Carbon N-Lattice¶
Description¶
This node defines a Carbon N-Lattice simulation object, its import geometry, and the N-Lattice parameters.
A Carbon N-Lattice is a hybrid object, containing multiple lattices, each made of several Carbon dynamic elements. It can be used for a wide range of applications such as feathers, hair, fur, foliage, plants, …etc.
An animated Carbon N-Lattice with individual lattices growing and conforming.
A lattice must be a grid-like geometry with each of its points numbered from left to right and bottom to top.
Each lattice is made of a rigid shaft that is welded to a soft body.
This must be specified through a shaft point attribute painted on the
reference lattice where rigidity to the joint attachment of the lattice is
required.
A typical 6x9 lattice feather. Note the directions of the points numbering and the flipped edges 5-10 and 46-53 to prevent weak corners. Yellow points denote a typical shaft rigid attachment.
A N-Lattice reference geometry contains the complete set of lattices, which can be authored individually. This geometry can be animated when needed.
Warning
When using a N-Lattice setup, you must carefully set the Lattice Width parameter. For example, the 6x9 lattice above being a grid of 6 points in width will require a Lattice Width of 6. Using an acceptable but wrong value (such as the grid height instead of width) will not give an error but yield a visual result that will simulate incorrectly.
See the N-Lattice User Guide for more in depth information.
Parameters¶
Activation activation
Enable this object. Use 0 to disable, any other value to enable.
N-Lattice¶
Animated Geometry geometryAnimated
Enable animated N-Lattice geometry.
Note
It is a good practice to leave this toggled off when not using
animated parameters because it impacts performance.
N-Lattice SOP Path nLattice
Path to the SOP geometry defining the N-Lattice.
Note
This must be the lattices in normal configuration when a Groom Pose with individual lattice angles is provided.
Groom SOP Path groomPose
Path to the SOP geometry defining the N-Lattice Groom Angles. This parameter is required in order to have a Swing Lead-In to the individual lattice angles and have access to the Groom Angles Angle Limit.
Base Name baseName
Prefix of the name primitive attribute output used to mark the geometry of each lattice.
Root Offset rootOffset
Lattice root offset in surface normal direction. Must be greater or equal to the Collider Outer Fatness positioned underneath the lattices if any.
Growth Lead-In leadScales
The lead-in time in number of frames spent growing the lattices.
Note
Any value different than 0 will force the Animated flag during the growth lead-in.
Swing Lead-In leadAngles
The lead-in time in number of frames spent swinging the lattices to their reference angles/positions.
Note
Either a Groom Pose geometry or the Override Angles mode must be specified for the Swing Lead-In to be activated.
Animated Angles anglesAnimated
Enable animated parameters for this section by evaluating and updating the values at every frame.
Note
It is a good practice to leave this toggled off when not using
animated parameters because it impacts performance.
Groom Angles
Extract all lattices’ resting angles from the Groom Pose.
Angle Limit angleLimit
Angular swing limit per lattice.
Note
A Groom Pose geometry must be specified for the Angle Limit to be activated.
Override Angles
Override all angles described by the Groom Pose, if any, and set all lattices to conform to the same resting angle.
Angle angle
Lattice’s resting angle, set equally for all lattices.
Animated Springs springsAnimated
Enable animated N-Lattice springs controlling the lattices’ orientation.
Note
It’s good practice to leave this toggled off when not using
animated parameters because it impacts performance.
Base Parameters
Swing Stiffness swingStiffnessBase
The joint swing angular stiffness.
Swing Viscosity swingViscosityBase
The joint swing angular viscosity.
Twist Stiffness twistStiffnessBase
The joint twist angular stiffness.
Twist Viscosity twistViscosityBase
The joint twist angular viscosity.
Painted Attribute Range
Swing Stiffness swingStiffnessRange
The multiplier of the painted primitive attribute values that add up to the base parameter.
Note
Painted primitive attribute name: swingStiffness
Swing Viscosity swingViscosityRange
The multiplier of the painted primitive attribute values that add up to the base parameter.
Note
Painted primitive attribute name: swingViscosity
Twist Stiffness twistStiffnessRange
The multiplier of the painted primitive attribute values that add up to the base parameter.
Note
Painted primitive attribute name: twistStiffness
Twist Viscosity twistViscosityRange
The multiplier of the painted primitive attribute values that add up to the base parameter.
Note
Painted primitive attribute name: twistViscosity
Static Friction staticFriction
Lattices’ static friction, greater than or equal to 0 and greater than or equal to dynamic friction.
See also
Dynamic Friction dynamicFriction
Lattices’ dynamic friction, greater than or equal to 0 and smaller than or equal to static friction.
See also
Form Drag formDrag
Aerodynamics form drag. Shapes with a large apparent cross section exposed to the air flow and with a high form drag coefficient will receive more drag than thinner ones.
Warning
Explicit force, so high values can produce instability.
See also
Skin Drag skinDrag
Aerodynamics skin drag. Friction of the skin against the air flow. Usually much smaller, and never bigger than form drag.
Warning
Explicit force, so high values can produce instability.
See also
Lift lift
Aerodynamics lift. Lift force coefficient.
Warning
Explicit force, so high values can produce instability.
See also
Lattice¶
Lattice Grid SOP Path lattice
Path to the SOP geometry defining the lattice geometry.
Lattice Width latticeWidth
Number of points in the lattice grid horizontal direction. The lattice points are numbered from left to right and bottom to top and the lattice grid should at least be 2x2 points in resolution.
Warning
It is important to set the correct value for this parameter so that the lattices’ position and center of mass can be correctly calculated. Using an acceptable but wrong value (such as the grid height instead of width) will not give an error but still yield a visual result that will simulate incorrectly.
