[Mesa-dev] [PATCH 6/7] softpipe: add dual source blending support

[Brian Paul]

On 04/09/2012 09:14 AM, Dave Airlie wrote:
> On Wed, Apr 4, 2012 at 4:16 PM, Brian Paul<brianp at vmware.com>  wrote:
>> On 04/03/2012 07:16 AM, Dave Airlie wrote:
>>>
>>> From: Dave Airlie<airlied at redhat.com>
>>>
>>> This adds support for a single dual source blending MRT to softpipe.
>>
>>
>> Why can't we do dual-source blending to all RTs?
>
> The problem is currently TGSI can't encode (location, index) color
> shader outputs,
>
> So the shader outputs would have to be mapped from a 1 dimensional
> array to something 2 dimensional,
> either defining alternate output colors as primary/secondary, or the
> secondary color as being an array after the primary color outputs.
>
> So I checked the hw, and none of it does this, they all report 1 dual
> source MRT, so I see no reason to make gallium care until someone
> creates hw that cares.

OK.  Maybe you could add this info as a comment somewhere (if it's not 
there already and I missed it).

-Brian