Current status of EGL spec

[Brian Paul]

Adam Jackson wrote:
> On Wednesday 10 August 2005 14:49, Michel Danzer wrote:
> 
>>On Wed, 2005-08-10 at 08:17 -0600, Brian Paul wrote:
>>
>>>First, OpenGL conventionally doesn't use in/out parameters like that.
>>>  Second, how common is it that hardware can't support 1-pixel
>>>positioning?  If it's not a common problem, I'd defer for a future
>>>extension which would allow you to query the positioning granularity.
>>
>>As mentioned by Jon, our current hardware can only position the CRTC
>>offset with a granularity of 8 bytes (i.e. 2-8 horizontal pixels).
>>Upcoming hardware will only support horizontal panning with a
>>granularity of four pixels (irrespective of depth).
> 
> 
> ISTR a few cards that can only change the viewport within the granularity of a 
> single framebuffer tile.  I believe savage works this way at least.
> 
> How about this: eglScreenPositionMESA snaps to the northwest if the requested 
> position isn't aligned, and add EGL_SCREEN_STEP_[XY] to eglQueryScreenMESA, 
> which return the grid intervals in pixel units.

I'd call the query EGL_SCREEN_POSITION_GRANULARITY_MESA (returning two 
values).  The granularity term comes from the queries for point size 
and line width.

If there's no objections, I could add that to the spec.

-Brian