A differential compiler for computer animation

A program for the real-time display of computer animation on a bit-mapped raster display is presented. The differential compiler performs temporal domain image data compression using frame replenishment coding on successive frames of animation stored in memory as bitmaps and saves only the differences. A small run-time interpreter then retrieves and displays the differences in real-time to create the animated effect. This results in a significant reduction in storage requirements, and allows animation on general purpose computers which would otherwise be too slow or have insufficient memory. Frame creation is both device and method independent. An animation environment supports interactive editing capabilities, reconstructing any arbitrary desired frame for later modification. Frames can be added, modified, or deleted, and the animated sequence can be viewed at any point during the session. The compiler is automatically called as needed; its operation is transparent to the user. The compiler is described in detail, both in terms of data compression and the requirements of interactive animation editing.