[Mesa-dev] vertex array regression
brianp at vmware.com
Tue Dec 20 16:57:09 PST 2011
On 12/19/2011 01:12 PM, Mathias Fröhlich wrote:
> On Monday, December 19, 2011 17:01:07 you wrote:
>> I still don't get what the purpose of the special mapping of the last
>> four/five elements is all about. Can you explain that?
> As far as I can see the last ones should not map to anything.
> The map is used only in fixed function mode. And there these arrays should not
> show up as inputs to any fixed function shader. I think that the purpose of the
> previous mapping was just to fill in anything. The changes I did serve exactly
> this purpose.
> But I agree that here should not be any mapping of these attributes in this
> mode. Attached is a small change that is probably a more clean solution to
> this mapping problem.
> The change passes a quick r600g piglit test.
>> Yeah, I see how the incorrect varying_inputs values was causing
>> _NEW_ARRAY to get set, thus hiding the problem. The solution looks
>> correct, but I'm a little worried about performance, as is mentioned
>> in the comment.
>> Marek, made that change back in March. Maybe he can take a look at
>> this too.
> I cannot comment on this, since I do not see a performance regression on my
> use cases.
I dug a bit deeper into this. When the isosurface corruption is
visible it's basically because the glVertex and glNormal values are
With glBegin/End we're sending interleaved (normal3f, vertex3f)
values. But with glDrawArrays we're sending interleaved (vertex3f,
normal3f) values. If we don't signal _NEW_ARRAY when switching from
one method to the other, the state tracker is skipping array
validation and we're drawing with normals and positions transposed.
The glBegin/End code is building vertex arrays but never directly sets
_NEW_ARRAY as a side-effect.
I've implemented a solution to this that simply sets _NEW_ARRAY
whenever we transition between glBegin/End and glDrawArrays drawing.
This fixes the isosurf bug and removes all occurances of NewState |=
_NEW_ARRAY in the recalculate_input_bindings() function to avoid a
I think this fixes the regression while preserving Marek's performance
I'll post a patch.
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