Thor Frølich

Vertex Buffer Objects on the iPhone

Thor Frølich — Fri, 19 Mar 2010 21:54:30 +0000

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

Thor Frølich — Thu, 28 Jan 2010 18:16:19 +0000

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

Thor Frølich — Thu, 17 Dec 2009 12:21:33 +0000

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

Thor Frølich — Tue, 07 Jul 2009 08:44:34 +0000

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.

Click image to start the applet

Peter de Jong attractor redux

Thor Frølich — Fri, 15 May 2009 11:24:30 +0000

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.

Click image for the updated attractor applet

Streaming games?

Thor Frølich — Wed, 25 Mar 2009 15:22:51 +0000

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

Thor Frølich — Sun, 15 Mar 2009 22:18:57 +0000

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.

Click here for flow field applet

Particle Ink

Thor Frølich — Mon, 09 Mar 2009 21:21:31 +0000

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.

Click here for the applet

Particles and noise

Thor Frølich — Tue, 24 Feb 2009 08:19:39 +0000

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.

Click here for the noise grid applet

(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

Thor Frølich — Sat, 21 Feb 2009 09:26:45 +0000

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.

Click here for the Fibonacci spiral applet