Voronoi Fracture operator

The Voronoi Fracture operator allows you to fracture particle meshes into convex chunks.


Voronoi Rollout

Points

  • Points: the number of points used to create fractures. Roughly the number of resulting fracture meshes, depending on the location of the point cloud.

  • Variation %: the per-particle percentage of variation to apply.
  • Relative to particle volume: controls whether the number of points is relative to the volume of the input shape mesh.

  • Min/Max: the min/max volume values used to create the volume-based point multiplier.

Particle Filter

  • Enable filtering: enables particle filtering.

  • Min volume: particles with a volume smaller than this value will not be fractured.

  • Max volume: particles with a volume larger than this value will not be fractured.

** Min velocity**: particles with a velocity below this value will not be fractured.

** Min impulse**: particles with a PhysX collision impulse below this value will not be fractured.

Fracture Cull

  • Enable culling: enables fracture culling.

  • Min volume: fracture meshes with a volume below this value will be deleted.

  • Min radius: fracture meshes with a radius below this value will be deleted.

Fracture Result

  • New particle per fracture: fracture meshes will be turned into new particles.

  • Center Pivots: moves the fractured shape mesh particle offset to its center.

  • New element per fracture: fracture meshes will be combined as new elements in the particle’s shape mesh, replacing the original mesh.

Performance

  • Max fractures per frame: the maximum number of voronoi fractures to compute, per frame.

Uniqueness

  • Seed: the seed value for all varied parameters.

  • Seed by time: the seed value will be incremented with the current time in ticks.

Point Cloud Rollout

Voronoi point type

  • Random on shape surface: point cloud points will be generated at random locations on particle mesh surfaces.

  • On shape surface by tex: point cloud points will be generated on particle mesh surfaces, based on an input texture map.

  • Cloud: point cloud points will be generated at random locations in space.

Surface points

  • Random offset: the amount of random offset to apply to point cloud point positions, along surface normals

  • Texmap: the input texture map to use for particle positions. The sampled intensity will be used as a probability value to determine valid particle locations.

  • Tries: the number of times the texture sampler will try to find a valid particle location before discarding the point cloud point.

Point Cloud Points

  • Sphere/Box: the bounding shape of the point cloud.

  • Relative to particle bounds: the size of the bounding shape will be relative to the particle’s shape size.

  • Scale X/Y/Z: per-axis scale multipliers for the bounding shape.

  • Scale Mult: a global scale multiplier for the bounding shape.

  • Variation %: the per-particle percentage of variation to apply.

Point Cloud Center

  • Particle: the center of the point cloud will be the particle’s position in space.

  • Shape center: the center of the point cloud will be the center of the particle’s shape mesh.

  • Random in shape bounds: the center of the point cloud will be a random point within the particle’s shape mesh bounding box.

  • Random on shape surface: the center of the point cloud will be a random point on the particle’s shape mesh surface.

  • Random points on object: the center of the point cloud will be a random point on an input object’s surface.

  • At PhysX contact points: the center of the point cloud will be at a PhysX contact points on the particle’s rigidbody hull.

  • Input object list: input objects to use for point cloud positioning.

  • Simulation groups: controls which PhysX collision simulation groups will be candidates for point clouds.

Slice plane normals

  • Scale X/Y/Z: the amount of scaling to add to voronoi cell walls, along each axis. Adjusting these values will stretch the overall shape of the resulting voronoi cells.

  • Show cloud points: displays point cloud points in the viewport.

Uniqueness

  • Seed: the seed value for all varied parameters.

  • Seed by time: the seed value will be incremented with the current time in ticks.

Fractures Rollout

UVs

  • Generate UVs: controls whether UVW coordinates will be preserved on fractures.

Holes

  • Cap holes: controls whether slices will be capped with new faces.
Material
  • Override cap MatID: controls whether cap faces will be given a material ID override.

  • ID: the cap face material ID value.

UVs
  • Generate cap UVs: controls whether UVW coordinates will be generated on new cap faces.

  • Normalize: controls whether cap UVW coordinates will be normalized.

  • Size: the size of the cap face UVW coordinates.

Selection
  • Select cap faces: controls whether new cap faces will be flagged for selection.
Smoothing Groups
  • Smooth cap faces: controls whether new cap faces will be assigned a smoothing group.

When “smooth cap faces” is enabled, the slice algorithm will attempt to assign a smoothing group to cap faces not already assigned to any of the sliced faces around the cap perimeter. If all possible smoothing groups are already used by the sliced faces around the cap perimeter, a smoothing group of 1 will be assigned instead. When “smooth cap faces” is disabled, a smoothing group of 0 will be assigned to cap faces.

Optimize

  • Optimize slice borders: controls whether slice borders will be optimized, removing things like extraneous vertices along parallel edges.

Motion Rollout

Motion

  • Particles move outwards: controls whether forces will be applied to fracture particles.

  • Multiplier: the strength of the fracture force to apply to new particles, in the direction of the original particle’s position to the new particle’s position.

  • Inherit %: the amount of velocity to inherit from the original particle.

  • Variation %: the per-particle percentage of variation to apply.
  • Divergence: the degrees of divergence to apply to fracture forces.

Uniqueness

  • Seed: the seed value for all varied parameters.