Carbon Tetra¶
Description¶
This object node defines a tetra simulation object, its import geometry, and the tetra parameters.
Input a tetrahedral mesh into this node, then attach this object node to a merge node together with a Carbon Collider node, then the merge node to a Carbon Simulation node to form a simple simulation scenario.
A Carbon Tetra.
Parameters¶
Activation activation
Enable this object. Use 0 to disable, any other value to enable.
Reference Pose
Animated Geometry geometryAnimated
Enable animated parameters for this section by evaluating and updating the values at every frame.
Note
It’s good practice to leave this toggled off when not using
animated parameters because it impacts performance.
Animated Metrics metricsAnimated
Enable animated reference geometry metrics by evaluating and updating the reference lengths at every frame.
SOP Path refPose
The path to the reference pose geometry. Can be either a Geometry node object or a SOP node.
The reference pose can be animated.
Note
The Carbon Tetra node requires at least a reference pose geometry (or SOP) to be valid.
Primitive Group refGroup
Primitive group of the geometry that determines which primitive set goes into the tetra reference pose shape. The whole geometry is used by default when this is left empty.
Note
Cannot be used in combination with Tetra Group.
Start Pose
SOP Path startPose
The path to the start pose geometry. Can be either a Geometry node object or a SOP node.
The start pose allows the tetra to start the simulation in a different pose than its reference pose.
Note
- When no start pose geometry is specified, the reference pose geometry is also used as the start pose.
- The start pose geometry needs to respect the same topology as the reference pose.
- If there is a
velocitypoint attribute on the Tetra Start Pose geometry, it will automatically be used to inject initial point velocities into the Tetra.
Primitive Group startGroup
Primitive group of the geometry that determines which primitive set goes into the tetra start pose Shape. The whole geometry is used by default when this is left empty.
Goal Pose
If no Reference Pose is set, all Goal Pose parameters are grayed out and cannot be edited.
Animated Goal Pose goalPoseAnimated
Enable animated goal pose geometry by evaluating and updating the position targets at every frame.
SOP Path goalPose
The path to the goal pose geometry. Can be either a Geometry node object or a SOP node.
The goal pose allows the tetra to match the specified pose during the simulation.
The goal pose geometry is usually used animated, or enabled for a short period of time through the Skin strength parameters.
If no SOP Path is set, all Goal Skin parameters are grayed out and cannot be edited.
Note
The goal pose geometry needs to respect the same topology than the one found on the reference pose.
See also
Primitive Group goalGroup
Primitive group of the geometry that determines which primitive set goes into the tetra goal pose shape. The whole geometry is used per default when this is left empty.
Enable goal
Enable/disable the goal posing without having to empty the goal pose SOP path. If disabled, all Goal Skin parameters are grayed out and cannot be edited.
Collision Properties
Tetra Group groupA
Tetra group defining the collision geometry.
Note
- This parameter is optional. If left empty, all tetrahedrons are used for the collision geometry.
- Cannot be used in combination with Primitive Group.
Self Collide selfCollide
Enable self-collision for this tetra against itself.
Animated Density densityAnimated
Enable animated parameters for this section by evaluating and updating the values at every frame.
Note
It’s good practice to leave this toggled off when not using
animated parameters because it impacts performance.
Base Parameters
Density densityBase
Tetra density. Unit in kg/m^3.
Painted Attribute Range
Density densityRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: density
Animated Volume volumeAnimated
Enable animated parameters for this section by evaluating and updating the values at every frame.
Note
It’s good practice to leave this toggled off when not using
animated parameters because it impacts performance.
Base Parameters
Volume Compression volumeCompressionBase
Volume compression, must be strictly greater than 0 and always be smaller than or equal to extension.
Note
Setting both Volume Extension and Volume Compression to 1 guarantees volume preservation.
See also
Volume Extension volumeExtensionBase
Volume extension, must be strictly greater than 0 and always greater than or equal to compression.
Note
Setting both Volume Extension and Volume Compression to 1 guarantees volume preservation.
See also
Painted Attribute Range
Volume Compression volumeCompressionRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: volumeCompression
Volume Extension volumeExtensionRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: volumeExtension
Animated Stretch stretchAnimated
Enable animated parameters for this section by evaluating and updating the values at every frame.
Note
It’s good practice to leave this toggled off when not using
animated parameters because it impacts performance.
Base Parameters
Stretch Stiffness stretchStiffnessBase
Tetra stretch stiffness (mass/time^2).
See also
Stretch Viscosity stretchViscosityBase
Tetra stretch viscosity (dimensionless).
See also
Stretch Compression stretchCompressionBase
Tetra stretch compression, must be strictly greater than 0 and always be smaller than or equal to extension.
See also
Stretch Extension stretchExtensionBase
Tetra stretch extension, must be strictly greater than 0 and always greater than or equal to compression.
See also
Stretch Equilibrium stretchEquilibriumBase
Tetra 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
Goal Skin
If no Goal Pose SOP Path is set or if Goal Pose is disabled, all Goal Skin parameters are grayed out and cannot be edited.
Animated Goal Skin goalSkinAnimated
Enable animated parameters for this section by evaluating and updating the values at every frame.
