表达式全局变量

$FPS

每秒回放的帧数 （也可以通过播放栏上的设置修改）.

$FSTART

动画起始帧的帧数字 （也可以通过播放栏上的设置修改）. $NFRAMES (动画帧数) = $FEND - $FSTART + 1.

$FEND

动画末帧的帧数字（也可以通过播放栏上的设置修改）.

$F

当前帧数字， 这是个非常有用的变量，尤其是给渲染的序列帧文件编号

$FF

@Frame

浮点帧数字

$NFRAMES

动画的总帧数 $NFRAMES = $FEND - $FSTART + 1.

$RFSTART

播放栏中显示的第一帧的帧数字。 播放栏可以显示长动画中的特定部分，使你可以专注于编辑这部分动画。 $RFSTART 和 $RFEND 控制播放栏显示特定部分的长度

$RFEND

播放栏中显示的最后一帧的帧数字

$T

@Time

以秒为单位的当前时间， 等同于 ($F-1)/$FPS

$TLENGTH

秒为单位的动画总时长

$TSTART

秒为单位的动画开始时间

$TEND

秒为单位的动画结束时间

$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…).

$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

$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