In 1965 the University of Utah hired back a physics PhD, David Evans, to start a computer science department. Almost every pixel you have ever seen in a 3D film traces to that decision. Evans recruited Ivan Sutherland in 1968, on the condition they start a hardware company together. ARPA funding followed and Utah became the centre of gravity for computer graphics. One student in that lab was Ed Catmull. Catmull’s 1974 thesis, “A Subdivision Algorithm for Computer Display of Curved Surfaces,” is arguably the most consequential document in animation history. It solved two problems that had nothing obvious to do with cartoons. The first was visibility. Project 3D geometry onto a 2D screen and surfaces overlap, so the machine must decide what hides what. Existing methods sorted the whole scene geometrically before drawing: expensive, and broken by interpenetrating shapes. Catmull’s answer was the Z-buffer: • Allocate a second buffer holding a depth value per pixel • Initialise every de...