Where are the draw calls of the OpenGL backend? #194

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1. PucklaJ commented on Feb 10, 2026

   

   PucklaJ

   on Feb 10, 2026

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   raster.Span

   // A Span is a horizontal segment of pixels with constant alpha. X0 is an
   // inclusive bound and X1 is exclusive, the same as for slices. A fully opaque
   // Span has Alpha == 0xffff.
   type Span struct {
   	Y, X0, X1 int
   	Alpha     uint32
   }

   I did some research and found out that the draw2dgl.Painter is rendering raster.Span elements. If I understand correctly, a CPU rasterizer first creates horizontal lines out of filled geometry and then those lines are rendered using a line renderer in OpenGL. This seems to be very inefficient, since OpenGL can rasterize geometry on the GPU. Maybe I will use draw2d only for text rendering and create my own shape renderer. But at least this answers my question.

   I will keep this issue open, in case someone wants to comment on this. Feel free to close it.
2. llgcode commented on Feb 11, 2026

   

   llgcode

   on Feb 11, 2026

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   Hi @PucklaJ,
   Yes the gl renderer is not efficient at all it needs to be rewritten. It was an experimentation.
3. llgcode

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   llgcode

   on Feb 11, 2026