Parameter expressions

http://www.sidefx.com/docs/houdini/network/expressions.html

HScript global variables
Tip

Some global variables have equivalents that start with @ to match variables available in VEX snippets.

Playback
$

@

Description

$FPS

Playback speed in frames per second (as set with the Playbar controls).

$FSTART

Frame number of the first frame of animation (as set with the Playbar controls). $NFRAMES (the number of frames in the animation) = $FEND - $FSTART + 1.

$FEND

Frame number of the last frame of animation (as set with the Playbar controls).

$F

The current frame, (as set with the Playbar controls). This is a very useful variable, especially for rendered picture filename numbering.

$FF

@Frame

Floating point frame number.

$NFRAMES

Number of frames in the animation. $NFRAMES = $FEND - $FSTART + 1.

$RFSTART

Frame number of the first frame shown in the playbar. The playbar can show a subset of the total number of frames, allowing you to focus on a particular section of a long animation. $RFSTART and $RFEND control the subset of frames shown in the playbar.

$RFEND

Frame number of the last frame shown in the playbar.

$T

@Time

Current time in seconds. Equals ($F-1)/$FPS

$TLENGTH

Total length of animation in seconds.

$TSTART

Start time of animation in seconds.

$TEND

End time of animation in seconds.

General
$ACTIVETAKE

Contains the name of the current take.

$E

The mathematical constant e (2.71828…).

$HFS

The directory where Houdini is installed.

$HH

$HFS/houdini.

$HIP

The directory containing the current scene file.

$HIPFILE

The full path of the current scene file, including the file extension.

$HIPNAME

The name of the current scene file without the extension. You can use this to build filenames with different extensions based on the scene name.

$HOME

Your home directory.

$JOB

The project directory.

$PI

The mathematical constant pi (3.1415926…).

Channels
$OS

Operator String. Contains the current OP’s name.

$CH

Current channel name.

$IV

In value (value at start of segment).

$OV

Out value.

$IM

In slope

$OM

Out slope

$IA

In acceleration

$OA

Out acceleration

$LT

Local time - not including stretch or offset

$IT

Start time of segment

$OT

End time of segment

$LIT

Local start time of segment

$LOT

Local end time of segment

$PREV_IT

Previous segment start time

$NEXT_OT

Next segment end time

COPs
$CSTART

Start frame of the current COP.

$CEND

End frame of the current COP.

$CFRAMES

Number of frames for the current COP.

$CFRAMES_IN

Number of frames available from the first input COP.

$CINC

Gets the global frame increment value.

$W

Current image width.

$H

Current image height

Render nodes
$N

Current frame being rendered.

$NRENDER

Number of frames being rendered.


September 7, 2018
2

zplus for fire

temperature diffusion: 0.02

gas released: 1.5

temperature output: 0.5

Burn rate: 0.75

advect fuel: 0.95

disturbance and turbulance

i/o temperature vel density

vol viz---

dens field densitity

emissioin field temp . scale 10

emission color field temp x preset blackbody

September 6, 2018
2
Pyro

SIM properties

//All on points after the assemble packed.

i@active = chi("active");
i@animated = chi("animated");
s@collisiongroup = itoa(chi("collision_group")); 
s@collisionignore = itoa(chi("collision_ignore"));
August 18, 2018
5
RBD
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