Here's what I've found so far -- it's by Chris Rowett:
http://conwaylife.com/forums/viewtopic.php?f=7&t=1026
Years ago I made a cellular automata AfterEffects plug-in that let you zoom in and pan to follow gliders around. It also had a colorization feature (since the cells were 8 bits and AfterEffects deals with RGBA) that let you sample a colormap of 256 colors from another layer along a line between two animatable points (so you could easily animate natural color gradients from images and video). You could initialize and draw into the cells by overlaying or combining channels of other layers, so you could use the full power of AE to precisely control and visualize the simulation.
It wasn't particularly "interactive" (beyond tweaking control points on the timeline then running it in AfterEffect's preview mode), but you could control all the rule parameters and animate them with the timeline, and apply any AfterEffect transformations and filters to the drawing overlay input or the colorized output.
This video shows the CA AfterEffects plugin, and also the same CA code running in a couple of live interactive editing tools (including SimCity).
https://www.youtube.com/watch?v=eCVJ08gK2o8
I've rewritten the CA code in JavaScript, but the current user interface is arcane, and I would like to rewrite it in TypeScript as a module that can plug into some nice interactive playing and editing tool like LifeView.
http://donhopkins.com/home/CAM6
https://github.com/SimHacker/CAM6
It's really hard to make one user interface or visualization that works well for all rules. A cellular automata viewing and editing tool that supports different rules needs to be deeply customizable.
It turns out that each CA rule needs its own specialized user interface with rule-specific drawing tools, effects, controls and presets for visualizing, playing, painting, explaining, etc.
I wonder if anybody working on a free successor to AfterEffects that runs in a web browser?