Houdini VEX sink

SideFX Houdini VEX #note/sink #code/vex

TOC

Vectors

@v = {1, 1, 1}
v@v = set(x, y, z)

VEX Snippets

parm*=rand(@id+38+ch("seed")); 

random number, linear spread

parm=fit01(rand(@id+31+ch("seed")),ch("min"),ch("max"));

particle age -> Ease in - Ease out

parm*=smooth(ch("start"), ch("end"),@nage);

parameter change in a certain time range

parm=fit(@Frame, ch("start"), ch("end"), ch("start_value"), ch("end_value"));

connect params

parm=fit(@P.y, ch("low"), ch("high"), ch("low_value"), ch("high_value"));

param from age by multiplier

parm*=chramp("parm",@nage);

param from a particle speed

parm=fit(length(@v),ch("speedmin"),ch("speedmax"), ch("valuemin"), ch("valuemax"));

Specifying VEX Data Types

The following characters are used to cast to the corresponding data type.

float       f@name    // Floating point scalar values.
vector2     u@name    // Two floating point values. Could be used to store 2D positions.
vector3     v@name    // Three floating point values. Usually positions, directions, normals, UVW or colors.
vector4     p@name    // Four floating point values. Usually rotation quaternions, or color and alpha (RGBA).
int         i@name    // Integer values (VEX uses 32 bit integers).
matrix2     2@name    // Four floating point values representing a 2D rotation matrix.
matrix3     3@name    // Nine floating point values representing a 3D rotation matrix or 2D transform matrix.
matrix      4@name    // Sixteen floating point values representing a 3D transform matrix.
string      s@name    // A string of characters.

1/100 results in integer, 1/100.0 results in float

Channel Shortcut Syntax

This is used to hint at the data type of auto generated wrangle parameters.

ch('flt1');             // Float
chf('flt2');            // Float
chi('int');             // Integer
chv('vecparm');         // Vector 3
chp('quat');            // Vector 4 / Quaternion
ch3('m3');              // 3x3 Matrix
ch4('m4');              // 4x4 Matrix
chs('str');             // String
chramp('r', x);         // Spline Ramp
vector(chramp('c', x)); // RGB Ramp