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Carbon Rigid Body

Type

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Object node (SOP and DOP).

Description

This node defines a rigid body object, its import geometry, and the rigid body parameters.

Attach this node to a merge node together with a Carbon Collider node, then the merge node to a Carbon Simulation to form a simple rigid body simulation scenario.

Rigid body nodes can be attached together by a Carbon Joint constraint, and to a Carbon Cloth using a Carbon Welding constraint.

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Carbon Rigid Bodies.

Parameters

Geometry

Reference Pose

SOP Path refPose

The path to the collision geometry reference pose. Can be either a Geometry node object or a SOP node.

Primitive Group refGroup

Primitive group of the reference geometry that determines which primitive set goes into the collider shape. The whole reference geometry is used per default when this is left empty.

Welding Distance weldingDistance

Threshold used to consolidate the geometry points at near identical positions.

Start Pose

SOP Path startPose

The path to the collision geometry start pose. Can be either a Geometry node object or a SOP node.

Primitive Group startGroup

Primitive group of the start geometry that determines which primitive set goes into the collider shape. The whole start geometry is used per default when this is left empty.

Collision Properties

Inner Fatness innerFatness

Inner collision shape surface thickness. Use 0 for a single sided surface.

See also

Fatness

Outer Fatness outerFatness

Outer collision shape surface thickness.

See also

Fatness

Mass Properties

Mass mass

Mass of the object.

Mass Box Offset tx ty tz

Position offset of the Mass Box.

This points to the center of mass of the rigid body.

Mass Box Rotate rx ry rz

Rotation of the Mass Box.

Represents the inertia axis orientation of the rigid body.

Mass Box Size sizex sizey sizez

Dimensions of the Mass Box extents.

Represents the inertia axis of the rigid body.

Override Mass Box override

Allow changes to the computed values for the mass box parameters.

Removing the override recalculates the massbox properties from the specified sop geometry.

Use Object Transform Axis usetransform

Use the sop geometry transform as the origin of the simulated object to make for an easier authoring of the Mass Properties of this rigid body. If the sop geometry transform does not represent the rigid body’s center of mass and principal axis, then it is best to leave this toggle unchecked.

Collision Material

Animated Material 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

Rigid body’s static friction, between 0 and 1 and must be bigger than Dynamic Friction.

See also

Friction

Dynamic Friction dynamicFriction

Rigid body’s dynamic friction, between 0 and 1 and must be smaller than Static Friction.

See also

Friction

Restitution restitution

Rigid body’s restitution, between 0 and 1. Used during Rigid Body collisions where the resulting collision energy is modulated by the product of each object’s restitution.

Aerodynamics

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.

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

Aerodynamics

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

Aerodynamics

Lift lift

Aerodynamics lift. Lift force coefficient.

Warning

Explicit force, so high values can produce instability.

See also

Aerodynamics

Initial Velocity

Linear Velocity linearVelocity

Initial linear velocity.

Angular Velocity angularVelocity

Initial angular velocity.

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

Show Mass Box showguide

Display the mass box that represents the inertia axis and center of mass of the rigid body.

Additionally displays the original world space frame the geometry has been imported from.

Mass Box colorMassBoxr colorMassBoxg colorMassBoxb

Color used to draw the mass box when Show Mass Box is toggled on.

Show Carbon Mesh bodyshowguide

Display the collision shape generated from the Houdini geometry.

Carbon Mesh colorCarbonMeshr colorCarbonMeshg colorCarbonMeshb

Color used to draw the Carbon shape when Show Carbon Mesh is toggled on.