[cairo] Performance OpenGL backend

Ralf mock at cipsoft.com
Wed Feb 17 03:23:48 PST 2010

Hi all,

this is my first post to this mailing list, so please be patient with me.

I am using cairo in conjunction with a 3D rendering engine called Ogre3D.
What I am doing is rendering comic panels with outlines & silhouttes.
So far I was using the image backend of cairo to make around 900 calls 
to cairo_curve_to
per frame...which seems to be a bottleneck in my application....

Since the application already deals with opengl and rendertargets (fbo), 
I thought I give
it a try with the new opengl backend of cairo.
Though I was able to integrate cairo within Ogre (where cairo actually 
uses an external created
opengl fbo) the expected performance gain is not noticeable. In fact, in 
certain situations it seems
to be slower than the image backend.

So can that actually be the case where the opengl backend is slower, 
when rendering many curves which
only fill a few pixels in the final picture or am I using the backend in 
the wrong way ?

I currently have this running under Fedora 12 linux, with the latest 
cairo version from git.

Many thanks for any hints you can provide me.


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