alt Hacker NewsI bought and I am reading through your book as I build a sw rasterizer. On the chapter of clipping, it was not entirely clear to me how many planes you clip against and how many triangles result.
Presumably if you clip against all 6 planes, you get 3+6-2 = 7 triangles in the worst case, which is kind of annoying. However, if you're going to use the AAAB triangle raster method as described in this HN post, then it seems there's no need to clip against left/right/top/bottom planes of the frustum, since it is simpler to just clip the screen-space AABB of the triangle instead. So one just needs to clip against near/far. This is simpler and faster.
I was curious if you had given any thought on that, or if you plan on working on a second book with more details on these nuances.
My book tries to be as accessible as possible; a high schooler with little to no knowledge of linear algebra should be able to understand all of it. So in every case I've chosen simplicity (code and/or conceptually) over performance, but without sacrificing correctness. Not always an easy balancing act!
I would not recommend anyone to write a production rasterizer using the algorithms in my book. This website seems more performance-focused (Bresenham is the obvious choice to draw lines, for example).
Specifically about clipping, you can ignore all the planes except the near plane, and everything will be fine. You'll try to draw more pixels outside the canvas but that's just slow, not problematic. The near plane does protect you from divisions by zero and from points with negative Z, which project upside down and mess things up.