[cairo] Mixing Cairo & Traditional 3D:

[Jeremy Moles]

For historical reference (I'm sure other people in the future will find
this handy) I've uploaded the modified and working version of file
representing how to draw regular OpenGL and Glitz on the same frame.
(Thanks to Reveman, who is very much the man).

It's quite, quite slow--so, the best thing to do (which I'm working on
now) would be to draw to a glX Pixel Buffer instead--when necessary--and
then glDrawPixels that onto your scene instead of diving into the Cairo
API every frame. I haven't actually made this work yet, but I'm very
close (and will post that code too when it's done).

http://www.cherustone.com/cairo.cpp

On Tue, 2006-02-07 at 19:17 -0500, Jeremy Moles wrote:
> I wasn't expecting an immediate response to this or anything, so I'm
> just updating it with what I've tried so far. However, if what I'm
> trying is impossible at the moment I hope someone will tell me before I
> waste the rest of my free time after work trying to get this to go. :)
> 
> Firstly, I can successfully use glitz to setup my glX context correctly
> to work with both of my "render functions." That is: I can use the code
> I modified from cairogears to do the standard DRAWABLE->SURFACE->CONTEXT
> dance in glitz and then, in my "render loop", simply make calls to GL
> and everything works fine (lets call this function render_gl), never
> once using anything to do w/ cairo. My function just spins a triangle on
> it's X axis.
> 
> Alternatively, I can not make any calls to GL and instead use standard
> cairo functions to draw paths, etc (lets call this function
> render_cairo). This function creates a big, green X.
> 
> What I still can't do, however, is mix the too--even though, as far as I
> understand, I should be able to. I'm still very much a newcomer to
> Xlib/GL/Cairo, so I could be wrong in my assumptions about how this
> should work. I've read through the GLX PDF from SGI, and that's where
> I'm getting my information. Furthermore, my older code does a lot of
> what glitz does for me--setting up the context, making it "compatible"
> w/ X, etc. 
> 
> I've updated the link below to reflect the small progress I've made. It
> almost works--or rather, the very first frame works. It may not be a
> problem w/ glitz+cairo at all, but instead me not doing some steps
> between raw GL calls and cairo calls to make the GL "states" sane.
> 
> http://www.cherustone.com/cairo.cpp
> 
> On Mon, 2006-02-06 at 19:32 -0500, Jeremy Moles wrote:
> > I'm not sure if this question has been asked before, but my google-fu
> > was weak and I wasn't able to come up with anything.
> > 
> > I've been thinking about using Cairo (particularly, glitz) as the 2D API
> > for a small 3D engine I'm working with. I've been trying to integrate
> > glitz (using the code from cairogears) with my 3D engine, but have been
> > entirely unsuccessful, mostly in part to my non-understanding of Cairo
> > at this low level.
> > 
> > Does anyone have any code demonstrating this? Or, better, can anyone
> > write some very simple psuedocode showing how I should do it? The code
> > I'm working with is here (much of it directly from cairogears):
> > 
> > http://www.cherustone.com/cairo.cpp
> > 
> > Any help w/ this would be greatly, greatly appreciated.
> > 
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