Houdini 20.0 Nodes Geometry nodes

Ragdoll Collision Shapes 2.0 geometry node

Creates collision shapes for a KineFX skeleton to be used in a ragdoll RBD simulation.

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Since 20.0

This node provides an interactive way of creating and modifying collision shapes for a KineFX skeleton for the purpose of running it through a ragdoll RBD simulation.

Parameters

Group

The joints to build collision shapes for. Joints outside of this group will not be configurable.

Rest Pose Attribute

Use the specified point rest transform attribute to set the skeleton to its rest state before creating the collision shapes.

Output Group

When turned on, outputs a point group on the skeleton that holds all the joints that have a corresponding collision shape.

Group Name

The name of the point group to output.

This parameter is only available when Output Group is turned on.

Clear Overrides

Clear all manual overrides added via the node’s state.

Generate Shapes

Generate Shapes Group

The joints to build collision shapes for via the Generate Convex Hulls from Skin Geometry and Generate Basic Shapes options. If any of these two options are enabled, joints outside of this group become unconfigurable.

If Generate Convex Hulls from Skin Geometry is enabled, joints outside of this group will have their corresponding collision shape, as generated by the Generate Convex Hulls from Skin Geometry option, merged together with the shape of the first found parent joint. This is useful in scenarios when, for example, you want to treat the hand of a humanoid character as a single shape and not have a separate shape per finger segment.

Generate Convex Hulls from Skin Geometry

Generate collision shapes for all joints in the input skeleton that have an influence on the deformation of the Rest Geometry, i.e. have been skinned to the Rest Geometry. The resulting shapes are built using the convex hull algorithm, see Shrinkwrap SOP. This option requires a Rest Geometry input with a valid boneCapture point attribute in order for it to work correctly.

Note

The resulting collision shapes are built from the Rest Geometry and are not transformed based on the Rest Pose Attribute of the skeleton. The skeleton is used here only to slice up the skin by capture regions. This means that if the provided Rest Pose Attribute is different than the Capture Pose of the skeleton, the resulting collision shapes and the Rest Pose Attribute pose will not match up, which will cause issues down the line.

If your Rest Pose Attribute pose is different than the skeleton’s Capture Pose, you can use a Joint Deform SOP to deform the Rest Geometry upstream of this SOP, in order to get it to match the Rest Pose Attribute of the skeleton, or you can deform the resulting collision shapes downstream of this SOP, in order to get them to match the Rest Pose Attribute of the skeleton.

Generate Basic Shapes

Generate basic collision shapes for all joints in the input skeleton. This method attempts to position and scale the newly created basic shapes using the skeleton’s hierarchy.

Basic Shape

If Generate Basic Shapes is enabled, choose which basic shape you want to use for the generation.

Guide Geometry

Display Guides At Rest Transform

When turned on, display the guide geometries at rest transform.

Tip

Turning this off allows you to visualize the shape intersections that may appear throughout the input animation.

Display Collision Shapes

When turned on, display the guide geometry for the collision shapes in the viewport.

Display Intersections

When turned on, guide geometry will be drawn showing the intersections between collision shapes in bright red. These intersections are usually causes of instability when trying to run the solver.

Inputs

Skeleton

The input skeleton to be processed.

Collision Shapes

Custom shapes to assign as collisions. These shapes are expected to have a valid name primitive attribute and be in PackedGeometry format.

Rest Geometry

The character’s skin, at rest pose, for procedurally generating collision shapes using the capture data.

See Generate Convex Hulls from Skin Geometry for more details.

Outputs

Skeleton

The input skeleton unmodified.

If Output Group is enabled, a point group will be created on the skeleton.

Collision Shapes

The collision shape geometry.

See also

Geometry nodes