Since | 15.5 |
This CHOP interprets the input channels as a position vector and creates a channel with a value of 1 where the positions are stationary. This is useful for creating channels that describe when a character’s feet are planted, which can be used for foot locking in a crowd simulation.
Parameters ¶
Source
Specifies the source of the position data.
Input Channels
The input channels are interpreted as a position vector.
Object
Uses the position of the Target Object relative to the Reference Object.
Agent
Uses the world space position of an agent’s bone.
Target Object
The object that is being compared to the reference object when Source is Object.
Reference Object
Optional object that acts as the basis for the comparison when Source is Object.
Offset
Specifies a local space position in the Target Object when Source is Object, or in the Transform Name when Source is Agent.
Frame Range
Specifies the frame range of the clip when Source is Object.
SOP Path
The path to a SOP containing an agent primitive. If the geometry contains multiple agent primitives, the first primitive in the Group will be used.
Group
Specifies a primitive group for the SOP geometry.
Clip Name
The name of an animation clip in the agent primitive’s definition.
Transform Name
The name of a transform in the agent primitive’s rig.
Method
Specifies the method used to determine when the joint is planted.
Speed Threshold
The joint is considered planted when its speed is less than the Speed Threshold.
Distance from Terrain
The joint is considered planted when it is within Distance Threshold of the terrain. This can provide more robust behaviour than the Speed Threshold method (such as when analyzing the ankle joint if a character is standing on their toes), but requires terrain geometry.
Speed Threshold
The speed threshold to use when determining if the joint is nearly stationary.
Terrain Source
Specifies the source of the terrain geometry when Method is Distance from Terrain. This can either be a path to SOP geometry or a manually-specified plane.
SOP Path
The SOP geometry used when Method is Distance from Terrain and Terrain Source is SOP.
Plane Origin
The origin point of the plane used when Method is Distance from Terrain and Terrain Source is Plane.
Plane Normal
The normal of the plane used when Method is Distance from Terrain and Terrain Source is Plane.
Distance Threshold
The maximum distance from the terrain where the joint is considered planted.
Channel Name
Specifies the name of the new channel.
Blend In Frames
Specifies the number of frames over which the channel value changes from 0 to 1 before the foot plant begins.
Blend Out Frames
Specifies the number of frames over which the channel value returns to 0 after the foot plant ends.
Common ¶
Some of these parameters may not be available on all CHOP nodes.
Scope
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:
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.
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 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.
Units
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).
Note
When you change the Units parameter, the existing parameters are not converted to the new units.
Time Slice
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.
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 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.
See also |