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This CHOP counts the number of times a channel crosses a trigger or release threshold. It operates in either static or realtime ("Cook to Current Frame") mode.
Crossing the trigger threshold (increasing past the trigger level) creates a trigger event. Similarly, crossing the release threshold (decreasing past the release level) creates a release event. Operations may also be performed while the input remain above or below the trigger or release levels. On each event, the count may be increased or decreased by 1 or the time, or reset to zero. The time per sample varies with the sample rate (i.e. for 100 samples/second, the time for each sample would be 1/100th of a second).
The optional second input is a reset input. The first channel is interpreted as a channel containing reset pulses. Whenever this channel is non-zero, the count for all channels is reset.
This CHOP can be time sliced, and take advantage of Minimal Time Slice Cooks.
Release = Trigger Threshold
If on, the trigger threshold is also used as the release threshold.
The channel level that must be exceeded in order to trigger a count.
A release count is triggered when the channel level drops below this threshold.
The amount of time after a trigger point that a new trigger may occur.
Determines whether a trigger occurs on an increasing slope or decreasing slope when passing the trigger threshold. A release will occur on the opposite slope.
The count can be clamped or looped between the limit minimum and maximum. Clamp will hold the count value at the maximum/minimum value if it goes above or below the limits. Loop will loop the count back between the limits by shifting the count to the maximum or minimum limit.
Minimum allowed count number.
Maximum allowed count number.
Off To On
The operation to perform when a trigger event (off to on) occurs.
The operation to perform while the input remains triggered (on).
On To Off
The operation to perform when a release event (on to off) occurs.
The operation to perform while the input is not triggered (off).
Reset Count To Zero
In time slice mode, this resets the count for all channels.
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.
This example demonstrates how to count impacts from a DOPs simulation using the Count CHOP. Then, using the values from the Count CHOP, we generate copies of a teapot.
The following examples include this node.