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This CHOP treats its multiple-inputs as keyframes and interpolates between them. The inputs are usually single-frame CHOPs like those produced by a Constant CHOP. The Interpolate CHOP first sorts the input CHOPs in time (without shifting them) and interpolates between them to fill the gaps.
The number of channels in the output is the same as the number of channels in the first input.
If a channel is missing in an input, and Match By is set to Name, it is treated as if there is no keyframe at that frame for that channel, and the interpolation occurs between CHOPs before and after that frame.
When the graph is displayed as timebars, and you click on the black lines of the Interpolate CHOP time bar which represent the inputs of the CHOP, you can drag the line to change the time of that input. It goes to that input and changes the value if its “start” parameter, so you can re-time the keyframes.
When you Shift-click on a black line, the current CHOP changes to the corresponding input, so you can edit its values.
This CHOP has Sample Rate Match options in the Common page.
The shape of the interpolation curve.
A straight line.
Ease In Ease Out
Half cosine blend.
A cubic spline.
Overlapping parts, if any, are added.
If an input is not a single frame, and if there are overlaps in the input CHOPs, an option is used to resolve the conflict.
First Segment has Priority
Use the segment with the earliest start time.
Last Segment has Priority
Use the segment with the latest start time.
Combine the conflicting channels by averaging them.
Matches channels between inputs by either index or name.
It is sometimes desirable to produce a warning or an error when channels in the first input fail to be correctly matched to channels in the other inputs. A failure may occur when matching by Channel Number if an input has fewer channels than input 1, or when matching by Channel Name if a channel name cannot be found in input 1.
Some of these parameters may not be available on all CHOP nodes.
To determine the channels that are affected, some CHOPs have a scope string. Patterns can be used in 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 the rate of the first input to resample the others.
Resample At Maximum Rate
Resample to the 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 of the time parameters.
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, the existing parameters are not converted to the new units.
Time slicing is a feature that boosts cooking performance and reduces memory usage. Traditionally, CHOPs calculate the channel over its entire frame range. If the channel needs 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 the 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 to it for display in the graph, but you can override the color with the 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.