Dri2 buffer format

[Russell Shaw]

On 10/11/10 09:28, Jerome Glisse wrote:
> On Mon, Nov 8, 2010 at 6:55 PM, Russell Shaw<rjshaw at netspace.net.au>  wrote:
>> On 09/11/10 04:53, Jerome Glisse wrote:
>>>
>>> On Mon, Nov 8, 2010 at 10:52 AM, Russell Shaw<rjshaw at netspace.net.au>
>>>   wrote:
>>>>
>>>> Hi,
>>>> How should the "format" of a DRI2 buffer be determined?
>>>>
>>>>
>>>> http://www.x.org/releases/current/doc/dri2proto/dri2proto.txt
>>>>
>>>> DRI2ATTACH_FORMAT { attachment: CARD32
>>>>             format:     CARD32 }
>>>>
>>>>     The DRI2ATTACH_FORMAT describes an attachment and the associated
>>>>     format.  'attachment' describes the attachment point for the buffer,
>>>>     'format' describes an opaque, device-dependent format for the buffer.
>>>>
>>>>
>>>
>>> As the spec says, it's opaque and only the driver understand it, intel,
>>> radeon, nouveau all use different things i think. DRI2 is meant to be
>>> use btw different driver of same hw which should all understand each
>>> others.
>>
>> If it's opaque, how does one know what bytes are red/green/blue so that
>> you can draw a line in the right colour?
>
> This format is intend to be exchanged btw Xorg DDX driver for a given
> hw for instance the nouveau ddx and with the mesa or other dri2 driver
> like for instance the nouveau gallium driver. Both of this component
> understand each others.
>
> DRI2 is not mean to be use by end user application, it's only use by
> Xorg to comunicate with library such as opengl that want to provide
> direct rendering to X pixmap/window.

Ok. How do i plot a pixel in Wayland? I'm not using gtk/qt/OpenGL/OpenVG etc.