Note
It’s good practice to leave this toggled off when not using
animated parameters because it impacts performance.
Goal Skin Velocity Limit goalSkinVelocityLimit
The maximum relative velocity between a simulated and animated node.
Base Parameters
Goal Skin Strength goalSkinStrengthBase
The goal skin maximum strength.
See also
Goal Skin Viscosity goalSkinViscosityBase
The goal skin viscosity to cope with fast moving motions. Unit in 1/time.
Viscous behavior between a node and its animation.
Painted Attribute Range
Goal Skin Strength goalSkinStrengthRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: goalSkinStrength
Goal Skin Viscosity goalSkinViscosityRange
The multiplier of the painted point attribute values that add up to the base parameter.
Lower Threshold
Goal Skin Strength goalSkinLowerThreshold
The strength threshold below which a node is not skin constrained. The value for this attribute ranges from 0 to 1, interpolating between the lowest and the highest possible goal skin strength (taking both the base and the painted parameter into account).
See also
Upper Threshold
Goal Skin Strength goalSkinUpperThreshold
The strength threshold above which a skinned node becomes kinematic and animated. The value for this attribute ranges from 0 to 1, interpolating between the lowest and the highest possible goal skin strength (taking both the base and the painted parameter into account).
See also
Animated Viscous Damping viscousDampingAnimated
Enable animated parameters for this section by evaluating and updating the values at every frame.
Note
It’s good practice to leave this toggled off when not using
animated parameters because it impacts performance.
Base Parameters
Viscous Damping viscousDampingBase
Tetra 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
Animated Reducer reducerAnimated
Enable animated parameters for this section by evaluating and updating the values at every frame.
Note
It’s good practice to leave this toggled off when not using
animated parameters because it impacts performance.
Base Parameters
Reducer reducerBase
Tetra velocity reducer. Ranges from 0 to 1, where a value of 0 has no effect and 1 removes 100% of the point velocity.
Painted Attribute Range
Reducer reducerRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: reducer
Animated Friction materialAnimated
Enable animated parameters for this section by evaluating and updating the values at every frame.
Note
It’s good practice to leave this toggled off when not using
animated parameters because it impacts performance.
Static Friction staticFriction
Tetra’s static friction, greater than or equal to 0 and greater than or equal to dynamic friction.
See also
Dynamic Friction dynamicFriction
Tetra’s dynamic friction, greater than or equal to 0 and smaller than or equal to static friction.
See also
Animated Aerodynamics aerodynamicsAnimated
Enable animated parameters for this section by evaluating and updating the values at every frame.
Note
It’s good practice to leave this toggled off when not using
animated parameters because it impacts performance.
Base Parameters
Drag dragBase
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 skinDragBase
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 liftBase
Aerodynamics lift. Lift force coefficient.
Warning
Explicit force, so high values can produce instability.
See also
Painted Attribute Range
Drag dragRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: drag
Skin Drag skinDragRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: skinDrag
Lift liftRange
The multiplier of the painted point attribute values that add up to the base parameter.
Note
Painted point attribute name: lift
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¶
Paint Map
Visualize painted attributes using two base colors and interpolate in between.
Paint Map paintMap
The painted attribute to be displayed.
Zero colorZeror colorZerog colorZerob
Color used to draw a painted value of 0.
One colorOner colorOneg colorOneb
Color used to draw a painted value of 1.
Goal Skin
Visualize the points of the tetra that are fully dynamic, skinned (using a mix of the two others’ color) or kinematic.
See also
Fully Dynamic colorDynamicPointr colorDynamicPointg
colorDynamicPointb
Color used to draw all points that won’t be constrained by the Goal Pose.
Kinematic colorKinematicPointr colorKinematicPointg
colorKinematicPointb
Color used to draw all points completely constrained by the Goal Pose.
Cross Section
Visualize a cross section of the tetra geometry.
Plane Orientation plane
Orientation of the cross section plane.
Plane Offset planeOffset
Drawing offset of the cross section plane in regard to the object’s bounding box center. The value ranges from -1 to 1, where -1 will display no geometry all and 1 will display all geometry within the bounding box of the Tetra.
Display Tetras displayTetras
Enable/disable the visualization of tetrahedrons through the cross section.
Tetra colorTetrar colorTetrag colorTetrab
Color used to draw all tetrahedrons visible through the cross section.
Display Segments displaySegments
Enable/disable the visualization of segments through the cross section.
Segment colorSegmentr colorSegmentg colorSegmentb
Color used to draw all segments visible through the cross section.
Display Points displayPoints
Enable/disable the visualization of points through the cross section.
Point colorPointr colorPointg colorPointb
Color used to draw all points visible through the cross section.
Export¶
Export Velocity velocity
Enable to export point velocities.
Note
If there is a velocity point attribute on the Tetra Start Pose
geometry, it will automatically be used to inject initial point velocities
into the Tetra.
Export Volume Stress volumeStress
Enable to export volume stress physics attribute.
Export Stretch Stress stretchStress
Enable to export stretch stress physics attribute.
Examples¶
$SIMCARBONTOOL_PATH/documentation/_downloads/tetra.hip
$SIMCARBONTOOL_PATH/documentation/_downloads/tetra_sop.hip