I first started programming PewPew on Linux, with portable librairies (OpenGL/SDL/libcurl). Of course, I had the iPhone/iPod touch in mind, so I designed the gameplay and the UI accordingly. After a month or two (once I payed for the $99 for the SDK), I migrated to Xcode and the iPhone OS. I'll write a post about that later because it was not as simple as I imagined it would be. A week ago, I migrated the code back to Linux, and this time it only took a couple of days :) The goal was to make PewPew prettier by giving the lines a glowing look (like geometry wars) by using the infinite power of my computer (compared to the iphone anyway). Perfection. Naturally, at first I failed :-) My first idea was to draw the lines multiple times, with different width and different transparencies. Here's what it looked like: Not perfection. Okay so that was ugly, but it had to be done. The second idea was to use pixel shaders. A pixel shader is small routine executed on the graphic card, that...