Modify Bindings operator

The Modify Bindings operator allows you to modify the properties of existing particle bindings.

Only bindings attached to particles influenced by the operator will be affected.


Modify Bindings Rollout

Filter

  • Affect torn bindings: controls whether bindings that have already been torn will be affected.

  • Affect by ID: controls whether only bindings with a matching ID will be affected.

  • ID: the target binding ID to match.

  • Equal: bindings with an ID that is equal to the target ID will be considered matches.

  • Not Equal: bindings with an ID that is not equal to the target ID will be considered matches.

Scalar Properties

Scalar properties are binding properties defined by a single numerical value.

Property
  • Length: the scalar property being modified will be the binding’s rest length.

  • Stiffness: the scalar property being modified will be the binding’s stiffness.

  • Both: both length and stiffness will be simultaneously modified.

Operation
  • None: does not modify scalar properties of bindings.

  • Set: changes the scalar property to the specified value.

  • Set to current: changes the scalar property to the current value.

  • Multiply current: multiplies the scalar property by the specified value.

  • Multiply original by texmap: sets the scalar property to its original value, multiplied by the spinner value, interpolated with the texmap mono value.

  • Multiply original: sets the scalar property to its original value, multiplied by the spinner value.

  • Min: sets the scalar property to the specified value, if the scalar property is greater than the specified value.

  • Max: sets the scalar property to the specified value, if the scalar property is less than the specified value.

  • Reset to original: resets the scalar property to its original value at the time the binding was first created.

  • Set to current: changes the rest length value to whatever the current distance between the particles is.

The equation for the “multiply by texmap” option is as follows: scalar = origValue * (1 - texmapMonoValue) + origValue * (texmapMonoValue).

Values

While cloth bindings are split into different types (stretch/shear/bend/volume), particle bindings are all considered stretch bindings.

  • Stretch/Shear/Bend/Volume enable: enables modifications for each type of binding.

  • Stretch/Shear/Bend/Volume value: the specified scalar modifier for each type of binding.

  • Stretch/Shear/Bend/Volume texmap: the texmap used in “multiply by temxap” mode for each type of binding.

  • Variation %: the per-particle percentage of variation to apply.
  • Interpolate: the amount to interpolate particle binding scalar modifications from their previous value to the new value.

In order to animate particle binding scalar values changing to a particular value over time, set the operator’s timing to “continuous” and set the interpolation value to something less than 1. Smaller interpolation values will result in slower interpolation speeds.

Tearing Ability

Tearing ability must have previously been enabled on bindings at the time of their creation for these settings to take effect.

  • Don’t change: binding tearing ability will not be changed.

  • Enable: bindings will be flagged as tearable.

  • Disable: bindings will be flagged as un-tearable.

Uniqueness

  • Seed: the seed value for all varied parameters.

Modify Bindings [Cloth] Rollout

Tear weakness

These values allow you to directly adjust binding particle tear weakness values.

Operation
  • None: does not modify tear weakness properties of particles.

  • Set original: changes the tear weakness property to the specified value.

  • Multiply current: multiplies the tear weakness property by the specified value.

  • Min: sets the tear weakness property to the specified value, if the tear weakness property is greater than the specified value.

  • Max: sets the tear weakness property to the specified value, if the tear weakness property is less than the specified value.

  • Reset to original: resets the tear weakness property to its original value.

Values
  • Weakness: The value to use in the tear weakness modification operation.

  • Variation %: the per-particle percentage of variation to apply.
  • Interpolate: the amount to interpolate tear weakness modifications from their previous value to the new value.

In order to animate binding particle tear weakness values changing to a particular value over time, set the operator’s timing to “continuous” and set the interpolation value to something less than 1. Smaller interpolation values will result in slower interpolation speeds.

Inflation Forces

Inflation applies forces along cloth vertex normals during the simulation.

  • Inflation: the strength of the overall inflation force, per particle.

  • Inflation texmap: a texmap that acts as a multiplier on the inflation force value.

  • Float: an artificial force added to the inflation force, in the direction of the world up axis.

  • Float texmap: a texmap that acts as a multiplier on the float force value.

  • Event age ease-in: the strength of the inflation force will be interpolated from 0 to 1 over this many frames.

Increasing the value of “avent age ease-in” allows you to inflate cloth more gradually.

  • Inflate torn cloth: controls whether cloth with torn bindings will inflate.

  • Inflate torn verts: controls whether cloth particles that are directly connected to torn bindings will be inflated.

  • Normalize force: adjusts inflation strength by local face areas.

If the amount of inflation force applied to each particle controlling a cloth mesh is equal, cloth meshes with asymmetrical topology will inflate in a lop-sided manner. This is because areas of the cloth with a dense number of vertices will receive more overall force than areas with a sparse numbers of vertices. “Normalize force” prevents this from occurring, by adjusting local force values to compensate for topology density.

  • Max tear thresh: If the ratio of torn-to-untorn vertices in a cloth mesh is greater than this value, the cloth will no longer be inflated.

To simulate air escaping from a torn cloth mesh (which would prevent inflation), adjust the “max tear thresh” to whatever value gives the best result.

  • Tear force adjust: controls the affect tears will have on inflation force strength. The lower this value, the less of an affect tears will have on the amount of inflation force applied.

The greater the number of overall tears in a cloth mesh, and the greater the “tear force adjust” value, the less of an effect the inflation force will have on vertices. This is an additional way to help simulate air escaping from a torn cloth mesh.

  • Display inflation forces: draws inflation force vectors in the viewport.

Aerodynamic Forces

Aerodynamic forces are calculated using a thin-foil model of cloth faces. Relative cloth vertex velocities are calculated based on per-step force deltas, and then used to compute lift and drag forces for each cloth vertex.

Lift and drag force multipliers should generally be kept very small.

  • Enable aerodynamic forces: controls whether lift/drag forces will be calculated.

  • Lift: the lift force multiplier.

  • Drag: the drag force multiplier.