Hair Physics (New for v1.24)

In the Auto Setup 1.24 update, prior physics issues were fixed. Few enhancements were made towards Chaos physics configuration and vertex weight-mapping, which includes a more accurate conversion from CC/IC texture weight map to UE vertex weight map (max distance scale value is set to 15 instead of 100 so the physics calculation is more subdued). Chaos physics configuration is optimized with a set of default values to create the best possible physics calculation. With these improvements, hair now moves more naturally without destroying its intended style.

Weight Map Texture Converted to Vertex Weight Map

Hair physics comparison

Commence the following steps for Auto Setup 1.24 results

  1. Adjust the size of the collision shapes on your character’s head and shoulders.
  2. Remove weight paint on unwanted areas and smooth out the weights with the smooth tool.
  3. Make Chaos physics configuration adjustments (Please watch the video to see corresponding results for each configuration).
    • Collision Thickness (0): Thickness of collision shape, larger the number the more distance away from the colliders.
    • Gravity Scale (0.3): Amount of gravity pull.
    • Anim Drive Stiffness (0.5): Put more stiffness in the calculation, which helps retain its intended style.
    • Anim Drive Damping (0.5): More damping and less shaky movement.
    • Subdivision Count (3 or above): calculate physics with subdivision to avoid low-poly edges.

Add a mask and assign it to a specific configuration (in this case, Anim Drive Stiffness)

  1. Create a new mask and set the target to Anim Drive Stiffness.
  2. Enable cloth painting mode.
  3. Paint the tip of the hair to paint value 100 (vertex color white) and keep the remaining as paint value 0 (vertex color pink).
  4. Do a simple smooth with the smooth tool.
  5. Exit cloth painting mode.
  6. Go to Chaos physics configuration and under Animation Properties, you can find Anim Drive Stiffness. Paint values range from 0 to 100 with 0 for the root of the hair and 100 for the tip of the hair. You should keep the hair root stiffer and the hair tip softer.