[cairo] Survey of polygon rasterization techniques

Zack Rusin zack at kde.org
Tue Jul 31 01:02:22 PDT 2007


On Monday 30 July 2007 10:42:09 pm Jeff Muizelaar wrote:
> qt
>         - tessellate to trapezoids and then rasterize trapezoids

That's not really true. It's only the case for the native X11 engine where you 
really want to be using XRender and for that you need to tessellate your 
polygons. 
Rendering to QImage (or just rendering on Qt/Windows) invokes software 
rasterizer that is a mixture of freetype2/agg rasterization techniques and 
should be faster than both. 
And by default rendering in OpenGL invokes O(n) polygon rendering algorithm 
that is based on stencil clipping and when "high quality antialiasing" flag 
is set, fragment programs are used to directly anti-alias the rendering 
shapes.

z


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