Voronoi Fracture Points geometry node

Given an object and points of impact on the object, this SOP generates a set of points that can be used as input to the Voronoi Fracture SOP to simulate fracturing the object from those impacts.

On this page	Inputs Parameters Surface Interior Exterior
Since	11.0

The Voronoi Fracture Points SOP takes two primary inputs: the polygonal mesh upon which to generate fracture points, and a set of points which represent “impacts” on the mesh. These impact points can be generated a number of ways, such as through the Add SOP or by scattering points on the surface itself or a separate object.

This SOP works by generating an impact volume from metaballs copied to each impact point. The second input can also accept metaball primitives directly, which will be merged with any copied metaballs to form the impact volume. This volume is then used to divide the input object into three regions.

The Surface region is the surface of the object where it intersects the impact volume. The Interior region is the intersection of a volume representation of the object and the impact volume. The Exterior region is the volume of the object that is outside the impact volume.

In the following cross-section diagram of a box with a single impact point at the end, the purple wireframe represents the impact volume, yellow indicates the surface region, red the interior region, and blue the exterior region.

Each region has parameters that control the density of points generated within it, and how clustering should be applied by a subsequent Voronoi Fracture SOP. A point group is also created for the points generated in each region.

This SOP serves as a key component in Dynamic Fracturing in DOPs.

Note

This node creates a “cluster” attribute on the output points that will only have an effect in fracturing if the Cluster Pieces parameter is enabled on the Voronoi Fracture SOP.

Inputs ¶

Geometry for Impact

The polygonal geometry around which to generate the fracture points.

Impact Points and Metaballs

Input points, where each point represents an “impact” on the object, and metaballs which are merged to form an impact volume.

Optional SDF For Depth Sampling

An optional SDF Volume of the object, usually created by IsoOffset, used internally in several volume-based operations to generate points in the different volume regions. If not connected, a default one will be created.

Parameters ¶

Impact Radius

The radius of the metaball to be copied to each impact point.

Tip

Each metaball can be transformed by the usual copying attributes on the impact points.

Snap Points to Object

Snap each impact point to the object before copying.

Compute Number of Points

Calculate the number of points to scatter in each region based on its surface area.

Points Per Area

The number of points per unit of surface area. This can be scaled by the Point Density parameter for each region.

Number of Points

The number of points to generate.

Per Impact

Whether the Number of Points parameter specifies the total number of generated points or the number of generated points for each impact point.

Volume Resolution

The resolution of the volume representations of the impact metaballs and the object.

Random Seed

The random seed for point scattering.

Visualize Points

Visualize the generated points. The colors for each region are as follows: yellow/surface, red/interior, blue/exterior.

Surface ¶

Point Density

The density of point generation for this region. If Compute Number Of Points is enabled, this parameter is a multiplier of the Points Per Area value. If an explicit Number of Points value is specified, this parameter determines the proportion of those points allocated to this region.

Surface Offset

The amount to offset the generated points from the object surface.

Radius Scale

The amount to scale the impact radius before calculating the surface region.

Clustering

Use Fracture Settings

Create a cluster attribute value of zero for points in this region, allowing a subsequent Voronoi Fracture SOP to override with its own values. Use the parameters on the Voronoi Fracture SOP to control the size of the clustered pieces.

Disabled

Create a unique cluster attribute value for each point in this region, disabling clustering for every fractured piece subsequently generated.

Single Piece

Create the same cluster value for all points in this region, causing all fractured pieces subsequently generated to be clustered together as a single piece.

Interior ¶

Point Density

Clustering

Use Fracture Settings

Disabled

Create a unique cluster attribute value for each point in this region, disabling clustering for every fractured piece subsequently generated.

Single Piece

Create the same cluster value for all points in this region, causing all fractured pieces subsequently generated to be clustered together as a single piece.

Exterior ¶

Point Density

Scatter Location

At Impact

Scatter points at the boundary of the Interior and Exterior regions.

Exterior Volume

Scatter points throughout the exterior volume.

Both

Scatter points at both of the above locations.

Impact Offset

The offset of the Interior/Exterior boundary when scattering using the At Impact or Both setting above.

Clustering

Use Fracture Settings

Disabled

Create a unique cluster attribute value for each point in this region, disabling clustering for every fractured piece subsequently generated.

Single Piece

Create the same cluster value for all points in this region, causing all fractured pieces subsequently generated to be clustered together as a single piece.

Inputs ¶

Parameters ¶

Surface ¶

Interior ¶

Exterior ¶

Geometry nodes