Re: [Nel] Direct3d driver

[Cyril 'Hulud' Corvazier]

Hi Mårten,

> I've started implementing a Direct3d driver
> for NeL3d. If someone already done any part
> on such driver or has some ideas, tips or
> anything, please contact me!

We will be happy to help you in your work.
We had several internal discussions about implementing a Direct3d NeL driver.

Here some comments:

- The Nel driver interface has been designed for a futur d3d implentation.
- D3d implementation should be done in DX v8.1 in pure hardware mode (state 
cache should be done in the NeL driver).
- It is recommended to fit as close as possible the opengl implementation 
(driver private informations system
for hardware vertex buffer, textures and material - states / textures 
modification cache).
- The NeL vertex programs are written in a subset of the NVidia Opengl vertex 
program language specification.
This subset should be easily parsed and translated in DX vertex program. Check 
the NVidia document about
difference between DX / opengl vertex program "Vertex+Shader+API+Diffs.pdf" and 
"nel/src/3d/vertex_program.h"
- Potential prb: the software vertex buffer in directx are allocated internaly. 
In opengl, software vertex buffer are allocated
by NeL. The NeL driver interface doesn't allow the software vertex buffer 
pointer to be handled by the API.
One temporary solution is to use DrawPrimitiveUP, but it can be a performance 
problem in the future.
- Potential prb: empty texture stages have not the same result in OpenGl and DX.

We are ready to modify the NeL driver interface if a problem can't be solved 
efficiently.

Regards,

Cyril Corvazier