Issue 286 in alembic: Zero-length vertex normals on closed shell volumes

[ale...@googlecode.com]

Status: New
Owner: ----
Labels: Type-Defect FoundBy-Community

New issue 286 by shappysf...@gmail.com: Zero-length vertex normals on
closed shell volumes
http://code.google.com/p/alembic/issues/detail?id=286

What steps will reproduce the problem?
1. Export a plane and then a sphere from Maya
2. Test the vertex normals (we imported into Houdini and Katana and then
shaded the model displaying the vertex normals to see which geo is "bad")
3. The closed surfaces have bad vertext normals

What is the expected output? What do you see instead?
Valid vertex normals.

What version of the product are you using? On what operating system?
CentOS 5.4, Maya 2012.5sp1, Alembic 1.0.5

Please provide any additional information below.

Here's the export options that were used:

AbcExport options={'jobArg': u'-root sphere -frameRange 1 1 -attr
identifier -attr sharedSourceFile -attr userSourceFile -attr uvs -attr vn
-uvWrite -stripNamespaces -file /tmp/sphere.abc', 'verbose': True}

[ale...@googlecode.com]

Comment #1 on issue 286 by miller.lucas: Zero-length vertex normals on

closed shell volumes
http://code.google.com/p/alembic/issues/detail?id=286

Since the normals haven't changed from the Maya default, no normals are
written to the polymesh. It's not that they are written out as
zero-length, they aren't written out at all, the normals property isn't
valid., i.e. IPolyMeshSchema::getNormalsParam().isValid() returns false.

[ale...@googlecode.com]

Updates:
Status: Resolved

Comment #2 on issue 286 by miller.lucas: Zero-length vertex normals on

closed shell volumes
http://code.google.com/p/alembic/issues/detail?id=286

(No comment was entered for this change.)

[ale...@googlecode.com]

Comment #3 on issue 286 by miller.lucas: Zero-length vertex normals on

closed shell volumes
http://code.google.com/p/alembic/issues/detail?id=286

One thing to note if you are comparing normals being written on a plane vs
not being written for spheres:

We needed to write out normals if any of the edges turned out to be a hard
edge.

http://code.google.com/p/alembic/issues/detail?id=211