Bresenham's line algorithm is a way of drawing straight lines using only fast integer operations (addition, subtraction, and multiplication by 2). However, it generates aliased lines. Is there a similarly fast way to draw antialiased lines?
Is there a similarly fast way to draw antialiased lines?
No, because by definition an anti-aliased line touches more pixels. Such algorithms will be slower.
In a software rasterizer, the ubiquitous way to draw anti-aliased lines is Xiaolin Wu's line algorithm. It's not hard to implement, and anyway there's unusually high-quality pseudocode at that link.
In a hardware raster pipe, the line primitive is expanded to a screen-space quad by the default (or user-provided) geometry shader, and then drawn as two triangles, which can then be anti-aliased in the usual ways.
In a raytracer, there are a variety of options. It's worth thinking about how you actually want to draw a 1D object. Maybe as a cylinder (woo shadows!). Note that this introduces issues of perspective/foreshortening which may (or may not) be what you want. There isn't a clear generalization. Then, obviously, whatever you do, you just supersample it.