Outer Fatness outerFatness
Lattice’s outer volume thickness (can be null for a single sided collider).
See also
Mass mass
Lattice’s mass in kg.
Base Parameters
Welding Radius weldingRadiusBase
Lattice’s soft-welding radial limit, how far the lattice is allowed to move away from its rigid attachment points.
Note
It is recommended to use at least a small radius for most applications. Soft-welding is a simple way to handle over-constrained situations, reducing jiggling and increasing stability.
Welding Stiffness weldingStiffnessBase
Lattice’s soft-welding stiffness coefficient, keeps the lattice from moving away from its rigid attachment points.
Note
Enabled when the Welding Radius (Base or Range) is greater than zero.
Welding Viscosity weldingViscosityBase
Lattice’s soft-welding viscous ratio, the damping of the lattice moving around its rigid attachment points.
Note
Enabled when the Welding Radius (Base or Range) is greater than zero.
Painted Attribute Range
Welding Radius weldingRadiusRange
The multiplier of the painted primitive attribute values that add up to the base parameter.
Note
- Enabled when the Welding Radius (Base or Range) is greater than zero.
- Painted primitive attribute name:
weldingRadius
Welding Stiffness weldingStiffnessRange
The multiplier of the painted primitive attribute values that add up to the base parameter.
Note
- Enabled when the Welding Radius (Base or Range) is greater than zero.
- Painted primitive attribute name:
weldingStiffness
Welding Viscosity weldingViscosityRange
The multiplier of the painted primitive attribute values that add up to the base parameter.
Note
- Enabled when the Welding Radius (Base or Range) is greater than zero.
- Painted primitive attribute name:
weldingViscosity
Self Collide selfCollide
Enable self-collision for each lattice against itself.
Toggling this off can improve performance but causes
self-interpenetrations.
Base Parameters
Surface Compression surfaceCompressionBase
Lattice’s surface compression, must be strictly greater than 0 and smaller than or equal to extension.
See also
Surface Extension surfaceExtensionBase
Lattice’s surface extension, must be strictly greater than 0 and greater than or equal to compression.
See also
Surface Pressure surfacePressureBase
Lattice’s pressure. Unit in mass/length/time^2.
Describes the force per area over a surface map exercised by a virtual fluid.
Warning
Explicit force, so high values can produce instability.
See also
Painted Attribute Range
Surface Compression surfaceCompressionRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: surfaceCompression
Surface Extension surfaceExtensionRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: surfaceExtension
Surface Pressure surfacePressureRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: surfacePressure
Base Parameters
Stretch Stiffness stretchStiffnessBase
Lattice’s stretch stiffness (mass/time^2).
See also
Stretch Viscosity stretchViscosityBase
Lattice’s stretch viscosity (dimensionless).
See also
Stretch Compression stretchCompressionBase
Lattice’s stretch compression, must be strictly greater than 0 and always be smaller than or equal to extension.
See also
Stretch Extension stretchExtensionBase
Lattice’s stretch extension, must be strictly greater than 0 and always greater than or equal to compression.
See also
Stretch Equilibrium stretchEquilibriumBase
Lattice stretch resting length (equilibrium) as a ratio of the reference length.
Use 1 for the default resting position.
See also
Painted Attribute Range
Stretch Stiffness stretchStiffnessRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: stretchStiffness
Stretch Viscosity stretchViscosityRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: stretchViscosity
Stretch Compression stretchCompressionRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: stretchCompression
Stretch Extension stretchExtensionRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: stretchExtension
Stretch Equilibrium stretchEquilibriumRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: stretchEquilibrium
Base Parameters
Bend Stiffness bendStiffnessBase
Lattice’s angular stiffness (mass * length^2 / time^2 / degree).
See also
Bend Viscosity bendViscosityBase
Lattice’s angular viscosity (dimensionless).
See also
Bend Limit bendLimitBase
Lattice’s crease angular limit (degree), between 0 and 180 degree.
See also
Painted Attribute Range
Bend Stiffness bendStiffnessRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: bendStiffness
Bend Viscosity bendViscosityRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: bendViscosity
Bend Limit bendLimitRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: bendLimit
Base Parameters
Viscous Damping viscousDampingBase
Lattice’s viscous damping (1/time), damping control over the nodes’ group cohesion.
See also
Painted Attribute Range
Viscous Damping viscousDampingRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: viscousDamping
Parameter File¶
Use Parameter File fileOverride
Replace parameter values by expressions fetching the values from the loaded parameter file. Parameter values from the exclusion filter are left unchanged.
File Name fileName
Json file path to save this node’s current parameters to, and load the parameter file from.
Save save
Save this node’s current parameters to the specified file.
Load load
Load or reload the specified parameter file. As the overriding expressions always fetch values from the last loaded parameter file, and not from the file itself, use this button to refresh the loaded current parameter file with the values on disk.
Reload Every Time The Node Is Loaded reload
Automatically reload the parameter file when the scene is loaded. If the specified file cannot be found then the overriding expressions will use the values of the last loaded parameter file instead.
Exclusion Filter exclusionFilter
The exclusion filter allows to select which of the parameters are not to be replaced by the overriding expressions, therefore keeping their original values while all other parameters will evaluate with the values set from the last loaded parameter file.
Guide Geometry¶
Double Sided
Visualize the lattice geometry with two distinctive colors per triangle, i.e. front faces and back faces drawn separately. The Outer Fatness of each individual lattice is used as an offset for drawing both front and back faces.
Front colorFrontr colorFrontg colorFrontb
Color used to draw the front facing side.
Back colorBackr colorBackg colorBackb
Color used to draw the back facing side.