Thor Frølich

UIPickerView with checkmark

2011-08-12T14:31:17+02:00

A client recently wanted a UIPickerView similar to the one Mobile Safari uses when selecting a dropdown menu on a webpage. It shows a checkmark when the user taps an entry and doesn't select entries when they scroll past the middle region, which is the default behavior of a vanilla UIPickerView.

This turned out to be a bit of work, so I thought I'd package up a generalized version of it and release it on Github.

iOS and Multiple Fonts of the Same Family

2011-08-10T22:23:07+02:00

I've just run into an annoying bug regarding custom embedded fonts in an iOS app. It turns out that if you're embedding multiple fonts from the same family, the compiled app will for some of the fonts use one of its siblings instead.

This answer on the invaluable Stack Overflow tells you to change the family name in each of font files to get around this issue. Here's one way of doing that:

Download and install TTX/FontTools.
Use the newly installed "ttx" command line tool to create a .ttx file from each of your fonts files.
Open these .ttx files in a text editor and use search and replace to rename all instance of only the family name. I replaced them with the name of the particular font I was modifying (eg. "MyFont" became "MyFontBold").
Use "ttx" again to convert the edited .ttx files into .otf files, ready to be added to your Xcode project.

Centering subviews in a UITableViewCell

2011-07-28T15:02:13+02:00

For a client project I recently had to add a subview to a UITableViewCell's contentView and have it centered both horizontally and vertically. This cannot be achieved by simply setting something like the following when configuring the cell in cellForRowAtIndexPath:

 myAwesomeSubView.center = cell.contentView.center;

The above will only center the subview horizontally. To achieve vertical centering however, you can instead subclass UITableViewCell and override its method for laying out subviews:

 - (void)layoutSubviews
    {
        [super layoutSubviews];
    
        for (UIView *view in self.contentView.subviews)
        {
            view.center = self.contentView.center;
        }
    }

I've had to do this a couple of times and keep forgetting how, so I thought I'd commit it to Google for posterity and anyone else who might need to do the same.

Something of a Plunge

2011-07-28T13:02:13+02:00

As of July I am no longer employed by Io Interactive. I've been with the company for 11 years and was just a young clueless lad when I started. During my tenure I've had the privilege of trying a lot of different things (graphics, game and level design and a bit of coding) on many interesting projects (the Hitman series, Freedom Fighters and Mini Ninjas). I've worked with amazingly talented people and I've learnt most of what I know professionally from them.

A couple of years ago when I discovered the joy of programming, I began entertaining the idea of starting an iOS development shop with a former colleague of mine who shares my interest in the platform. Now we have and it is called Strange Loop.

At the moment we're hard at work on our first two client projects and it's everything I'd dreamed it would be. We'll put up a section showing off our work once they hit the App Store.

Slice HD

2011-04-13T00:00:00+02:00

I just played through Slice HD and I enjoyed it immensely. It's a prime example of using the touch-based interface of the iPad to create mechanics you otherwise couldn't. In short, the game is about carefully moving sharp instruments out of the way of one or more buttons in order to press them. The game has a stark surgical steel aesthetic which fit the mechanics very well. If a knife cuts you a sharp sound is heard, blood spatters the screen and you've failed the puzzle.

Which leads me to my only gripe with the game and unfortunately it's a rather big one. Not only do you fail the puzzle at hand (haha, see what I did there?), the game boots you back to the previous level.

Wait, what?

I found that to be an extremely annoying structural decision in an otherwise mechanically superb game. Curiously, the game suddenly stopped this frustrating behaviour for me about 3/4 through the game, for which I was very grateful. Whether this was a progression-based change or if I'd simply failed enough puzzles for the game to stop punishing me, I don't know.

The game contains around 20 puzzles (I forget the exact number) and as such is fairly quick to complete. I found it to be a great immersive experience and a really good use of $2.99.

Oh dear, Jekyll

2011-04-04T00:00:00+02:00

I'm currently moving the site from Wordpress to this new-fangled Jekyll everyone is talking about. This will be horrible (more so than usual) until I manage to import the older posts and style this thing properly.

Photo Shape

2010-11-10T00:00:00+01:00

I've recently released my very first iOS app on the App Store. It's called Photo Shape and allows you to manipulate a photo from your photo library and save it back to the library when done. Technically, it's mapping the photo unto a subdivided grid and let you move control points in a bezier lattice which in turn deforms the mesh grid. Now I have to get to work on an update to get rid of some minor annoyances.

Vertex Buffer Objects on the iPhone

2010-03-19T00:00:00+01:00

I'm currently building an iPhone app in which I enable the user to manipulate the vertices of an OpenGL mesh. The first implementation simply pushed an interleaved vertex data array (containing vertices and texture coordinates) to the GPU every view update.

I had read several times on the web that vertex buffer objects (VBOs), in spite of being recommended by Apple, don't yield any performance gains over the more direct approach. Therefore I opted for not using them.

