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Since | 16.0 |
Extracts the required skin and guide curves from a groom object such as a Guide Groom or Guide Deform. These nodes can also write their groom data to files which can be imported by this node.
Parameters ¶
Groom Source ¶
Source Mode
Groom Object
Load the groom from a groom object.
Groom File
Load the groom from a file.
Groom Object
Load the groom data from this source object.
Groom File
Load the groom data from this file.
Use Object Transform
Take this object’s transform into account when simulating curves.
Dynamics ¶
Enable Dynamics
Enables dynamics simulation.
Reset Simulation
Clears the entire simulation cache. When viewing a DOP Network in the viewport, a button will be made active above the viewport on the right hand side. Pressing that button performs exactly the same action as pressing this Reset Simulation button.
Cache Simulation
Enables the simulation cache. Many solvers will not work properly unless this option is enabled. However for very large simulations, turning off this option is the best way to guarantee the smallest possible memory footprint for the simulation.
Create External DOP Network
Copy the internal DOP network to an external one for editing.
Use External DOP Network
Fetch the simulation from an external DOP network.
Guide DOP Object
Get the simulation output from this DOP object.
Use Freeze Frame
Freeze the simulation in time.
Freeze Frame
Freeze the simulation at this frame.
Display ¶
Display As Subdivision Curves
Subdivide curves in the viewport for smoother display.
Display Color
Display curves in this color in the viewport.
Simulation ¶
Start Frame
The default offset time expression references this parameter to set the offset time appropriately. This allows one to set the start time in frames rather than seconds which can be more straightforward in some cases. If the start frame is set to 24, the simulation will not start cooking until frame 24. Note that if you use this, $SF and $F will no longer refer to the same thing inside the simulation.
Scale Time
Specifies a scale factor that relates global time to the
simulation time for this DOP Network. A value greater than
one means the simulation time advances faster than the
global time. A value less than one causes the simulation to
appear to run in slow motion relative to the global time.
Several expression functions such as doptime
exist for
converting from global times to simulation times and vice
versa.
Spatial Scale
Indicates the scale of the simulation. It is very important that you set this to the right value, otherwise the defaults for stiffness and damping will not work as expected.
Note
You should choose the correct Unit Length in Edit > Preferences > Hip File Options before you create your DOP network. That way, the wire solver node will automatically get the correct Spatial Scale when it’s created.
Minimum Substeps
Limits the minimum number of substeps per timestep. Higher values may be more accurate, but may require more computation.
Solve Tolerance
Determines how close to the actual value the formula must solve before continuing to solve the next frame.
A smaller value will give higher quality, but will also run slower. A larger value will run faster, but may not be as accurate.
Max Collision Resolve Passes
The maximum number of passes that are performed to resolve the collisions. When this number is set too low, there is a chance that not all collisions will be resolved, whch could result in visible penetrations.
Physical ¶
Physical Parameters ¶
Compute Mass
Determines if the mass will be calculated automatically from the object’s density and volume.
Density
The mass of a wire object is its volume times its density. The volume is affected by the width parameter.
Mass
The absolute mass of the object.
Width
The width of the wire object defines the diameter of each cylindrical section.
Friction
The coefficient of friction of the object. A value of 0 means the object is frictionless. This governs how much the tangential velocity is affected by collisions.
Dynamic Friction Scale
An object sliding may have a lower friction coefficient than an object at rest. This is the scale factor that relates the two. It is not a friction coefficient, but a scale between zero and one.
A value of one means that dynamic friction is equal to static friction. A scale of zero means that as soon as static friction is overcome the object acts without friction.
Elasticity ¶
Linear Spring Constant
This parameter defines how strongly the wire resists stretching.
Linear Damping Constant
This parameter defines how strongly the wire resists oscillation due to stretch forces.
Angular Spring Constant
This parameter defines how strongly the wire resists bending.
Angular Damping Constant
This parameter defines how strongly the wire resists oscillation due to bending forces.
Adjust For Length
Enabling this parameter will adjust spring and damper strengths according to segment lengths. This allows wire flexibility behavior to be independent of segment resolution.
Adjust For Mass
Enabling this parameter will adjust spring and damper strengths according to segment masses. This allows wire flexibility behavior to be independent of mass.
Reference Matching
Values greater than zero cause all curves to behave more like curves that are as long as Reference Length. This causes hairs that are longer than the reference length to bend less and curves that are shorter to bend more.
Reference Length
The reference length used by Equal Length Behavior.
Plasticity ¶
Stretch Threshold
This parameter defines the amount of stretching allowed before the wire is permanently stretched.
Stretch Rate
This parameter defines how quickly a wire’s permanent shape becomes stretched.
