This is the "fire" SDL demo from the SDL website, updated to include resizable window support and stripped of its old build scripts.
There was never a license attached to original demo, which means that it's technically "all rights reserved", but I don't think David would disapprove. Maybe I'll ask him at some point...
Fire demo by David Ashley.
dash@xdr.com
http://www.xdr.com/dash
See the start of the fire.c program for more details.