May 2009 archives

Space Invaders

A while ago I started experimenting with Dmitry’s handy Raphaël SVG/VML library for doing some charting.

The charting work has not yet seen the light-of-day but during some spare moments I had a look at implementing an old arcade game using Raphaël. A very rough, incomplete and buggy approximation of the original Space Invaders.

Given that this is an “alpha release” of something on my blog and also that I don’t really like IE, despite Raphaël supporting IE I never tested this game in IE and hence, in that browser you probably can’t currently get beyond the intro screen because I didn’t wire up the keyboard controls. I may get it to “work” in that browser if somebody eventually guilts me into it. I probably should get it working in IE because, well, otherwise I’m partly wasting the benefits of Raphaël over pure SVG? Anyway…

It does work in Firefox, Chrome and Opera… possiby Safari, though again… untested so far.

I used Raphaël for the graphics, SoundManager2 for the sounds and implememented the top scores over on AppJet which unfortunately seems to be having occasional problems so I might have to move that to an install of couchdb I have.

Some observations

1. JavaScript in the browser is probably fast enough right now for games of this type though you would have to do some optimisation. Apart from some time shift corrections my game code got no speed optimisations. That said, setTimeout and setInterval seem fairly inadequate and difficult to work with. I didn’t use a global/world clock but that is probably going to be necessary for decent synchronisation.

2. I didn’t spend much time on polishing the game and it shows.To make a highly playable game a huge amount time is going to be tweaking the UI, playability, difficulty progression and generally getting it polished. If web developers consider the amount of effort put into the final polishing stages for a website and multiply it by… ten… they might get an idea of how much time would go into polishing something as interactive as a game like Space Invaders.

3. I used a boatload of closures and prototypal inheritence via object cloning and didn’t care about doing any memory cleanup. I don’t typically use Chrome but V8 really handled that unoptimised code really well. I would expect Tracemonkey to be as good whereas the release of FF3 I’m using seems to struggle a little.

4. Raphaël worked nicely but in order to get the two animation states for the invaders I ended up doing them as sprites and constantly changing the sprite source for all the invaders. Without spending more than thirty seconds looking at Raphaël’s internals I suspect my code would perform better to do them as actual SVG and just change the path for each state instead of constantly adding and removing sprites.

5. I don’t really think it matter but the code for this Space Invaders version is not MVC. All the objects are responsible for calling the draw and sound API’s directly based on their own state. I used what is probably more of a morphic style which seemed much more natural for what I was writing.

For the game, no guarantees given as to whether or not it will crash any browser at any time. There’s a bunch of timeouts still running when you die so try to not leave your browser sitting on the high score page for any length of time just yet.

Anyway, here it is: Space Invaders.

Be warned that it has sound, the sound is a bit crap… and you can’t (yet) disable it. Also, I’m well aware that the second level is basically impossible at the moment. I’ll look at some improvements in the coming days and weeks.

If anybody wants to see the game code, without having to view source the game itself you can see that over here.

A post on JavaScript tagged with game, raphaeljs from Friday, 22 May, 2009 with three comments.

Objects, messages, users, people

One of the highlights for me at JAOO Sydney 2009 was Dave Thomas’ talk on Cloud computing. Among other things, he talked about the vast dinosaur swamp of OO middleware that Java developers will be having fun maintaining for the next thirty years.

As somebody whose programming time is mostly either UI related in JavaScript or hobby coding in whatever takes my fancy in a given week (this week it’s factor) I was in a good position to laugh in a “it’s funny because it’s not happening to me” way at the humorous insights from Dave, the self confessed former Pied Piper of Objects. Actually, I found it especially amusing because my recollection of computer science at university in the late 90’s was that almost every student at the time was begging, demanding, wailing and gnashing their teeth… to be trained as a member of this army of average Java middleware programmers.

Of course, opting to code UI in JavaScript long ago revoked my membership to the fraternity of real programmers so my hyperbole on these things can freely be dismissed as nonsense by that part of the world shepherding business objects for a living.

I was raised on objects. I like objects. I do not like what we did with them.

In particular, I don’t like that I can sit in a meeting of non-programmers who once walked past a Computer Science 101 lecture and hear somebody saying that “we should take an object-oriented approach” to the problem.

