WrangleSnippetQuickReference

Deborah R. Fowler

Wrangle Node Syntax Quick Reference for Beginners

Posted Oct 17 2018
Updated Nov 6 2020

A really excellent "cheat sheet" by John Kunz https://mrkunz.com/blog/08_22_2018_VEX_Wrangle_Cheat_Sheet.html

For those of you who are less familiar with C-like syntax or are switching back and worth between languages this quick guide to common syntax may be helpful.

Variables

are typed in vex ie.) int, float, string
Newly declared variables have undefined value - INITIALIZE before use
should be named meaningfully (coding standards) ie. hps is not good, hitsPerSecond is good -
name can't be a keyword or start with a number

Random Numbers

float randomNumber = rand(@ptnum);

float randomNumber = random(@ptnum);

Notation

Popular Shorthand	Common Symbols
x = x + 1; x += 1; x++; ++x; // All of these increment x by one ++ prefix increments and then uses ++ postfix uses and then increments	!= == <= >= < > %

Blocks

defined with curly braces
make it visually easy to see these (on their own line - coding standard)

{
}

If/then/else

if ( condition )
{
statements;
}
else
{
statements;
}

Looping

while
for
do while

while( condition )
{
// do something
}

for ( int i = 0; i < something; ++i )
{
// do something
}

do
{
// do something
} while ( condition);

Functions

int myFunction()
{
statements;
return 0; // return some value
}

(must be defined before used)

Procedures (functions that act on data but don't explicitly return a value) - now mostly lumped under the word functions

void myFunction()
{
statements;
}

Parameters/Arguments

int myFunction( int x, float y )
{
        int resultVariable;
        // x and y are parameters and are local to the function
        // they take on the value of the argument
        return resultVariable;
}

To call a function (or procedure) you call its name, for example to run this piece of code

int resultFromCalling = myfunction( 10, 12.6 )

Arrays
int myArray[];

remember counting starts at 0

myArray[0] = 5;

Attributes

@

fetch or creates attributes

in vex snippets attributes can be created and are type specific
For example i@myVar, v@myArray etc.

@ptnum
@numpt
@P
@Cd
@P.x
@Cd.r

int @kermit or i@kermit creates an attribute

List of hard to guess functions:

rint - rounds a number to an integer value (similar to hscript round)

getbbox_size, getbbox_max, (omin, center), also using "op:path" - equivalent to hscript bbox function

sprintf - used for texture override for example

Houdini Resources

Deborah R. Fowler

Wrangle Node Syntax Quick Reference for Beginners