[Mesa-dev] [Mesa3d-dev] r300g: hack around issue with doom3 and 0 stride

[Keith Whitwell]

I'd like to get rid of the zero stride concept and require the state  
tracker to either turn those values into proper constant (easy now we  
can bind >1 constant buffer) or use instancing to get the same effect.

Keith


On 11 Apr 2010, at 00:27, Zack Rusin <zackr at vmware.com> wrote:

> On Saturday 10 April 2010 18:44:27 Luca Barbieri wrote:
>>> r300g: hack around issue with doom3 and 0 stride
>>>
>>> This is most likely a bug in the mesa state tracker, but do the  
>>> quick
>>> hack for now to avoid the divide by 0.
>>
>> This is not a bug: stride 0 means that the vertex attribute is
>> constant for all vertices.
>
> Right, it's how our vbo code handles cases like
> glBegin(primitive);
> glColor4f(...);
> glVertex(...);
> glVertex(...);
> glVertex(...);
> glEnd();
>
>> Thus, the patch is not likely to be correct: you should instead  
>> either
>> program stride 0 to the hardware if supported, or fetch the vertex
>> attribute with the CPU
>
> Dave, jfyi, i implemented this a long time ago in svga, just search  
> for
> zero_stride in there (svga_hw_update_zero_stride in particular), you  
> should be
> able to almost simply copy&paste that code.
>
> z
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