Define intersections

Intersectors are instances of geometry that cause strands to be cut off, preventing them from growing any further. When a strand hits an intersector, the strand keeps the same number of CVs, but the length is clipped to the point where it hits the intersector.

This is often used for character animation of both fur and clothes; for example, to prevent the hair strands from poking through the clothes.

Intersectors are treated as subdivision surfaces internally.

Note

Intersectors only work when the Fur node is locked. They don't work on an unlocked groom. Refer to Lock your groom for details.

Creating intersectors

To create an intersector:

  1. Create your groom and save your project.

  2. Create the geometry to use as an intersector.

  3. Select the intersector and the FurSetNode.

  4. From the Wig menu, in the Animation section, select Deform > Add Intersector.

    The geometry now acts as an intersector for the FurSetNode. As you animate the scene, any time the intersector hits a strand, it clips the strand length to the contact point.

  5. Set the intersector options in the wmWigFurNode attributes, under Collision > Intersectors.

Refer to the Fur node atttributes for details.

The most important attribute is the Cache Mode. This controls how Wig caches the strand intersections across timeline frames. The options are:

  • Live Intersect Only: Wig only applies the intersections from the current frame. When you move to the next frame, the intersections reset (all hairs return to their original length).
  • Live Intersect and Collect Cache: Wig collects and caches the intersections from the current frame.
  • Apply Cache Only: Wig ignores the intersectors in the current frame and only applies the cached intersection data.
  • Live Intersect and Apply Cache: Wig applies the cached intersection data and also calculates intersections for the current frame.

You can also set the minimum and maximum length the strands can be set to by the intersection, and which strands can be affected: you can turn off intersections for deforming or non-deforming strands, or for strands that can or cannot re-root.

Clearing intersectors

To clear intersectors:

  1. Select the FurSetNode.

  2. From the Wig menu, in the Animation section, select Deform > Clear Intersectors.

The geometry no longer acts as an intersector.

Warning

Cached intersection data still applies until you flush the cache.