Re: [Mesa3d-dev] gallium "raw" interfaces

[Chia-I Wu <ol...@gm...>]

On Mon, Mar 29, 2010 at 1:51 AM, Keith Whitwell
<kei...@go...> wrote:
> I've just pushed a variation on a theme a couple of people have
> explored in the past, ie. an interface to gallium without an
> intervening state-tracker.
> The purpose of this is for writing minimal test programs to exercise
> new gallium drivers in isolation from the rest of the codebase.
> In fact it doesn't really make sense to say "without a state tracker",
> unless you don't mind creating test programs which are specific to the
> windowing system you're currently working with.  Some similar work has
> avoided window-system issues altogether by dumping bitmaps to files,
> or using eg. python to abstract over window systems.
> This approach is a little different - I've defined a super-minimal api
> for creating/destroying windows, currently calling this "graw", and we
> have a tiny little co-state-tracker that each implementation provides.
>  This is similar to the glut approach of abstracting over window
> systems, though much less complete.
> It currently consists of three calls:
>   struct pipe_screen *graw_init( void );
>   void *graw_create_window(...);
>   void graw_destroy_window( void *handle );
> which are sufficient to build simple demos on top of.  A future
> enhancement would be to add a glut-style input handling facility.
> Right now there's a single demo, "clear.c" which displays an ugly
> purple box.  Builds so far only with scons, using winsys=graw-xlib.
I happened to be playing with the idea yesterday.  My take is to define an EGL
extension, EGL_MESA_gallium.  The extension defines Gallium as a rendering API
of EGL.  The downside of this approach is that it depends on st/egl.  The
upside is that, it will work on whatever platform st/egl supports.

I've cleaned up my work a little bit.  You can find it in the attachments.
There is a port of "clear" raw demo to use EGL_MESA_gallium.  The demo supports
window resizing, and is accelerated if a hardware EGL driver is used.

The demo renders into a X11 window.  It is worth noting that, when there is no
need to render into an EGLSurface, eglCreateWindowSurface or eglMakeCurrent is
not required.  To interface with X11, I've also borrowed some code from OpenVG
demos and renamed it to EGLUT.

-- 
ol...@Lu...