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This CHOP takes translate, rotate, and/or scale channels and transforms them using the pretransform of the given object. It is primarily used remove the pretransform of a destination object from the output of Object/Transform CHOPs before exporting to the destination object. A combination of Object, PreTransform, and Export CHOPs can be used to perform orientation constraints in objects.
If no input is given, then channels are simply generated from the given
object’s pretransform. If an input is given, the interpretation of the
channels as a transform are defined by the Input Transform Order, and
Translate/Rotate/Scale/Pivot Scope parameters. Any missing transform channels
from an input are filled in using the default value of
1 for the scales,
0 for all others. The input transform is then right-multiplied by
the (usually inverse) pretransform.
To affect only one set of channels coming into the CHOP, use the Scope parameter.
The name of the object to take the pretransform from
Invert the pretransform (This option should be on to remove the pretransform from the input channels.)
Input Transform Order
The transform order of the input channels
The names of the input transform channels
Out Transform Order
The transform order used to generate the output channels
The pivot used to generate the output channels
The output channel names. This can be used to include the object name in the generated channels. If Input Channels is chosen, then the channels will use the same names as its input. If there is no input, then Input Channels behaves the same as Channel Name.
Indicates how much of the channel to cook.
Use Full Animation Range
All of the animated range.
Use Current Frame
Only the sample at the current frame.
Specify the range below.
The start time of the desired interval of the object path.
The end time of the desired interval of the object path.
The left extend conditions.
The right extend conditions.
The default value for extend conditions.
Some of these parameters may not be available on all CHOP nodes.
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:
Matches a single channel name.
chan3 tx ty tz
Matches four channel names, separated by spaces.
Matches each channel that starts with
Matches each channel that has
foot in it.
? matches a single character.
t? matches two-character channels starting with t.
Matches number ranges giving
[xyz]matches three characters, giving channels
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.
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).
When you change the Units parameter, it does not convert the existing parameters to the new units.
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.
Causes the memory consumed by a CHOP to be released after it is cooked and the data passed to the next CHOP.
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
You can leave the Export Prefix blank, but then your CHOP track names need to be absolute paths, such as
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.