[cairo] Direct rendering on current GL surface

[Christophe de Dinechin]

Hello,

With a slightly more complex variant of the patch I sent earlier, I've been able to use Cairo to draw 3D text at acceptable speed. The image below shows 685 FPS, with text being rendered in native GL coordinates, slanted. I started at around 60FPS using the "naive" recommended approach of writing into a texture and blasting that texture on screen.

https://nano.taodyne.com/ddd/cairo-gl.png.

I still have problems with the clipping. Basically, with the default clipping, everything is still clipped in (0,0,width,height), which in my case is annoying because (0,0) is the center of the screen. Where is the original clipping rectangle defined (I assume it's a device-level clipping rectangle)? I tried various things, but the most obvious candidates were wrong.


Thanks
Christophe