Exploding hair when reopening a scene 

 

Problem 

Guides are randomly rotated when opening a previously saved scene.

 

Cause 

This is caused by Maya re-triangulating the deforming faces of the mesh. Ornatrix works with mesh triangles when generating the hair and so it is important that the topology of these triangles on the distribution surface don't change, but sometimes Maya change the triangulation without the user acknowledgement when a scene is reloaded.

Maya has a special Quad Split attribute on mesh shapes which determines how it generates triangles from quads when the mesh deforms. By default, Maya uses Best Shape option for this attribute. This means that it can change the order of the triangles on a quad dynamically during generation. This will cause problems with Ornatrix.

 

Solution 

Ornatrix will attempt to automatically adjust the Quad Split attribute when you assign a shape as a distribution surface for one of its operators. However, if this doesn't happen for some reason you can manually solve this problem by:

  1. Selecting your distribution surface mesh and going to the Attribute Editor
  2. Opening the Mesh Controls group
  3. Changing the Quad Split attribute to Left or Right (anything except Best Shape)

These steps can be used to avoid this problem, but if you already have this problem follow these steps to get the guides back into position:

  1. Selecting your distribution surface mesh and go into vertex mode
  2. Select one vertex and move it. This should get the guides back into position, if not, go to GuidesFromMesh and change the Distribution Type back and forth
  3. Now that the guides are back into position go back to object mode and open the Attribute Editor
  4. Open the Mesh Controls group and turn ON Reuse Triangles. This will ensure that the triangulation will remain the same even if the base mesh is tweaked or deformed, It will also prevent Maya from changing the mesh triangulation while loading a scene.