As I said, it's bad as a tutorial: It enforces the stupid idea, that you rasterize 2D triangles for a 3D renderer. People, who think this way are then complete

As I said, it's bad as a tutorial: It enforces the stupid idea, that you rasterize 2D triangles for a 3D renderer. People, who think this way are then completely shocked and mystified as to why there is perspective distortion to the surface attributes. And then, on 2D triangles, it enforces a bizarre notion that a triangle is not flat, so the surface attributes gradients can change from scanline to scanline.