Monthly Archives: March 2013

The particle simulator

Pretty colours!

Pretty colours!

One day a friend of mine made a sort of battle royale – you had things bouncing around and when two collided they would “battle” each other. One person, determined partly by the amount of EXP they had, would turn out victorious and continue bouncing around merrily until only one remained. The “game” was somewhat fun to watch – and the fact that the names of people he knew were included made it really interesting. After all, who wouldn’t want to see their own character win?

So I asked him what he used to make all this stuff and I learnt from him that he uses Pygame for his graphical Pythoning purposes. And today I decided to try it out myself.

This cheat sheet from the internet sure came in handy – it allowed me to do what I wanted without having to go through pages of documentation. So Pygame was easy to set up. I was off to a great start.

What did I wish to make? Something equally fun and mesmerising to gaze at, of course. I decided on a sort of particle simulator, where circles would whiz around, affected by only gravity (implemented straight from the formula). It worked beautifully for the first few seconds. But then two particles collided with each other, and flew off at a funny angle. It turns out that, if the distance between two objects is small, the force due to gravity becomes extremely large. And since my particles were allowed to overlap one another, they could theoretically even have a distance of zero!

So that got fixed with an absorbing mechanism, just like the Katamari games. So now, just like the battle royale, one giant blob would remain victorious at the end, having swallowed up all the others. But of course, that would be pretty sad and boring to watch so I let you add more particles by clicking anywhere in the window.

Naaa~ na na na na-na na na na katamari damacy!

Naaa~ na na na na-na na na na katamari damacy!

The particles would sometimes go offscreen too, so I put in an auto-zooming camera option. That tended to make the particles really small (to compensate for the zooming) though.

So how long did that all take? 3 hours! Woo!


How to make a Rhythm Heaven MAD

KON-KON...KON-KAN...KON-KON-KAN KEN-KIN-KUN. Or "donk donk" to you if you've played the English version.

KON-KON…KON-KAN…KON-KON-KAN KEN-KIN-KUN. Or “donk donk” to you if you’ve played the English version.

Rhythm Heaven – making the weirdest minigames musically addictive. Rhythm Heaven MADs – making your favourite songs musically addictive. What could possibly go wrong.

About a month ago the Wii version of Rhythm Heaven came in my mail (I was a fan of the DS version and had been hoping to get my hands on the Wii version for a while now). Soon after that I decided to make a MAD for “crossing field”, the opening theme of Sword Art Online. I’d seen a few Rhythm Heaven MADs on Nico (like these two excellent ones), and wanted to try making my own. Unfortunately, the crossing field project only went halfway – the chorus had too many offbeats and I was at a loss about which minigames to utilise.

I once contemplated making one for “Evans” from Jubeat, thinking “Rhythm Evans” would make a great video title. Dotted quaver beats killed that plan though.

So then I went onto an easier song, and that became Guilty Crown’s OP, “The Everlasting Guilty Crown”. I think the project went pretty well overall, although there are a few parts which could have been better.

So now to document my procedure so that my future self can make another one of these again.

Sound effects

Adding sound effects to the song involved a lot of fiddling around...

Adding sound effects to the song involved a lot of fiddling around…

So the first of two steps was to add sound effects to the music using Audacity, and in order to do that I had to figure out how fast the song was. Everlasting had a BPM of 172.

Once I got that down, I made a click track (the track with grey lines above) in Audacity so that I could visually see where the beats were. This made it easier to know where to add the sound effects.

Next, get the sound effects! Luckily, a kind user on Nico had already ripped out the sound effects from the remixes via audio editing (if you have the song with and without SFX, you could do that yourself with Audacity and the Invert effect, then Mix and Render). So sound effects were obtained by ripping audio off these videos using Nicosound.

Then I worked out the BPM of the remixes so I could adjust the sound effects to the speed of Everlasting using Change Tempo. For reference, Remix 10 (which is a useful resource) is BPM 166.

Now that all the tools were ready, I just added the sound effects to the song however I wanted, being mindful of how the song progresses in order to make things sound good. It was interesting, trying to analyse parts of the song in order to decide which minigame to use where.

One note though – if you’re using the rocket minigame, the Change Pitch effect is useful for making the pitch of the rocket sounds follow the song.


This was a nice exercise in learning how to use Premier and After Effects

This was a nice exercise in learning how to use Premiere and After Effects

Once you’ve got the sound effects mixed into the song, everything should sound pretty good already. But being able to see what happens makes it even more catchy!

First, obtain the video resources. Grab Rhythm Heaven perfect runs from somewhere – I just took some off Niconico.

Then just add the videos in! I make it sound easy, don’t I? But for the most part, it is. You’ll have to change some video speeds by working out the BPM of the video clip’s original songs though. Also, add some dip-to-black transitions between each clip to make the transitions smoother, and everything should be pretty much fine.

There’s a few times where things might get tricky though. One situation is if you can’t find any video clip which has the exact same beats you have, and another is if the video fits your beat, but the video itself isn’t very good (or your video cutting is obvious because, for example, a butterfly just teleported). You might have to change your beats in those situations to make things simpler, or use After Effects to alter the videos. Also, if you’re having trouble making your video be on the beat, you can add the click track into the project as audio and use it as a visual reference again.

And that’s about all there is to it. It isn’t very hard – all you need to do is add sound effects and video and if you can get your hands on both then the rest is mostly straightforward. It might take a bit of messing about, but isn’t exactly a difficult project. For the record, Everlasting took about 3 or 4 days.