I don’t like that anybody doing architecture ever talked in terms of UML class diagrams where all the business objects were drawn and detailed and then all the messages, you know the actual stuff going on was reduced to zero. It’s all interface, all objects and nothing happening. That’s not designing a living system for code, it’s designing a pyramid to bury people in.

All objects with no messages, no configurability, no data. Everything else got moved or obliterated until finally, finally when somebody turned around and realised “Hey, we need ways to do a bunch of this other stuff” the answer that came forth was XML. So now there’s this whole universe of people programming all the important parts of their software in XML. I don’t care to take a guess at how that is going to work out.

Of course, that was all too hard for many people and instead of following the musical pipe they went off to use PHP, broke every single principle of good, bad and ugly software design - including some that weren’t invented yet, and still managed to get things done. That said, I’ve done enough work with things such as the Wordpress template system to be reasonably confident that something has gone horribly awry and that there’s a good chance that a whole community of programmers will also be keeping themselves in jobs maintaining the mess they’ve created in PHP.

Back to JAOO though, it was good to see a strong representation for dynamic languages, DSL’s, functional programming and on top of all that, it was good to hear all types of people with a good sense of history and architects talking about service oriented architectures and composition.

Now, at this point I would assume that any lispers still paying attention to current trends can only be wondering why it took so many dances around the prickly-pear tree before more people started to “get it.” The lispers may have questions such as “Did it really take fifty years for lambda to even start entering mainstream consciousness?” and “Is XML really what you made of s-expressions?” and those would be just warm up questions… what happened?

The shift to DSL’s is encouraging… I can only hope that this time we can actually get them right as almost everything that has come before has been an abomination. That goes double for most of the 4GL’s around, I’m looking at you CSS. The problem with most 4GL’s is that they were designed to suit the problem, not the people who had to solve the problem. I think one of the big challenges going forward will be how to design languages, or design the space around which languages can develop, that work better for users… while still maintaining conceptual purity and elegance.

A post on Programming tagged with language, observations, programming from Monday, 11 May, 2009. Comment on this entry.

More or less

I seem to remember once sitting in a software project meeting where the following discussion took place…

‘What day of the month is it?’ he said, turning to Alice: he had taken his watch out of his pocket, and was looking at it uneasily, shaking it every now and then, and holding it to his ear.

Alice considered a little, and then said ‘The fourth.’

‘Two days wrong!’ sighed the Hatter. ‘I told you butter wouldn’t suit the works!’ he added looking angrily at the March Hare.

‘It was the best butter,’ the March Hare meekly replied.

‘Yes, but some crumbs must have got in as well,’ the Hatter grumbled: ‘you shouldn’t have put it in with the bread-knife.’ †

Then again, perhaps it was a dream because I can’t remember if everybody was standing up or not.

Besides… in this new hyperreality it all would have been tweets and there’d be no watch and nobody watching - just a handful of autonomous iPhones tweeting away whilst their owners slept. Roomba style.

In this new hyperreality there are nine thousand eminently usable ways to do useless things and no usable ways to do anything useful. I’m not sure whether that matters though because at some point “usable” will become heterological.

If nobody knows how to write or design software there are at least two options:

1. Stare at our navels and argue over a neologism for “poison the language.”

2. Repurpose some old software. That may be all we could do regardless because really, there are probably only five different possible software applications, just like there are only seven plots and eskimos have… what was it at last count?… nine thousand words for snow.

Going back to that first scene though. If it were, in fact, a dream then in the next sequence I begin to describe the latest poster child of this trend before quickly being interrupted by a network execubot:

Silence hack! We’ve been monitoring our Nielsen families carefully and during the 12 seconds … was on screen, viewer eyeball focus was up 90%.‡

I find it encouraging that everybody is getting better at inventing value from these things. Perhaps the web really is ready to supplant all aspects of television.

If questioned, I will claim that this post may be either the Eraserhead of posts on this blog or the Plan 9.

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† Of course, the quote is actually from Alice in Wonderland
‡ This one from Futurama Episode 5-15.

A post on Nothing tagged with agile, baudrillard, nietzsche, nonsense, twitter from Tuesday, 05 May, 2009.

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