Alembic: remove support for HDF5 archive format

Alembic is not a single file format, it can be stored in two different
ways: Ogawa and HDF5. Ogawa replaced HDF5 and is smaller and much faster
(4-25x) to read ([source](http://exocortex.com/blog/alembic_is_about_to_get_really_fast)).

As long as Blender has had Alembic support, it has never supported the
HDF5 format in any release. There is a build option `WITH_ALEMBIC_HDF5`
that can be used to enable HDF5 support in your own build. This commit
removes this build option and the code that it manages.

In the years that I have been maintainer of Blender's Alembic code, I
only remember getting a request to support HDF5 once, and that was to
support very old software that has likely since then been updated to
support Ogawa. Ubuntu and Fedora also seem to bundle Blender without
HDF5 support.

This decision was discussed on
[DevTalk](https://devtalk.blender.org/t/alembic-hdf5-support-completely-remove)
where someone also mentioned that there is a tool available that can
convert HDF5 files to the Ogawa format.

1 files changed, 0 insertions, 7 deletions

diff --git a/source/blender/io/alembic/ABC_alembic.h b/source/blender/io/alembic/ABC_alembic.h
index ccc53c589fb..ba430752b29 100644
--- a/source/blender/io/alembic/ABC_alembic.h
+++ b/source/blender/io/alembic/ABC_alembic.h
@@ -35,11 +35,6 @@ struct bContext;
 
 typedef struct AbcArchiveHandle AbcArchiveHandle;
 
-enum {
-  ABC_ARCHIVE_OGAWA = 0,
-  ABC_ARCHIVE_HDF5 = 1,
-};
-
 int ABC_get_version(void);
 
 struct AlembicExportParams {
@@ -68,8 +63,6 @@ struct AlembicExportParams {
   bool export_hair;
   bool export_particles;
 
-  unsigned int compression_type : 1;
-
   /* See MOD_TRIANGULATE_NGON_xxx and MOD_TRIANGULATE_QUAD_xxx
    * in DNA_modifier_types.h */
   int quad_method;