That is, until I started looking into squeezing more performance out of the app. I was seeing satisfactory framerates on my iPhone 3GS, but I wasn't entirely happy with the performance on the iPhone 3G. So I thought I'd try those fabled VBOs. My expectations were somewhat low since most of what I've read on the intertubes seemed to indicate little to no difference.

Good news and bad.

VBOs gave me a significant performance boost on the iPhone 3GS. But alas, no discernible difference on the iPhone 3G, where I needed it the most. Likely there's no proper hardware support for VBOs on the 3G. However, using VBOs in your code will still work on this phone, but with no performance gain.

So in conclusion, VBOs are totally your best friend, except when they're just some random guy who's generally pretty friendly but sometimes says inappropriate things at parties and don't know when it's time to leave. Yes.

Oh well.

Deep Blue Sea 2

2010-01-28T00:00:00+01:00

My good friend Brian Meidell has launched the website for his upcoming game "Deep Blue Sea 2". He's a very clever and talented guy, so you probably should check it out.

Dabblings in Flash

2009-12-17T00:00:00+01:00

While on paternity leave I decided to have a look at ActionScript 3.0. It has to be said that I'm uncertain of the long-term feasibility of Flash for various reasons ("oh hi, js+html5"), but I thought it'd be fun nonetheless.

I don't have Flash Pro, so I downloaded the free Flex SDK which worked ok once I figured out the build process (ie. creating a build.xml). Above is my (on-going) messing around with said SDK. It's placing black cubes (wow!) on the vertices of a generated icosahedron, (subdivided once for more points). You can rotate the whole thing by moving the mouse away from the center.

Gumowski-Mira attractor

2009-07-07T00:00:00+02:00

Oh, dear. Another attractor. I'm pretty sure the dread lord Cthulhu lives inside the Gumowski-Mira transform. Play around with it for a while and I'm sure you'll agree. Sometimes it takes quite a number of iterations before enough points have accumulated to manifest anything interesting, so be patient.

Peter de Jong attractor redux

2009-05-15T00:00:00+02:00

I've been spending a little time on my attractor applet to improve it (and improvement was indeed direly needed). Now it's possible to reparameterize by holding left mouse button and moving the mouse. That will produce a live preview. Releasing the mouse once a desired shape is arrived at will render said shape using a large number of iterations.

Antialiasing is done using a logarithmic density map to control brightness and by fuzzing coordinates a bit using random(). I've still to implement blending of single pixels hit by more than one color to reduce the current flipping during rendering.

Streaming games?

2009-03-25T00:00:00+01:00

For some time I've pondered the next paradigm in gaming. Specifically if the current developer -> publisher -> customer chain will still be relevant (no). Of course it depends on the severity of the change, but the word paradigm does imply major-ass change and we do seem to be on the cusp of something.

Then this shows up. Crazy technical hurdles notwithstanding, I will consider this a strong contender for next paradigm in video games. Streaming games as video would make game development inherently single platform, which is a bit of a dream scenario from a production standpoint. Brick-and-mortars can be tossed into the nearest volcano. Customers become hardware independent. Poverty is eliminated and we each get our own unicorn.

Particle Flow Field

2009-03-15T00:00:00+01:00

Continuing my dabbling in particles I've now created a flow field for them to move in. You know, to entertain the little critters. It's fascinating how these flow fields acting on the particles give them the appearance of having flocking behaviour, with much less computational overhead (at least for non-quad tree optimized particles). Don't look at the code. Your eyes might melt.

Particle Ink

2009-03-09T00:00:00+01:00

I've updated my aforementioned particle class, so it can now iterate through an array of attractors. Pretty simple stuff, but it can yield some interesting visuals when a few randomly placed attractors act on the particles. The code isn't pretty and it will likely run slowly on older machines due to the high number of particles. I probably should look into a more efficient way than just running every single particle against the full array of attractors.

Particles and noise

2009-02-24T00:00:00+01:00

I spent some time this weekend writing my own particle and emitter class in Processing, to learn more about the language and the arcane lore that is particles. Ultimately I'd like to do some attraction and flocking behaviour with these particles. That would reaquaint me with vector math, a field of which my previous very limited comprehension is almost gone. I really regret not paying more attention in school.

The following applet is just a simple manifestation of my messing around with adding perlin noise to the vectors of the particles. It's nothing special, but I think the "noisy order" looks interesting.

(The particle system is very bare bones. It doesn't cull individual particles, but rather clears the whole array after some time. So there's certainly room for improvements.)

Fibonacci spiral

2009-02-21T00:00:00+01:00

Here's my second Processing sketch. I think Fibonacci and similar-looking logarithmic spirals has some very aesthetically pleasing visual properties, but that is to be expected given their nature. So I decided to make one myself and learn a little about Processing in doing so. I've also made one that approximates the Golden Ratio, but they look very much alike.