Loading the Stanford Bunny

April 11, 2010

titleI decided to get a little framework set up that would let me play around with some graphics code. As a result, I decided that step one would be to get everyone's favorite test model, the Stanford Bunny, loaded and rendering. I'd never actually used the bunny or any of the other Stanford models before so after a little research into where to access them and what format they were in, I came up with a "pipeline" for loading them into my application. I wouldn't call it a great solution, but it worked pretty well for getting something up and running to play with.



Constraint Relaxation IK in 2D

April 13, 2009

titleInverse kinematics (IK) solvers often become mathematically intensive or computationally expensive with long kinematic chains or when functioning in higher dimensions. I am going to cover an approach to solving IK that is easy to understand, handles any number of joints, and is easy to implement in any dimension. We will walk through a two dimensional example and I'll present sample code to perform the algorithm.



Cyclic Coordinate Descent in 2D

February 11, 2009

titleWhen performing inverse kinematics (IK) on a complicated bone chain, it can become too complex for an analytical solution. Cyclic Coordinate Descent (CCD) is an alternative that is both easy to implement and efficient to process. We will discuss the algorithm works at a high level, followed by a two-dimensional example and sample code.



DISQUS for Joomla

January 15, 2009

titleIn the process of getting my new Joomla! based website up and running, I wanted to add a comment system [Note: My website no longer has a Joomla! backend]. As usual, every free option available had it's own quirks. Some had visual issues, some didn't support threaded replies, and some had conflicts with other Joomla extensions I was using. I ended up liking the DISQUS comment system for Joomla! v1.1 by JoomlaWorks. It integrates the free comment management system, DISQUS, into a site's articles. While I did have to tweak my site template a bit to prevent its JavaScript generated content from drawing over my footer, it covered the rest of my needs.

 

After testing out the plugin for a while, I started to notice a large issue. Anytime an article was viewed with a different URL, it ended up using a different comment thread. In Joomla!, articles can be seen under different URLs for a number of reasons including changing search engine friendly (SEF) URL settings, recategorizing an article, changing your menu, or viewing an article split into multiple pages. Dissapointed to find yet another problematic plugin, I decided to find the root of the problem and fix it.





Analytic Two-Bone IK in 2D

December 29, 2008

titleDue to their complexity, inverse kinematics (IK) problems are often solved with iterative solutions. While iterative solutions can handle different IK poblems with a single algorithm, they can also become computationally expensive. If a specific IK problem needs to be computed often, it is worth considering an analytic solution.

 

If we limit the problem to a two bone chain in a two-dimensions, we can derive the anaytic solution without much complexity. This will generally be more efficient than its iterative alternatives. While this specific case lends itself to a 2D world, it can also be used in 3D as long as the kinematic chain's motion is limited to a single plane.