I finally got around to hammering out a little demo to keep me warm on these cold winter nights.
The code is a bit of a mess but it was mostly a test to see if I could do it and pull off a convincing version of the classic Fire Effect so prevalent in 1990’s demos. It uses 16 bit registers and maybe a few 65816 opcodes but it should be pretty easy to port it to the IIe.
I’ve uploaded a Prodos disk image that you can download and use with an emulator or transfer. Trust me it looks way cooler running on your real GS. The disk also contain full source code. No critiquing please, but you are welcome to send in improvements or discuss it on the comp.sys.apple2.programming newsgroup.
Keys 0-9 change the number of vblanks to wait between updates. Hit “S” for ultra-cheapo sound effects if you want the fire to crackle. Any other key quits.