Re: [Dri-devel] basic question about glx

[Ian R. <id...@us...>]

Jacek Pop=B3awski wrote:
> I am trying to understand DRI source, now from start, i.e. from OpenGL =
calls.
>=20
> I was analizing file: lib/GL/glx/g_render.c, if I understand correctly =
there is
> stream build there, but where it's readed?
>=20
> For example in glColor3f there is identifier: X_GLrop_Color3fv. I grep =
whole
> DRI source and can't find where it's used. So how stream decoder knows =
which
> opcode is it?
>=20
> I was browsing documentation on dri.sf.net, but I am unable to find ans=
wer for
> my question:=20
> "which functions in hardware driver (like lib/GL/mesa/src/drv/r200) are=
 called
> for given GL call?".

There are a couple levels of indirection that you're not seeing here.=20
There is a set of "stub" functions for each GL call that redirect to=20
either direct rendering functions (supplied by the DRI driver) or the=20
indirect rendering functions (what you see in lib/GL/glx).

In the case of the direct rendering functions, the actual function that=20
gets called by the stub can be changed at virtually any time depending=20
on the GL state.

For the indirect functions, the opcode processing is done by the X=20
server.  That's what makes them indirect. :)  Look in=20
programs/Xserver/GL/glx to see how that is done.  Notice that there is=20
two versions of everything.  This is to handle the case where the X=20
server and the client have a different byte-ordering (i.e., the X server=20
is on x86 and the client is on PowerPC).