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alfkil's picture
Last seen: 2 years 1 month ago
Joined: 2011-05-10 22:02

The Qt X11 renderer uses trapezoids to render with XRenderCompositeTrapezoids. I am trying to use the code to render with CompositeTags, but all I get is this mishmash of triangles.

XRender defines a trapezoid as

top, bottom

...where A,B,C and D are points (x,y) and top and bottom are floats.

Now my question is this: What role does the top and bottom values play?? As far as I can see, it is enough with four points to define a trapezoid, so why are the top and bottom values needed??