Example of manipulating geometry with Houdini VEX

noise_in_houdini_vex.vfl

// using houdini's built in noise functions
// in the VEX expression language
// http://www.sidefx.com/docs/houdini/vex/index.html

// this is a Point Wrangle, meaning this code will be called
// for every point in the geometry
// each time it is called @P is equal 
// to a different point in the geo

// params are located on the attribute wrangle
float noiseStrength = ch("noise_strength");
float noiseAnim = ch("noise_anim");

// the noise uses the point locations for a seed
// but added a fourth coord as a parameter to 
// animate it without moving geo's points
vector4 coords = set(@P.x, @P.y, @P.z, noiseAnim);

// scale noise to -0.5 to 0.5
vector negativeOffset = set(-0.5, -0.5, -0.5);
vector theNoise = noise(coords) + negativeOffset;

// parameterize amount that noise affects geo
theNoise *= noiseStrength;

// displace geometry
@P += theNoise;