Video Tape Transcript of Toronto Usenix Symposium Keynote Address

This is a transcript of a video taped keynote address in absentia, for the Toronto Usenix Symposium. The normal text is Don Hopkins talking. The (parenthetcal italic text) is extra annotation and explanation that's not on the video tape.


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Hello, my name is Don Hopkins, and I ported SimCity to Unix on top of X11 using the TCL/Tk toolkit, and also on top of the NeWS window system using HyperLook. Unfortunately I can't be in Toronto to demonstrate this stuff to you, but fortunately I have some video tapes that you can see that demonstrate the whole system.



The X11 version of SimCity is multi player, and several people can join the game, and cooperate, and people draw roads, and put down buildings in different places, and then when you do something important, like change the tax rate, or build an airport, you have to get everybody else who's playing to agree where to put it, and which thing to put down. So it makes you slow down and rationalize what you're doing, and explain to people why it is you want to put it there. It's a really interesting addition to SimCity because it adds politics.



I'm going to show first the X11 version, which is on top of TCL/Tk, and that's a free toolkit that's available, written by John Ousterhaut at Berkeley. There's a book that's coming out describing it, and you can just get TCL/Tk and use it to make products for free. You don't have to pay anything for it, and it's actually very good code. It really beats the pants off of Motif, and we were able to modify it in order to support things like colormaps and multiple displays the way we needed to, and add things to it like a sound server to make sound effects, and pie menus for quickly selecting city editing tools. TCL/Tk made alot of sense for SimCity.



The first port of SimCity that I did to Unix is on HyperLook, which is an interactive graphical environment based on NeWS. We took the source code to SimCity for the Mac, and I threw away all the user interface code written in C, and just took the core simulator, and then rewrote the user interface using HyperLook, which is this direct manipulation graphical environment, kind of like HyperCard, where you can take pictures and paste them in to define the look, and then every object has a script on it that in HyperLook, the script is PostScript, which defines its behavior.



So you just create a user interface by drawing it, and then hook it up to the application, and that user interface is separated from the application, and they send messages back and forth. Now this separation of the user interface from the application is really important, and that made it much easier later to port SimCity to X11.

HyperLook has this scripting language in it, and TCL/Tk has the TCL scripting language in it, so I was able to translate the things I had written in PostScript into TCL, and have a very similar structure. It makes it much easier to develop a thing as complex as SimCity if you have an interpretive programming language there, so you can just fiddle around, and paste new function definitions into the running system.

There are some user interface editors that have been developed for TCL/Tk, but I just wrote code by hand because I was doing some more specialized things, like multiple views and putting up views on different X11 displays over the net, that the user interface editors didn't support. HyperLook has a built in user interface editor, and I'll demonstrate HyperLook SimCity and the HyperLook environment in the following video tape.



The X11 version of SimCity supports multi player, so you can add several people to the same game, and it connects up like an octopus, several X11 displays connected to one X11 client. You can cooperate on these important decisions like setting taxes and building airports. Everybody's participating in the same game and lives with the consequences of each others actions, so now you have politics in the game. There are some tools for communicating and drawing on the map, and seeing what other people are doing.



Unix was very good for porting SimCity because it's a very good programming environment. It's very difficult and lacking in multimedia things like the sound, and just doing animation easily.

I had to create alot of things that didn't exist before, that other people are independantly working on creating too. That stuff is slowly fading into view, like for example there's the NetAudio server now that lets two programs make sounds at once, it just mixes them together.

SimCity wants to go "Roar!", "Roar!", "Kaboom!", and my email program wants to go "dinga linga linga ling" at the same time, so you have to have one program handling the sound that mixes them.



One of the things I developed for TCL/Tk and for HyperLook was this sound mixer server. And then we got an NCD X-Terminal, and just layered my sound mixer on top of their sound server. It can either use the built-in audio device and be a TCL sound server, or it can use the sound server that's in your X-Terminal or your Sun or SGI or whatever, if you're running NetAudio.

