Driver-supported DirectX

[H. Verbeet]

On 23/11/2007, Stefan Dösinger <stefan at codeweavers.com> wrote:
> Am Freitag, 23. November 2007 12:25:34 schrieb H. Verbeet:
> > Just to add something to that, most of the issues that are there are
> > with older versions of Direct3D and fixed function. The more modern
> > functionality is relatively easier to translate  because D3D and GL
> > simply expose the programmability of the hardware.
> Not quite, there are a few issues at shader level as well. One issue that
> comes to my mind are the 10 varyings vs 8+2 colors in opengl. It is a driver
> limitation actually, but encouraged by the GLSL spec. An architectural
> problem is that OpenGL does not support an up to date assemler shader
> interface. And all shaders are compiled and linked at runtime, causing a
> short rendering freeze whenever a new shader is used.
>
Well, sure there are issues, but generally those are easier to fix
than in fixed function. I don't consider the lack of an asm interface
much of an issue... it wouldn't correspond directly to the hardware
anyway (and neither does d3d shader asm). Linking time *is* an issue,
but I suspect GL3 will help a bit there.

> > It may be useful contacting the nouveau (open source NVidia 3D driver
> > reverse engineering project) development team to see if they can add
> > OpenGL extensions for DirectX functionality.
> This sounds like a nice idea, but in reality we've been talking about getting
> various X11 or opengl extensions added to $SOFTWARE and it never happened.
>
It would probably have to wait until nouveau actually properly supports 3D.