Current status of EGL spec

[Adam Jackson]

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.

- ajax
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