Re: [Nel] (no subject)

[Nicolas Vizerie]

Hi Jean-Philippe,
Currently there's support for vertex shaders in NeL (version 1.0 & 1.1, not
2.0), but as we're using OpenGL, we've got to write several versions
depending on the available extensions. The goal in NeL is always to make it
transparent to the end user (like with D3D). In our current project we only
use the 1.1 version and it fit our needs. (2.0 version is only available on
the ATI 9700 & NV30 emulator for now as far as I know)
For now we support :
- GL_NV_vertex_program
- GL_EXT_vertex_shader (provided by ATI, works reasonnably well in the cases
we need)

To do the conversion to other extensions we wrote a vertex program parser
(NL3D::CVertexProgramParse). The input use the nVidia vertex program format.
If required, tokens are converted to the other extensions.
In the near future, we'd like to support ARB_vertex_shader, because it's
likely to be implemented by numerous vendors.
What is needed to do the conversion is to complete the OpenGL driver to
output a vertex program in this format.
Later we may need a conversion to the D3D format if we write a D3D driver.
Here's the state of NeL for vertex shaders..

For Pixel Shader, we currently have limited support : we support
NV_texture_shader and GL_ATI_envmap_bumpmap, but these are more texture
adressing modes than pixel shaders. We don't support register combiners.
What would be great is to have a conversion from a standard Direct3D pixel
shader code to the available extensions (nVidia & ATI), but this may require
a lot of code however.. For now it is not a priority at all, but it is
likely to be implemented in future versions of NeL. A way to implement it
would be to have a CPixelShader class and a smart pointer to it in the
CMaterial class . When not NULL, it would bypass the standard pipeline.
There are other possibilities of course.

If you feel like to implement some of these parts, why not !

Regards,
Nicolas Vizerie
NeL team


----- Original Message -----
From: "neuser jean-philippe" <address@hidden>
To: <address@hidden>
Sent: Wednesday, November 13, 2002 6:38 PM
Subject: [Nel] (no subject)


> Hello everybody
> i learning pixel and vertex shader for a program i have to do for a
> scientific image center . May be i can improve some code for u. may be ...
> Just say me why what you want to improve and wich version of vertex and
> pixel shader you want to support.
> googd bye.
>
>
>
>
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