D3D: Implement vertex blending in drawStridedSlow

[Henri Verbeet]

2009/1/28 Claudio Ciccani <klan at users.sf.net>:
> Why not both?
It doesn't really work that way, you have to justify adding stuff.

> I mean, you could implement a hardware based vertex blending routine
> using a vertex shader and keep the software vertex blending routine in
> case vertex programs are not supported by underlying hardware.
> Actually this is what the patch does: fall back to software vertex
> blending when hardware vertex blending is not supported.
>
I'm fairly certain there aren't a whole lot of cards that don't
support either ARB_vertex_blend or vertex shaders, but do support
vertex blending on Windows.

>> > If I understand, the software-only wined3d backend is dead and gone, so
>> Slightly OT, but we might need to implement software shaders at some
>> point, although that has a rather low priority right now. Would be
>> interesting to see if we could use Mesa swrast for that.
>
> Implementing shaders in software would be terribly slow.
Sure, but that's not a problem, applications that create software
shaders are probably aware of that. Note that this would be for
software shaders as exposed by d3d, not a software implementation of
hardware shaders. We currently run software shaders in hardware as
well, but that imposes some limits on eg. the amount of available
constants. This is unrelated to vertex blending.