.

Merry Christmas.
Jan.

[JanHH]

great. thanks a LOT :-).

Jan