Add an option to disable Alembic vertex interpolation.
Bump subversion from 5 to 6.
Alembic stores mesh samples at specific time keys; when a frame in
Blender maps to a timecode between two samples, Blender will interpolate
the mesh vertex positions. This interpolation only happens when the mesh
has a constant topology, but sometimes this was not detected properly
when the vertices change order, but the number of mesh elements remains
the same. This would result in a mesh with jumbled up vertices (T71981).
With this patch, users have the ability to disable vertex interpolation.
An alternative would be to have better detection of topology changes,
but that that'll cause a considerable slowdown.
Maniphest Tasks: T71981
Differential Revision: https://developer.blender.org/D9041
This commit only moves code into the `blender::io::alembic` namespace,
it does not move `static` functions into an anonymous namespace.
No functional changes.
This was caused by a side-effect of our exporting code's memory
management (Alembic considers data "written" and "final" when its C++
objects go out of scope) in combination with my change in
rB65574463fa2d. I removed an "only export UVs on the first frame" clause
because it was unclear why this restriction was there. As it turns out,
it breaks the export of the 2nd and subsequent UV maps on an animated
mesh. Effectively, on every frame the Alembic library thought we want to
create a new UV map, instead of continuing to write a new frame of data
to the existing one.
This is resolved by keeping a reference to the C++ objects for the UV
maps in memory while the exporter is running.
Even though {T76514} is caused by invalid geometry, and thus technically
constitutes a bug in the software that created the Alembic file, I would
like Blender not to crash on importing such a file.
The error in the Alembic file consists of invalid mesh loops, where
consecutive loops refer to the same vertex. The `BKE_mesh_validate()`
can actually correct these errors, so this commit focuses on two things:
- Letting Blender survive the situation until the mesh is loaded, and
- Detecting the error so that `BKE_mesh_validate()` can be called only
when necessary. This ensures there is only a minimal impact on
performance when loading actually valid data.
Differential Revision: https://developer.blender.org/D7703
Reviewed By: JacquesLucke
This moves the `alembic`, `avi`, `collada`, and `usd` modules into a common
`io` directory.
This also cleans up some `#include "../../{somedir}/{somefile}.h"` by
adding `../../io/{somedir}` to `CMakeLists.txt` and then just using
`#include "{somefile}.h"`.
No functional changes.
