[Mesa-dev] [PATCH 3/5] mesa: Handle clip control in meta operations.

Brian Paul brianp at vmware.com
Thu Oct 30 07:56:15 PDT 2014

On 10/29/2014 11:13 PM, Mathias Fröhlich wrote:
> Hi Neil,
> On Tuesday, October 28, 2014 18:22:33 Neil Roberts wrote:
>> On inspection it looks like this would potentially break
>> _mesa_meta_Clear when it is using GLSL because that does not save the
>> I wonder if MESA_META_TRANSFORM is not the right state flag for this
>> because all of the other state in it is about fixed-function stuff which
>> is irrelevant for shaders. It would be a shame for shader-based meta ops
>> to suddenly have to save all of that state too. Maybe it would make more
> That moved to MESA_META_TRANSFORM due to a review request. As I
> understood the rationale, it's already connected to the gl_context::Transform
> variable by the GL spec, so it belongs into transform also for meta operations.
> Brian, or what was there an other reason for moving this to MESA_META_TRANSFORM?

We've always put GL state into the attribute group specified by the GL 
specification.  Putting the new clip control state anywhere but in the 
gl_context::Transform group would be inconsistent.


> Initially I had that saved if either MESA_META_VIEWPORT or
> MESA_META_DEPTH_TEST is requested since the origin argument affects
> the viewport transform and the depth mode affects the mapping of depth
> values into the depth buffer.
> I have at that time also thought about introducing a completely new
> MESA_META_CLIP_CONTROL since clip control does not exactly fit anywhere.
> Or as a third alternative split out a _mesa_clip_control_origin(origin)
> and a _mesa_clip_control_mode(mode) from _mesa_ClipControl(mode, origin)
> and use the mesa internal functions in meta.c to save if either
> Greetings
> Mathias

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