Re: [Dri-devel] r200 / radeon blend trouble

[Keith W. <ke...@tu...>]

Roland Scheidegger wrote:
> Keith Whitwell wrote:
> 
>>
>>>> Am I missing something -- isn't this setting the appropriate blend 
>>>> modes?  Is the constant color not getting updated correctly?
>>>
>>>
>>>
>>> Yes, exactly, the constant color isn't updated at all (so the color
>>>  is _really_ constant ;-)). Mesa would call ctx->Driver.BlendColor to 
>>> inform the driver of the changed color, but neither R200 nor Radeon 
>>> implement it.
>>>
>>
>> Wow.
>>
>> OK, the r200 register is RB3D_BLENDCOLOR: 0x3218, it holds an ARGB8888 
>> color.
> 
> ok, I'll try to implement it. This register is just before the
> ABLENDCNTL and CBLENDCNTL, so that makes it easier to support these (for
> the GL_EXT_blend_xx_separate extensions) at the same time. Unfortunately
> requires a drm change, and unfortunately though I think it needs a new
> state atom (since appending to the ctx atom won't work, as it wouldn't
> be compatible at all to old drm modules). It's a pity that appending to
> the ctx atom won't work, as this would have avoided some strange problem
> (ABLENDCNTL and CBLENDCNTL are not sompletely separate registers from
> BLENDCNTL, i.e. writing to BLENDCNTL will affect either ABLENDCNTL or
> CBLENDCNTL or both, not sure yet since I still lack a test application.
> That's a problem since the ctx atom gets emitted a lot, and thus the
> previous updates to ABLENDCNTL and CBLENDCNTL in a different state atom
> get always overwritten. Maybe I'll figure out how the registers
> interact to avoid just always resubmitting ABLENDCNTL and 
> CBLENDCNTL...).   For only the blend_color extension this isn't a 
> problem though.

You could create two new state atoms and just leave the old ctx atom for legacy.

Keith