Position Transfer operator

The Position Transfer operator allows you to transfer particles from one surface to the exact relative location on another surface with the same topology.

The Position Transfer operator can be especially helpful when you want to simulate particles on a static surface, and then transfer their motion to a matching animated surface (ie, an animated character). It is often easier to perform this kind of transfer from static to animated mesh, than to try and perform the initial particle simulation on the animated mesh directly.

For the position transfer to work correctly, the objects in the list must have the same topology and be in the same order in all matching Position Transfer operators.

When transferring data between flows, don’t forget to enable Custom TM channel caching in the source flow.


Transfer properties

  • Transfer position/rotation/scale: controls which relative particle properties to transfer between surfaces.

Operation

  • Save surface location: the operator will save the relative surface location of particles to a custom TM data channel.

  • Load surface location: the operator will load the relative surface location of particles from a custom TM data channel.

  • Channel: the main custom TM data channel where transfer data will be stored.

  • Aux channel: the secondary custom TM data channel where rotation/scale offset data will be stored, if rotation/scale property transfer is enabled.

If both channels are required for the transfer (ie, if you’ve enabled rotation/scale transfer), ensure they are not assigned the same name.

Mode

  • Barycentric Coordinates: saves the transfer data as relative barycentric coordinates of the closest face on the source mesh.

  • Face transform: saves the transfer data as a position relative to a transform constructed from the closest face on the source mesh.

“Barycentric coordinate” mode works best if particles are near the source surface and the source surface is fairly smooth. It does a good job of smoothly interpolating particles between faces on the target mesh, so long as particles are not too far away from the source surface and the surface does not have a lot of hard edges/angles, otherwise it can result in popping artifacts. “Face transform” mode will not smoothly interpolate particles between faces, but does a better job at storing the absolute particle position relative to the source mesh, even if the particles are heavily offset from the source surface.

When transferring rotation/scale data, face transform mode must be used.

Objects

  • Object list: the list of input objects that particles will be transferred to/from.

Sample

  • Sample type: controls which sampler will be used to determine closest-surface proximities for particles.

Interpolation

  • Value: the amount to interpolate particle positions from their previous value to the new value.

  • Variation %: the per-particle percentage of variation to apply.
  • Full interpolation on entry: when a particle’s event age is zero, its interpolation value will be temporarily set to 1.0.

Uniqueness

  • Seed: the seed value for all varied parameters.