EDIT 2017-11-10: The build environment instructions I've given here are quite out of date, a current one can be found here. Regarding DLL's, MinGW can link directly against them, so there should no longer ever be a need to use
gendefin anger. END-EDIT
Well I say it's like Shadertoy, but it's nowhere near as good. Either way, it's OpenGL using a texture that's generated in OpenCL, and the CPU isn't getting involved. I've also rewiggled the build system, so now it should theoretically build Windows binaries from Linux, although my Debian Wheezy tests have so far not yielded success. I'm hoping there were bugs in the gcc-4.6 version of mingw64, but there's probably a flag somewhere I'm missing, as my Windows test with the same build config on native Windows version of mingw64 with gcc 4.8 worked a treat.
So GNU/Linux users, to build this type "make". You'll need the OpenCL dev files, and some X11 stuff. It should all be in your repository. It doesn't matter if you install the Nvidia OpenCL headers, or the AMD ones, or the Intel ones. They all work the same, and all speak to each other. Your distro's package manager should have everything on hand, shouldn't be more than a couple of megabytes.
Windows users, to build this type "make". Setting it up to be that easy is a bit of a task.
dlltool -l libOpenCL.a -d OpenCL.def -k -A dlltool -l libOpenCL64.a -d OpenCL64.def -k -A
lib.afiles you need, stick them in c:\mingw64\x86_64-x64-mingw32\lib\ When the time comes that you want to use more modern OpenCL, you'll have to download the OpenCL SDK from your hardware manufacturer, find their DLL's, and run these commands on them...
gendef OpenCL.dll gendef OpenCL64.dll
.deffiles you need to give to dlltool. If you're cross compiling from GNU/Linux, dlltool is named "x86_64-w64-mingw32-dlltool". It can be coerced into producing the lib file straight from the DLL, but there's no way I'm going to distribute their DLL's.
Well, here's the link to the code. It builds on Debian Wheezy, and 64bit windows. You can build it in 32bit mode, but I've got datasets too big to fit in 4Gb of RAM. I don't support 32bit for this project. The upper case sigma, "Σ", reloads the OpenCL kernel from disk.
A note about OpenCL. If you've got current video card drivers from Nvidia or AMD then you already have all the OpenCL you need. I expect my OpenCL kernel will disagree with AMDs OpenCL compiler... feel free to fix it AMD owners :-)