I recently had a baby. From what I understand, it’s similar to having a dog (which I’ve never had). Taking care of a baby basically consists of doing three things:

• feed the baby
• burp the baby
• change the diaper

Unfortunately, the baby’s only form of communication is to cry. So if you’ve got a crying baby, you just have to cycle through those three things to try to figure out what’s going on. But sometimes doing the simple things doesn’t seem to work, in which case I’ve had some success with a few other techniques:

• finger switcheroo — sometimes babies don’t take bottles even when they’re hungry, like they’re too excited to drink properly, but they’ll calm down if you offer a finger knuckle to suck on
• tummy time — putting babies on their tummies makes them squirm around and sometimes that releases more gas … or poop
• shower time — for some reason, Baby Mach 2 really digs warm showers … no matter how upset he is, that always calms him down; so if your baby is crying inconsolably, give that a shot

I recently started creating another iPhone / iPad app. From what I understand, it’s similar to running your own business (which I’ve never done). Making an app basically consists of doing three things:

• coming up with the idea
• developing the app
• marketing the app

Coming up with the idea is by far the easiest part. I mean, I’ve got three apps that I want to work on right now, but other stuff keeps on coming up. Developing the app is hard, but it helps if you’re technical because there seem to be way more artists out there than programmers. The main thing is to keep at it. Try to work on your app at least a little every day, even if it’s on a piece of paper doodling ideas and user interfaces.

As for marketing … that’s a whole other thing. The main principle thing to keep in mind is that your marketing budget should be proportional to your development budget. If you’re doing a small app, it doesn’t make much sense in spending a huge amount to market it. For example, Google Ads? Just getting someone to click on the ad could cost upwards of $5 and there’s no guarantee that they’d buy the app. And I’ve heard from friends that print ads, even in iPhone specific magazines, don’t make a dent in sales. For small apps, your best bet is to give out free promo codes to reviewers and hope that one of them reviews it on their website. In addition, you should always have some way for people to see what your app is about, either with a demo video or a lite version of an app.

I recently picked up “We Rule“, a simulation game for the iPhone / iPad. From what I understand, it’s similar to Farmville (which I haven’t played). The game basically consists of doing three things:

• grow crops
• build buildings
• place them in an aesthetically pleasing manner

My kingdom’s layout is sort of inspired by where I work. There are a couple rows of trees in front of rose bushes, just like at work. There’s a river where the parking lot sometimes floods during heavy rains. There’s a little bakery that’s under construction…

The brilliant (or insidious) part of this game is that it’s got a built-in addiction cycle. You plant the crops and then stop playing. But you have to come back and play to harvest them or your crops die. You could plant crops that take longer to grow, but they’re not worth as many points and then you’ll have to wait longer to see the new stuff. And the more friends you get hooked on heroin get to join, the more money and experience points your buildings make.

Anyways, I’m not an expert by any means, but I have been playing a lot of it these last couple days and thought I’d share some tips:

• The iPad version is a little flakey with the friends list, but if you log into the iPhone version it will sync the friends list.
• Cheaper crops and buildings generally give you the best income per hour, but they also require you to play more frequently. There are even spreadsheets on this stuff.
• Use Twitter to make “friends”.

What if you’re like me and only know a couple people who play? You could use the in-game option to send out a Twitter message to all your followers. But really, how many of them are going to be playing this game? So that’s not very effective. But what if we reverse the polarity?! (Okay, that doesn’t really make much sense, but I always wanted to use that phrase.) Anyways, instead of trying to tell everyone else to play, go the other way. Do a Twitter search for “we rule iphone” and you’ll find a ton of statuses like this:

MachWerx Let’s play We Rule on the iPhone! My gamername is ‘MachWerx’. http://bit.ly/d4seUk

And bam! You’ve instantly got a list of hundreds of people who will be happy to be your friend in the game.

