Edge Fracture operator

The Edge Fracture operator allows you to slice particle meshes along the sharp edges of their convex hull.


Edge Fracture Rollout

Fracture operation

  • Fracture edges: particle meshes will be fractured along the edges of adjacent faces which form a crease.

  • Fracture corners: particle meshes will be fractured at their corners, where groups of edges share a single vertex.

Fracture Meshes

  • Center pivots: controls whether the pivots of resulting fracture particles will be centered on their mesh.

Edges Rollout

Edge Thresholds

  • Edge angle threshold: the minimum angle between adjacent faces connected to an edge required in order to perform a slice along the edge.

  • Length threshold min: the minimum length an edge must be in order to be fractured.

  • Length threshold max: the maximum length an edge can be in order to be fractured.

  • Mean length % thresh: an edge’s length must not deviate more than this percentage from the average edge length on the mesh, in order to be fractured.

If the average length of an edge on a mesh is 1.0, and a particular edge length is 1.20 and the mean length % thresh is set to 25%, the edge will be fractured because its length is within a 25% deviation from the average length. However, if the particular edge length is 1.30, it will not be fractured because its length is a 30% deviation from the average length. In other words, the smaller this value, the closer an edge’s length must be to the average edge length of the mesh in order to be fractured. Larger values allow for more variation in the lengths of sliceable edges.

Fractures

  • Fractures per edge: for any given detected edge, the number of initial fractures to generate, prior to any further culling operations.

  • Fracture probability: the probability that any given edge which passed all of the edge threshold tests will be fractured.

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

  • Fracture depth: the distance along the negative edge normal the slice plane will be moved. Higher values result in deeper cuts.

  • Variation %: the per-particle percentage of variation to apply.
  • Slice plane divergence: the maximum angle that any given slice plane normal will diverge from the edge normal.

  • MatID filter: when enabled, edges will only be sliced if one or more of their adjacent faces has a material ID matching the specified value.

Uniqueness

  • Seed: the seed value for all varied parameters.

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

Corners Rollout

Corner Thresholds

  • Angle threshold: the maximum cumulative angle between all edges connected to a single vertex, in order for the vertex to be considered a valid corner.

The smaller the angle threshold, the sharper a corner must be in order to be fractured.

Fractures

  • Fractures per corner: for any given detected corner, the number of initial fractures to generate, prior to any further culling operations.

  • Fracture probability: the probability that any given corner which passed all of the corner threshold tests will be fractured.

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

  • Fracture depth: the distance along the negative corner normal the slice plane will be moved. Higher values result in deeper cuts.

  • Variation %: the per-particle percentage of variation to apply.
  • Slice plane divergence: the maximum angle that any given slice plane normal will diverge from the corner normal.

  • MatID filter: when enabled, edges will only be sliced if one or more of their adjacent faces has a material ID matching the specified value.

Uniqueness

  • Seed: the seed value for all varied parameters.

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

Slices Rollout

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.