Transform channel node

Takes translate, rotate, and/or scale channels and transforms them using the transform parameters in the CHOP.

All Parameters Local variables

See also: Pretransform

This CHOP takes translate, rotate, and/or scale channels and transforms them using the transform parameters in the CHOP. It can be used to:

At present, only one transform format exists: the transform defined by 12 channels (tx ty tz, rx ry rz, sx sy sz, px py pz) and a transform order.

The Transform CHOP expects the input channels to have names that end in the above names. Examples are:

geo1:tx geo1:ty geo1:tz geo1:rx ...
headtx heaty headtz headrx
tx ty tz rx ...  (what you would get from a Fetch chop)
The above defines a transformation matrix. This is multiplied by the transform matrix defined on the Transform tab, and output as translate/rotate/etc. channels.

To affect only one set of channels coming into the CHOP, use the Scope parameter.

Parameters

Transform

Overview

This page defines the matrix used to transform the channels. The parameters used to create this matrix are Transform Order, Rotate Order, and the Translate, Rotate, Scale and Pivot parameters.

Output Channels

Currently there is only one output type, the transformed input channels.

Matrix Operation

The input channels can be pre or post multiplied by the transformation.

Use Rotation Hint

Supply approximate starting values for the rotation channels.

Input

Overview

This page defines what the incoming channels' transform order is assumed to be. Using the incoming channels and the transform order here, a matrix for the incoming channels is built. It is then multiplied by the transformation matrix defined on the Transform tab. Any missing translation, rotation or scale channels will default to zero (or one in the case of scale).

Transform Order

The transform order of the input channels.

Rotate Order

The rotation order of the input rotations.

Common

Some of these parameters may not be avaiable on all CHOP nodes.

Scope

To determine which channels get affected, some CHOPs have a scope string. Patterns can be used in the scope, for example * (match all), and ? (match single character).

The following are examples of possible channel name matching options:

chan2

Matches a single channel name.

chan3 tx ty tz

Matches four channel names, separated by spaces.

chan*

Matches each channel that starts with chan.

*foot*

Matches each channel that has foot in it.

t?

The ? matches a single character. t? matches two-character channels starting with t.

r[xyz]

Matches channels rx, ry and rz.

blend[3-7:2]

Matches number ranges giving blend3, blend5, and blend7.

blend[2-3,5,13]

Matches channels blend2, blend3, blend5, blend13.

t[xyz]

[xyz]matches three characters, giving channels tx, ty and tz.

Sample Rate Match

The Sample Rate Match Options handle cases where multiple input CHOPs’ sample rates are different.

Resample At First Input’s Rate

Use rate of first input to resample others.

Resample At Maximum Rate

Resample to highest sample rate.

Resample At Minimum Rate

Resample to the lowest sample rate.

Error if Rates Differ

Does not accept conflicting sample rates.

Units

The units for which time parameters are specified.

For example, you can specify the amount of time a lag should last for in seconds (default), frames (at the Houdini FPS), or samples (in the CHOP’s sample rate).

Note

When you change the Units parameter, it does not convert the existing parameters to the new units.

Time Slice

Time Slicing is a feature which boosts cooking performance and reduces memory usage. Traditionally, CHOPs calculate the channel over its entire frame range. If the channel does need to be evaluated every frame, then cooking the entire range of the channel is unnecessary. It is more efficient to calculate only the fraction of the channel that is needed. This fraction is known as a Time Slice.

Unload

Causes the memory consumed by a CHOP to be released after it is cooked and the data passed to the next CHOP.

Export Prefix

The Export prefix is prepended to CHOP channel names to determine where to export to.

For example, if the CHOP channel was named geo1:tx, and the prefix was /obj, the channel would be exported to /obj/geo1/tx.

Note

You can leave the Export Prefix blank, but then your CHOP track names need to be absolute paths, such as obj:geo1:tx.

Graph Color

Every CHOP has this option. Each CHOP gets a default color assigned for display in the Graph port, but you can override the color in the Common page under Graph Color. There are 36 RGB color combinations in the Palette.

Graph Color Step

When the graph displays the animation curves and a CHOP has two or more channels, this defines the difference in color from one channel to the next, giving a rainbow spectrum of colors.

Local variables

I

The current index.

Usages in other examples

Example name Example for