Last time, I posted a starfield video which demonstrates an iPad being used to look around in a virtual 3D environment. So how is this done? The basic idea is to line up the xyz coordinate system of the iPad to the xyz coordinate system of the world. Well, the world doesn’t really have an xyz coordinate system, but we’ll call “z” the direction that lines up with gravity and “y” the direction that lines up with North.

The first step, as you might guess, is to use the iPad’s accelerometer and compass to find out what direction gravity and north are in. Then, it’s a matter of taking those to vectors and rotating everything so that the iPad’s z-direction (which is initially pointing perpendicular to the screen towards you) to line up with the gravity vector and the iPad’s y-direction (which is initially pointing to screen right) to line up with the north vector. Here are the steps involved:

• rotate z so that the iPad’s new xz-plane lines up with the gravity vector
• rotate y so that the iPad’s new z-direction lines up with gravity
• recalculate the north vector in this new coordinate system
• rotate z again so that the iPad’s new y-direction now points north

But how do you know how much to rotate by? Well, that’s where trigonometry comes in. Let’s call your gravity vector . If that happens to be <0, 0, -1>, that means your iPad is lying flat on a table or something and you wouldn’t have to do anything. But for anything else, you’ll want to line up your new xz-plane with this . In other words, you need to figure out the angle between and <1, 0>. You do this by taking the arctangent of Gy over Gx, or “atan2(Gy, Gx)”.

The rest is left as an exercise for the reader…

On Monday, I mentioned that it’s possible to use the compass and accelerometer on the iPad to create a virtual world display. This video illustrates what I was talking about:

http://www.youtube.com/v/Ci4LD5ngCdc

Actually, you don’t need an iPad to do this. You could do this with any device that has a compass and accelerometer. In fact, there are several apps that do something like this for the iPhone 3GS. But I don’t have one of those, so this was my first chance to try it out for myself. Also, the starfield looks pretty awesome on a big display. On Friday, I’ll go over some of the math used to do this effect.

I recently discovered that my iPad has a compass, which was a bit of a surprise since I thought it would be like the iPhone where only the 3G version had it and I only got the wi-fi one. So now I’ve got a device that can tell which direction gravity pulls in (with the accelerometer) and can point to magnetic north (with the compass).

Neither sensor is terribly accurate but with a bit of filtering, I can get two reasonable vectors. And with two vectors, I can create a coordinate system. And with that, I can create a crude virtual world display. I’ll post a video next time showing what I mean…

With his ear-piercing cries, razor-sharp fingernails, and poison-gas cloud flatulence, my baby is the perfect killing machine. But then I watch him fall asleep on my chest after a particularly vigorous feeding and I think, “Aww … he’s just so cute…”

That’s when he’s going to strike, when I least expect it.

My first app, Mach Dice, was reviewed on iPhoner.it, an Italian iPhone site. I can’t actually read Italian, but from the Google translate version, it sounds like they liked it.

If you’ve got an iPad, check out Air Hockey Gold. It’s air hockey, on an iPad. What could be simpler? And it’s free! Also, for a limited time, it’s got an ad for my game Castle Tiles.

I happen to know the guy who made Air Hockey and in his free version for the iPad, he wanted to run some ads. But the major ad providers like Google AdSense didn’t have iPad versions of their SDK available at launch. So he just put up his own ads for friends’ apps, including mine. My ad will go away once he gets the more “official” ads working but in the meantime, it’s free publicity!

Hey, did you buy my iPhone game Boom Dice a while back? Guess what! I finally finished the update. I know, I know, it took a while. But things have been busy at work, we were in India for a few months, we had a baby, the whole iPad thing… But through it all, I’ve been working a little bit here and a little bit there on version 2.0 for Boom Dice. (Also, I wanted to wait until I actually got an iPad to make sure it worked on it.)

So what’s in the new update? Well, a picture is a worth a thousand words so a video composed of lots of pictures and sound must be worth … a bunch more? Anyways, check it out and buy it on iTunes!

http://www.youtube.com/v/Uqe6tKyA_wI