Fifty50 (Formerly CreativMotion) posts a look at creating a really cool effect infecting points using Side FX Houdini, VEX and the Solver SOP. Infected points can infect other points in the vicinity.
The effect will have some points take over, or “infect” other points and spread to the next nearest points, until all the points have been taken over by the infection.
The tutorial covers setting infected points, and using VEX to detect the points that are nearest. You will also find out how to loop the VEX code for checking infected points. Finally the Solver SOP is used to spread the infection over time.
VEX is like using a low level language that lets you to make your own nodes in Houdini. VEX runs like C or C++, it evaluates very fast. With VEX you can create custom operators for geometry, volumes, audio, or images, without having to write any code at all.