Procedural Hair

November 24, 2022

Present:

• Andy Goralczyk
• Dalai Felinto
• Daniel Bystedt
• Jacques Lucke
• Lukas Tonne

The topics are in order of priority (from higher to lower):

• Distribute child splines on faces
• Hair info
• Clump splines
• Hair frizz
• Curl hair
• Smooth hair
• Braids
• Push hair outside surface
• Rotate hair
• Bend hair
• Straighten hair
• Shrinkwrap hair
• Interpolate shape

Feedback:

• Distribute child curves on faces
  • This is the basic interpolation needed for working with parent/child hair workflow.
• Hair info
  • Should be a node group if possible, before becoming a built-in node
• Clump splines
  • Parting should be doable via attributes within a data-set.
  • The clump criteria (e.g., distance) should be an option for the node.
  • Geodesic distance node would help, ahtough slow
• Hair frizz
  • Keeping the distance between segments is needed regardless.
    • It can be one of the building blocks for the hair frizz group.
• Curl hair
  • The frequency, amplitude and length should be inputs that can be mapped.
  • The total length of the curly hair is important in some cases (to preserve the hair length).
• Smooth hair
  • It doesn't try to align the hair tip with the surface.
  • Preserve the overall length or;
  • Lock the being/end of the curves.
  • Use case/example:
    • If you have a lot of frizz, Daniel would randomly select hair and smooth them out, so it gets a less uniform look.
    • It helps for final tweaks without having to do changes on the begin of a node-tree (before the frizz is applied).
• Braids
  • Braids and corn rows can use the same system.
• Push hair outside surface
  • This is one of the most complicated and important topics.
  • This can be computational expensive.
  • A generic solution may be tricky, but a simple system may be possible for some use cases.
• Rotate hair
  • Spin the hair around the root around the surface normal.
  • Useful to get random overlaps.
• Bend hair
  • The simple case is to bend long hair tips.
  • Nice for moustaches (not french mustaches).
  • For long hair the root point is not relevant.
  • It may be better to pick a few of the last control points, but it is also dependent of the control point density.
• Shrinkwrap hair
  • Useful for some animals, where the hair gets really close to the legs.
• Interpolate shape
  • Useful for animating art-directed hair poses.
• Straighten hair
  • Same as the puff brush.