Make hair collide

 
 
 

You can make hairs in a hair system collide with themselves and with other objects. As an alternative or in addition to setting objects to collide with hair, you can use hair constraints that act as implicit collision objects. These can be helpful if hairs are getting stuck in surfaces, since these implicit collision objects are volumes, not shells. Also, you can set the collision object constraints to affect specific hair curves, whereas Make Collide and the other collision options affect the entire hair system. The combination of collision constraints and geometry collisions can provide robust collision, while at the same time preserving fidelity of the collide object surface. For more information about the Collide Sphere and Collide Cube implicit collision objects, see Set up hair constraints.

Note

Iterations (Dynamics) increases the number of collision tests. A setting of 8 does twice as many as 4. This can improve the results of collisions in some cases, but will also slow down the simulation calculation. If you increase Iterations you need to lower Stiffness to compensate.

Fine tune collisions

If hairs are getting stuck in colliding surfaces, consider the following:

To make hair collide with the ground

  1. In the hair system’s Attribute Editor, turn on Collide Ground in the Collisions section. The “Ground” is the ground plane (or the grid).
  2. Optionally, adjust the Ground Height value, which is relative to the ground plane.

To make hair collide with objects

  1. Select the hair system. (Window > Outliner)
  2. Shift-click to select the object or surface you want the hair to collide with.
  3. Select Hair > Make Collide. A geoConnector node is added to your collision object.

    If your collisions are not working, make sure Collide is turned on in the hair system Attribute Editor.

    If your hair is penetrating the collision object, then you can try the following:

    • Increase the Tessellation value in the collision object’s geoConnector node.
    • Increase the Collide Over Sample value in the Collisions section of the hairSystemShape.

To make hairs collide with themselves

  1. In the hair system’s Attribute Editor, turn on Self Collide in the Collisions section.
  2. Adjust collision settings, including the Collide Width Offset.