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.

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.