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C | Don Hopkins

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History and Future of OLPC SimCity / Micropolis

There are several different versions of SimCity, and at least two different names (so far):

  • The original version of SimCity was developed by Maxis on the C64, and ported to various platforms, including the Macintosh. Maxis licensed the Macintosh SimCity source code to DUX software, to port to Unix.
  • DUX Software contracted me (Don Hopkins) to port SimCity to Unix, and I developed "SimCity HyperLook Edition", while working at the Turing Institute on HyperLook with Arthur van Hoff. The user interface was written in PostScript, which ran on the NeWS window system on Sun workstations, and it supported multiple zoomable views, pie menus, annotating and printing maps, and many user interface improvements.
  • After Sun canceled NeWS, DUX Software contracted me to rewrite the HyperLook user interface in TCL/Tk for X11, and I developed a multi-player networked user interface using the X11 protocol. The TCL/Tk version of SimCity has been ported to various Unix and non-Unix platforms, including SunOS, Solaris, Irix, HP/UX, OSF/1, Quarterdeck Desqview/X, NDC X Terminals, Warp, and Linux. The contract to sell SimCity for Unix expired after ten years, so the TCL/Tk version was no longer commercially available.
  • OLPC SimCity is based on the TCL/Tk version of SimCity. SimCity is a trademark of Electronic Arts. Don Hopkins adapted SimCity to the OLPC, thanks to the support of John Gilmore. OLPC SimCity will be shipped with the OLPC, and it has been run through EA's quality assurance process and reviewed for integrity. EA reserves the right to review and approve any version of the game distributed under the name SimCity.
  • "Micropolis" is the name of the current GPL open source code version of OLPC SimCity. That was the original working title of Will Wright's city simulation game. Since Micropolis is licensed under the GPL, anyone can do anything they want with it that conforms with the GPL, except they can't call it "SimCity" (and a few other limitations to protect EA's trademarks).
  • Other differently named projects can be forked from the Micropolis source code, as long as they're not called SimCity.
  • Improvements to the open source code base that merits EA's approval may be incorporated into the official "OLPC SimCity" source code, to be distributed with the OLPC under the trademarked name "OLPC SimCity", but only after it's been reviewed and approved by EA.
  • In the short term, the TCL/Tk version of Micropolis can be upgraded to support the latest version of TCL/Tk, fix bugs, improve the user interface and Sugar integration, etc. Once that is stable as well integrated into Sugar, it could be submitted to EA to become the official version of "OLPC SimCity" distributed on the XO laptop.
  • In the long term, Micropolis can be recast from C to C++ classes, so it's possible to define clean interfaces between software modules, and make multiple instances of the simulator that don't interfere with each other, as well as easily interfacing it to Python using the SWIG interface generator. That should be done in a language-neutral way, so you could plug the simulator engine into many different languages and programming systems. Then more work needs to be done to open it up, and make it re-vectorable (plug-ins, events, callbacks, hooks, aspect oriented programming, etc), so you can replace and extend the various modules with the host language(s), eventually re-implementing most if not all of SimCity in another language.

GPL Open Source Code of "OLPC SimCity" to be called "Micropolis"

The GPL source code version of SimCity will not be called "SimCity", but we will use the SimCity source code to make a city building game called "Micropolis", which was the original working title of SimCity. That's because EA reserves the right to review and QA the official version of the game that's published under the name "SimCity" on the OLPC. So we can make improvements to the TCL/Tk version of Micropolis (based on the GPL source code), and submit them to EA for review and QA, which if they approve, will be used as the officially branded version of SimCity for the OLPC. It will be the same code, but the only difference is the name, which EA understandably wants to protect, be ensuring the quality and integrity of OLPC SimCity.

The Soul of The Sims, by Will Wright

The Soul of The Sims, by Will Wright
Macintosh HD:XmotiveHarness:src/Motive.c
Tuesday, January 28, 1997 / 9:25 AM

This is the prototype for the soul of The Sims, which Will Wright wrote on January 23, 1997.

I had just started working at the Maxis Core Technology Group on "Project X" aka "Dollhouse", and Will Wright brought this code in one morning, to demonstrate his design for the motives, feedback loop and failure conditions of the simulated people. While going through old papers, I ran across this print-out that I had saved, so I scanned it and cleaned the images up, and got permission from Will to publish it.

This code is a interesting example of game design, programming and prototyping techniques. The Sims code has certainly changed a lot since Will wrote this original prototype code. For example, there is no longer any "stress" motive. And the game doesn't store motives in global variables, of course.

My hope is that this code will give you a glimpse of how Will Wright designs games, and what was going on in his head at the time!

Read The Soul of The Sims code here...

Pie Menus for X10 "uwm" Window Manager - June 1986

My second implementation of pie menus (source code), written in June of 1986, was an extension to the X10 "uwm" window manager.

I refactored "uwm" and integrated it into Mitch Bradley's Sun Forth system, to implement a Forth programmable window manager with pie menus called "pietest" (source code). I reprogramming the window manager's main loop in Forth, to perform an empirical comparison of pie menus with linear menus.

Later, I wrote this generic pie menu layout and tracking code written in C is open source, and may be used as a basis to implement pie menus on other systems. It supports pie menus with any number of items. Each item can be of any positive angular width, as long as all the item widths add up to 360 degrees. Each item records the quadrant and slope of its leading edge. A leading edge is a ray going out from the menu center in the direction given by an item's (quadrant,slope) pair. The area of a pie menu item is the wedge between its leading edge, and the leading edge of the next menu item.

The generic pie menu tracking code is optimized to minimize floating point division and avoid calling atan2 during mouse tracking. But now most computers are much faster and have floating point hardware, so the optimizations are no longer necessary to keep up with the mouse (but they still might be useful on low end computers and small embedded devices).

Theta Menu Test for X10 - June 1986

My first implementation of pie menus was written in June of 1986: a simple proof of concept called "theta menus," written in C for X10 (the window system that preceded X11).

Educational Multi Player SimCity for Linux Proposal

Back in March 2002, Maxis told me they were interested in supporting the educational use of products like SimCity. Earlier, I had developed a multi player version of SimCity, which runs on Linux/X11, and was scriptable in TCL. Educators and researchers from Columbia University, MIT, IBM, Xerox and other educational and commercial institutions were excited about gaining access to this version of SimCity, and adapting it to teach and stimulate students' interest in urban planning, computer simulation and game programming.

So I wrote this proposal and presented it to Maxis, but nothing ever became of it. But recently, Will Wright has been pushing EA to relicense SimCity under the GPL, so the OLPC project can use it. So it may eventually see the light of day!

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