ElectroPortis

ElectroPortis is a Windows version of ElectroPaint, the only screensaver. This is the real deal. It is not a clone, nor a reimplementation, nor a product of manual reverse engineering. It was made by running the original binary through a custom MIPS to C decompiler.

Some new features have been added. Press "n" to create a cloned ElectroPaint window. Press "f" to toggle between the following modes:

Single full-screen: ElectroPaint will run full-screened on the monitor where the master window resided. Other windows will be closed.
Spanned full-screen: ElectroPaint will run across all connected monitors.
Cloned full-screen: ElectroPaint will run a synchronized copy across all connected monitors.

If you want a unique copy of ElectroPaint on multiple monitors, simply launch another instance and single full-screen each one.

To use ElectroPortis as a Windows screensaver, build it, rename ElectroPortis.exe to ElectroPortis.scr, right click it, and select "Install".

History of ElectroPaint

There is a a mini-history of ElectroPaint on the Web.

Many clones and versions inspired by the original have been made.

Your author also stumbled across a new development in the ElectroPaint saga. (The decompiled version presented by ElectroPortis is in fact the OpenGL version referred to in the README of this repository.)

A very old version of the IRIS GL-era ElectroPaint, containing the interactive features but lacking the script that made ElectroPaint so famous (and possibly using a different version of the animation code), is available as part of the IGL distribution.

Notes for nerds

      __    __
     /..\ /| |'-.
    .\_O/ || |   |   OH WOW
 _ /  `._ \|_|_.-'  FREE SOFTWARE
| /  \__.`=._) (_
|/ ._/  |"""""""""|  LET ME IN
|'.  `\ |         |   ON THIS
;"""/ / |         |
 ) /_/| |.-------.|
'  `-`' "         "

Building

You will need Visual C++ 2013. gcc is untested, but will probably work if you roll your own build system. clang should also work once it can fully parse the Windows API headers.

Changes made to the decompiled source

"static" was added to symbols that didn't need external linkage.
Relevant initialization routines from ep's "main" were placed in "init_ep".
The "reshape" routine was rewritten by hand from MIPS disassembly to C. (This was done while attempting an alternative method of adding the cloned mode; the decompiled routine worked fine.)
Memory returned by malloc is zeroed. Crashes occur otherwise--perhaps IRIX's malloc zeroes its memory.
GL draw calls are wrapped in order to support the cloned mode.

(Lack of) ports

Windows

ElectroPortis should run without issue on Windows XP and newer.

Linux

Most Linux users are probably on 64-bit systems at this point, and the original ElectroPaint binary is 32-bit (even on 64-bit IRIX systems, much of the IRIX base system was built as N32). Since the decompiler has no way of determining that a given piece of data is a pointer, the emitted source has a restriction: if the target ABI doesn't have 32-bit pointers (as N32 does), the code will compile, but immediately crash upon the first pointer dereference. This makes a port of any sort infeasible unless you wish to rewrite ep.c.

OS X

Same issue as Linux--even though OS X still supports 32-bit binaries as of 10.9, support for them will likely be disappearing in a future version of OS X. Furthermore, the overengineered OS X screensaver framework loads Mach-O bundles; it does not simply run a binary. The screensaver framework is, like the rest of the system, 64-bit, so screensaver mode is impossible on OS X (unless you rewrite ep.c).

Excuses

The maintenance cost of distributing a second or third version is just too high. Separate OS-specific glue is needed (GLFW is unsuitable for the screensaver mode) and different build systems would be required (there is no good platform-independent build system, don't kid yourself). That said, it took about an hour to make a simple port to both platforms supporting single window and single full-screen modes, so if you wish to make one, do so and it will be linked to here!

About the code

Part of the reason for adding multiple window/display support was a desire to provide an example of an OpenGL app that made use of multiple threads and GL contexts. There isn't much information available about the "right" way to do this; it took a while to find the issues preventing it from working smoothly. Be warned: multiple contexts within one process is a corner case that tends to expose GL driver bugs. Using a single thread and GL context to do all rendering may be the easier option in many cases, or if your needs are more demanding than recording GL draw calls and playing them back in parallel, try something like Equalizer.

The "SHRW2" rwlock used in ElectroPortis is quite nice; it generally has better performance characteristics than SRWLOCKs and also works on Windows XP.

neko68k/electroportis