This is a blog post I've been meaning to write for a while now, because it's definitely surprising to learn. But here's the key points: GPUs are good at triang

This is a blog post I've been meaning to write for a while now, because it's definitely surprising to learn. But here's the key points: GPUs are good at triangles. Triangles are very simple -- three planar equations tells you if you are inside or outside the shape. 2D graphics is typically specified in overlapping curves. Determining whether a pixel should be filled or not is a lot trickier -- even determining which side of a Bezier curve you are on is a non-obvious and numerically unstable problem (nitpickers corner: I know about Citardauq and Slug's root finding approximations). Part of this is a tooling and culture problem. There's a tradition and expectation in 3D to take higher-order implicit surfaces like Catmull-Clark and "bake" them down to triangles, and part of the skillset of a 3D artist is to manage this transition. 2D has no such expectation -- the API is "curveTo" and it's required realtime. And this API is not only assumed in platforms, but also TrueType fonts, and SVG graphics. There's also some other differences -- in 3D graphics, you can be imprecise with your antialiasing because the viewport constantly shifting with perspective can mask a lot of ugliness, and typical scenes will have a lot of detail and texture. In 2D, the standard is clean silhouettes (which most post-processing AA techniques do not work well on), and stability of small shapes and details (you don't want your letters to bubble and jitter around as you scroll a page or type, like you might see from a temporal antialiasing algorithm). Ultimately, 3D scenes are constructed mostly with materials and textures -- fancy things inside the shapes, but 2D is the opposite -- very simple solid color or gradient fills on complex shapes.