There are some other hard problems to solve like the bitmap animation. X has some extensions like shared memory, that make it easy to animate, but you can't depend on it, and some peoples servers don't have quite the whole shared memory extension. It's just a pretty frightening prospect just trying to write pixels onto the screen. You have to deal with about 50 different possible combinations of different display devices, and different ways of getting to that display device.

It's very difficult programming this stuff under X. It was alot more fun doing it in NeWS. We had to give up alot of the neat graphical features for the X version that we had in the NeWS version, like scaling and zooming around. You just can't do that in X. Unfortunately, NeWS is dead. There's no longer any support for it. The thing that was really wrong with it was that it was not cross platform. You were just stuck on Suns.





The good news though is that there are much better systems, I'm working on one right now at Kaleida called ScriptX, that are cross platform. Their whole purpose in life is to provide you a really nice high level abstraction, that lets you ignore which operating system you're running on, so instead of developing for Unix, or for MS-DOS, or for the Mac, you would develop for ScriptX, and that would get you to Unix, and the Mac, and MS-DOS. More interestingly, that would get you to things that don't exist yet, that are just coming into existance, things like set top boxes with really hot graphics, and nicer systems than you're currently even dreaming about.



What we need are high level multimedia abstractions; the X graphics model is very low level, and just doesn't work, but the NeWS PostScript graphics model is really nice, but we want the best of both worlds: a high level system that runs fast on lots of platforms. Once we have a truely object oriented system, things start plugging and playing like Legos, as this video tape of the HyperLook system will demonstrate.

The good news is that in the future, we will have systems like this that plug and play with each other over the network, and it won't matter what kind of hardware you're using. And that'll be in the hands of consumers too, it won't be just for Unix weenies.

I will show you a video tape of a talk that I gave at Interval, about "Self Revealing Gestural Interfaces", which is computer jargon for "pie menus". That is a thing that I put into both version of SimCity that lets you select editing tools really quickly.





One of the nice things about running on a fast platform, is that SimCity runs really fast, and now it's a question of keeping up with the simulator. You need a streamlined user interface in order to keep up with this city that's zooming years into the future at you sit. That's what the pie menus are for, and I'll demonstrate that.



For the pie menus and the multi player interaction stuff, like putting up windows on different screens and letting people have a shared view of this one environment, it was really nice to have the source code to the TCL/Tk toolkit, in order to support that kind of stuff.

It wouldn't have been possible to port SimCity to X11 using Open Software Foundation's Motif toolkit. It just absolutely sucks. It's not open, and you have to pay for the source code, and it's not being maintained.

But there's a really wonderful community that's grown around TCL/Tk, and people are allowed to use it in their products for free, and get the source code. I implemented pie menus with TCL/Tk for SimCity, and out of gratitude, I put the source code for the pie menu module out for other people to use, just to help to community. It's a nice positive feedback situation, as opposed to the cold war situation you have with COSE, Motif, and Open Software Foundation.

We bundled the HyperLook runtime system with the NeWS version of SimCity. If you're running OpenWindows 3.0, you can get it and try it out.



We have been distributing SimCity over the Internet, and (less successfully) on CDROMs. That's possible because Unix systems have serial numbers, so we can node lock SimCity, and you can run the program for five minutes if you don't have a license, and then it melts, so you get the whole feel of the whole full blown product, and if you like it, then you call up DUX Software's 800 number, give them your credit card number, tell them your serial number, and they tell you a password to type in that will unlock it for your particular machine, then you're up and playing SimCity. No physical transaction has taken place. You're encouraged to get a copy of it over the net, and give it to your friends.

This is the best way to distribute software. Whenever we make updates, we can just put them right online, and people can just grab a new copy. I think that's the future of software distribution. I don't like the little boxes with plastic insets and little pieces of cardboard folded up to make then seem heavier and thicker. The instant gratification of distributing it over the net is really great.

Well, anyway, here's the talk, and the video tapes.



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