I am constantly baffled by the tech that people jury-rig together to make games inside of other games. Someone made a poo-powered calculator in Cities: Skylines. Another made Pokemon Red inside Minecraft with command blocks. This wild person who goes by the username s0lly has made a ray tracing demo inside Microsoft Excel.
Ray tracing, which Nvidia is pushing with its new RTX cards, is a method of simulating the way that light interacts with objects. To avoid getting bogged down in the technicalities here, I'll let Jarred's article explain how it works (opens in new tab) further.
s0lly introduces the demo in this Reddit post (opens in new tab). "Off the back of my pseudo and 'real' 3d excel models, I've made a raytracing model in excel which I hope demonstrates the basics of raytracing for any of you that are keen to learn," they say, with a link to download the spreadsheet (opens in new tab) from GitHub. It was apparently inspired by The Ray Tracer Challenge (opens in new tab) by Jamis Buck.
Based on the Readme included on GitHub and inside the .xlsb file itself, there's pretty much only one assembly-required step needed to make the thing work. You'll need to navigate to the "Objects" tab of the workbook and select row 24. Press ctrl+C to copy it. Then select all rows from 25-14405, yes all of them, and then press ctrl+V to paste the formulas. Forewarning: your computer will not like it. Even my relatively powerful machine took around 30 seconds to process all those cells.
After that, go to the "screen" tab and press either "Animate" to let the animation run along a set track or "play" to control the movement yourself with WASD.
Running the animation on my own machine is, predictably, less interesting to look at than the sped up version shown in s0lly's YouTube video. My machine ran one "frame" of the 160x90 cell image every couple seconds. It seems that Excel isn't the most efficient way to render ray traced graphics. It's still pretty neat though!
This isn't s0lly's first wild Excel demo. They've also created a 3D engine inside Excel, which is also way over my head. I can't hardly fathom what's going on here, so I'll just watch the YouTube video again and pretend that I get it and leave the poop computers and Excel wizardry to the programmers out there.