Emitting Hair from Subdivision Surfaces

 
 
 

If you created hair on a polygon mesh that has a geometry-approximated subdivision surface, you can have the guide hairs emitted from this surface instead of the outer "hull." The positions of the guide hairs on the subdivision surface correspond to the same point location on the hull.

When you apply a weight map or texture map to a subdivision surface (see Connecting Maps to Render Hair Parameters), the maps are evaluated on its surface at the guide hair locations, as with other polygon or NURBS objects.

TipIf you want to use the hair-emitting subdivision surface as an obstacle for its own hair, see Tips for Setting Up Obstacles for Hair.

To emit hair from a subdivision surface

  1. Select a polygon mesh and create a geometry approximation property for it by choosing GetPropertyGeometry Approximation.

    For more information about subdivision surfaces, see Subdividing with Geometry Approximation [Polygon Modeling].

  2. In the object's Geometry Approximation property editor, click the Polygon Mesh tab and set the SubdivisionOGL and/or Render Level.

       

    Head with geometry-approximated subdivision levels of 2.

  3. Apply hair to the polygon mesh, or to selected polygons or clusters on the mesh (choose Create Hair from Selection from the Hair toolbar).

  4. In the Hair Generator Operator property page (appears at the bottom of the Hair property editor), set the level of the Emitter Subd Level slider.

For example, if you want the hairs to be directly upon the subdivision surface, set the level value here to match the number of subdivisions of the geometry approximation. Notice that the number of guide hairs does not change.

NoteWhen you change the subdivision level, it is considered a topology change and may slightly modify the shape of the guide hairs.
 

Hair is emitted from the hull at a level of 0.

Hair is emitted directly from the subdivision surface at a level of 2. Notice how the hair comes out of the head surface itself, not the hull.

Tip

From the Geometry Approximation property editor, drag and drop the Render Level (or OGL Level) parameter's animation icon to the Emitter Subd Level parameter's animation icon to create an "equal to" expression. Then whenever you change the Render Level (or OGL Level) value, the hair will be emitted from that same level of subdivision.

For more information, see Creating Expressions.