http://www.mlesniak.com Thoughts about programming and my little pet projects Tue, 16 Dec 2008 10:09:07 +0000 http://backend.userland.com/rss092 en The Two Rules of Success: Don't tell everything you know. (thanks to Jens!) http://www.mlesniak.com/2008/12/16/the-two-rules-of-success/ Small update: You can see the code live here if my computer is online. The "new" Javascript libraries ease the use of AJAX a lot: With these two simple code snippets (A simple Servlet for searching through /usr/share/dict/words and a simple jQuery/Javascript -Script) I was able to create an autocompletion form in ... http://www.mlesniak.com/2008/10/18/easy-ajax-using-jquery/ I want to play around a bit with modern web technologies and JavaScript (AJAX, JQuery, JavaScript in general) and was in need of a webserver. Since all I found where either difficult to setup or quite complex to configure (and I was bored so wanted something to hack, too) I ... http://www.mlesniak.com/2008/10/18/apaches-little-brother/ Finally I found some really mean bugs and I've learned again that in 99.9% of the time the source of the bug is neither the JVM, the language or the algorithm but the person in front of the computer ;-). The (non-parallel!) implementation of Barnes-Hut runs for ca. 77 seconds ... http://www.mlesniak.com/2008/10/11/improved-barnes-hut/ At the moment I'm implementing the Barnes-Hut O(n log n) algorithm for n-Body problems. This will be my initial point for further research on some special parallel aspects of it. (Screenshot of a visualization of the Barnes-Hut Quadtree and Center of masses) http://www.mlesniak.com/2008/10/07/barnes-hut/ Since I'm currently working (as part of my research) on some special optimizations of n-Body problems I don't have a lot of time for the raytracer. Here's a screenshot of the framework I've written to test my ideas. You see a non-parallel all-pairs simulation of 10 Bodies: (click for a bigger ... http://www.mlesniak.com/2008/09/18/side%c2%b2-project-research/ Prozedural textures were easier to implement than I thought. But without antialiasing it looks quite ugly: It's a bit better when the resolution is much higher: (Click on the image for a version in 1600x1000) http://www.mlesniak.com/2008/09/10/prozedural-textures/ Doing some stress tests at the moment... http://www.mlesniak.com/2008/09/10/multiball/ Not quite Phong-Shading, but at least my spheres are shaded now. Implemented the possibility for multiple light soures, different light intensities, switchable shadows and especially shading (based on the simple Lambertian-Model): A video showing how changing the light intensity alters the scene is here: PS: While I was developing, I played a ... http://www.mlesniak.com/2008/09/10/shading/ It seems there was an error in the formula for the ray-sphere intersection calculation -- after calculating a few samples and the general formula manually, I found them. This was quite surprising, because -- lazy as I am -- I took the formulae from a book about graphic programming. Anyway, ... http://www.mlesniak.com/2008/09/10/bug-hunting/