12.0 Expressions

https://www.sidefx.com/docs/houdini/ref/expression_cookbook.html
https://www.sidefx.com/docs/houdini/expressions/index.html

12.1 Channel lookups

ch()
Returns the value of a parameter.

chramp()
chs()
Evaluates the string value of a parameter at the current time.

chf()
Evaluates a parameter at a given frame.

12.2 Current frame

$FF or @Frame (sub-frames)
$F
$SF (simulation frames)

12.3 Current time

$T or @Time

12.4 Random number

rand($F)

12.5 Fit range

fit01(n, newmin, newmax)

12.6 Trigonometric functions

cos(@ptnum * 2)
sin()

12.7 Conditions

if ($F<12, $F, 75)

12.8 Attributes

prim("/obj/geo1/facet1", 3, "P", 0)
Evaluates the X component of the centroid of primitive 3 in the specified surface node.

point("/obj/geo1/facet1", 3, "P", 0)
Returns the X component of point 3 of the facet1 surface node in geo1.

detail("/obj/geo1/attribpromote1", "area", 0)

floor()

12.9 Other

abs()
Returns the absolute value of the argument.

sqrt()

atof()
Converts a string to a float

bbox()
Returns bounding box information for a surface node

chop()
Evaluates a channel within a CHOP at the current time.

clamp()
Returns a value clamped between a minimum and maximum.

cross()
Computes the cross-product of two vectors.

dot()
Computes the dot product of two vectors.

max()
Returns the larger of two values.

normalize()
Normalizes a vector.

opdigits()
Returns the numeric suffix of a node name.

padzero()
Returns a string padding a number to a given length with zeros.
padzero(5, 126) = 00126

smooth()
Takes a value and range and returns a smooth interpolation between 0 and 1.
smooth ($F, 12, 55)
This example will generate an ease-type curve between values 0 and 1,
starting at frame 12 and ending at frame 55. Dig it!