Stretch Hardening
This parameter defines how a wire becomes stiffer (if greater than 1) or weaker (if less than 1) when permanently stretched.
Bend Threshold
This parameter defines the amount of bending allowed before the wire is permanently bent.
Bend Rate
This parameter defines how quickly a wire’s permanent shape becomes bent.
Bend Hardening
This parameter defines how a wire becomes stiffer (if greater than 1) or weaker (if less than 1) when permanently bent.
Forces ¶
Target ¶
Target
Enable a force which causes curves to stick more closely to their predefined shape.
Target Stiffness
This parameter defines how strongly the wire resists deforming from the animated position.
Target Damping
This parameter defines how strongly the wire resists oscillation relative to the animated position.
Gravity ¶
Gravity
Enable Gravity
Force
The magnitude of gravity.
Wind ¶
Wind
Enable the wind force.
Velocity
The wind field’s velocity.
Strength
The strength with which curves adjust to the wind’s velocity.
Noise ¶
Seed
Random seed for the noise.
Turbulence
The number of noise generations to use.
Roughness
The amplitude reduction of higher frequency noise contributions.
Exponent
Raises the noise to the given exponent.
Frequency
The scale of the noise. Decreasing frequency increases feature size.
Minimum Value
Sets the minimum value that can be generated by the noise field.
Maximum Value
Sets the maximum value that can be generated by the noise field.
Offset
Allows the noise field to be effectively moved through space.
Drag ¶
Normal Drag
The component of drag in the directions normal to the wire. Increasing this will make the wire go along with any wind that blows against it. For realistic wire-wind interaction, the Normal Drag should be chosen larger (about 10 times larger) than the tangent drag.
Tangent Drag
The component of drag in the direction tangent to the wire. Increasing this will make the wire go along with any wind that blows tangent to the wire.
Constraints ¶
Roots ¶
Root Constraint
Controls the way curve roots are constrained to the input groom.
Position & Orientation
Match position and direction of roots to the input groom. This causes curves to stick out of the skin in the direction of the groom.
This sets the gluetoanimation
attribute of root points to 1
.
Position
Match the position of roots to the input groom. Curves will drop & swing freely as the direction is not constrained at all.
This sets the pinttoanimation
attribute of root points to 1
.
Clumping ¶
Create Clump Constraints
Max Guides Per Clump
Only create clump constraints for clumps that have at most this number of guides.
All the unclumped guides in a groom belong to the same clumpid. Without this limit, these guides would be considered a clump and constraints would be created between them.
Display Clump Constraints
Display clump constraints in the viewport.
Collisions ¶
Wire-Wire ¶
Self Collisions
Compute collisions with other parts of the same guide curve.
Wire-Geometry ¶
Collision Handling
Determines the collision detection and resolution strategy used by the wire solver.
SDF
A strategy that supports SDF representations of rigid bodies.
Local Geometric
A collision response strategy that ignores the influence of elements distant from the collision. This strategy is faster that “Global Geometric” but may produce visual artifacts.
Global Geometric
A collision response strategy that considers the influence of all elements.
Repulsion
A repulsion force is applied to gently push apart these pieces of geometry when the two pieces of geometry overlap (including overlap of the collision width). This parameter controls the strength of the force.
Skin ¶
Collide With Skin
Compute collisions with the skin geometry.
VDB Source
Compute From Geometry
Compute the required collision volume internally. This is done using VDB volumes.
SOP Volume
Fetch a collision volume from a specified SOP path.
Voxel Size
The voxel size to use when computing the collision volume.
Fill Interior
Computes distance values for the entire interior of the object. This ensures that collision detection works even deep inside the object, but can greatly increase the computation time and space requirements of the volume.
Interior Band
How far into the object to compute distance values when Fill Interior is disabled.
Volume SOP
The SOP path to get the collision volume from when VDB Source is set to SOP Volume.
External ¶
Collide With External Geometry
SOP Path
The SOP path to fetch the external collision geometry from.
VDB Source
Compute From Geometry
Compute the required collision volume internally. This is done using VDB volumes.
SOP Volume
Fetch a collision volume from a specified SOP path.
Voxel Size
The voxel size to use when computing the collision volume.
Fill Interior
Computes distance values for the entire interior of the object. This ensures that collision detection works even deep inside the object, but can greatly increase the computation time and space requirements of the volume.
Interior Band
How far into the object to compute distance values when Fill Interior is disabled.
Volume SOP
The SOP path to get the collision volume from when VDB Source is set to SOP Volume.
Caching ¶
See the File Cache SOP help for these parameters.
Locals ¶
See also |