Advertize software emulated Direct3D features?

[Stefan Dösinger]

Am Freitag 27 April 2007 09:02 schrieb H. Verbeet:
> On 27/04/07, Stefan Dösinger <stefan at codeweavers.com> wrote:
> > I am working on vertex blending support for WineD3D. First I implemented
> > it using GL_ARB_vertex_blend in hardware, an extension that is
> > unfortunately only supported by ati cards, and not nvidia. So I took
> > Frank Richter's started software emulation for vertex blending, with that
> > it works everywhere.
> >
> > The question is wether we should report support for this feature in our
> > d3d caps. Because it is software emulated it forces wined3d into the
> > drawStridedSlow path which is, well, slow. Enabling this may cause a game
> > to choose this slower render path over something else, like vertex
> > shaders. On the other hand it can get applications run that wouldn't work
> > without this feature.
> >
> > For vertex blending it doesn't matter much. Its hardly used, and all
> > games using it provide a vertex shader path too and prefer it(exception
> > are the dx sdk demos). The other alternative the apps have is to either
> > disable the feature entirely, thus have lower graphics quality, or
> > calculate it themselves, which won't be slower than wined3d doing it. So
> > I think we should advertize vertex blending, but the general question
> > remains.
> >
> > What do you think?
> >
> > PS: Ideally we'd have a vertex pipeline replacement in form of a vertex
> > shader, but that wouldn't invalidate the point of this since not all
> > cards support vertex shaders. (And I personally dislike the idea of a
> > pipeline replacement for this reason).
>
> I'd rather not report caps we don't properly support, for the reasons
> you just mentioned. As for the pipeline replacement, I don't really
> see the issue. There are lots of things that older cards don't
> support. If it provides advantages for newer cards, I don't think that
> should be held back because older cards don't support it.
I take that "It won't be slower than the app emulating it" back. The 
skinnedmesh demo runs twice as fast with the apps "software skinning" than 
with wined3d's emulation. I have to investigate why that happens, the mesh 
doesn't look worse with the sw skinning.
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