2019-10-25, Alembic 1.7.12
Thanks to your feedback and numerous pull requests we have several enhancements
and bug fixes.

API:

Use critical section instead of mutex on Windows. (PR220)

ErrorHandler now uses const char * for message instead of std::string for
efficiency gain. (PR221)

Fix incompatibilities with C++17. (PR237)

Add optional DCC FPS hint when calling CreateArchiveWithInfo and
GetArchiveInfo. (PR241)

Maya:

AbcExport: Support writing animated facesets. (PR217)

AbcExport: Support per curve width. (PR239)

AbcExport: When writing sparse data like just the UVs, create an OObject
instead of an OXform.  (PR241)

Utils:

WFOBJConvert: Fix bug where OBJ files with more than one shape would fail to
properly convert UVs and Normals. (PR232)

CMake:

Make it easier to select the python version to build against.  (PR215)

2019-5-16, Alembic 1.7.11
Thanks to your feedback and numerous pull requests we have several enhancements
and bug fixes.

CMake:

Make ILMBase detection compatible with certain older versions. (PR207)

Allow Alembic to build against a custom Python installation. (PR208)

OpenMayaMac.h was removed from the DevKit since Maya 2016. (Issue210)

API:

Fix bug in OSubD where the detection of a partial sample was incorrect.

Maya:

AbcExport: Fix issue where certain user properties were incorrectly being
written as arbGeomParams.  (Issue 209) (PR211)

AbcExport: Fix an issue with acyclic detection because of floating point
inaccuracy. (PR213)

2018-12-5, Alembic 1.7.10
Thanks to your feedback and numerous pull requests we have several enhancements
and bug fixes.

API:

Check to see if the OCompoundProperty already exists before trying to create
a new one. (PR200, Issue 188)

Explicitly include errno.h for compilers that don't bring it in as part of the
other includes.  (Issue 199)

Maya:

Support reading and writing nParticles as I/OPoints.  (PR163)

Houdini:

Update the example SOP to work with Houdini 16.5, support layering,
and take advantage of the Houdini API for faster geometry building. (PR196)

2018-9-7, Alembic 1.7.9
Thanks to your feedback and numerous pull requests we have several enhancements
and bug fixes.

API:

Add memory mapped read support for Ogawa, which is now on by default but
can be toggled off via Alembic::AbcCoreFactory::setOgawaReadStrategy.
Read speed is improved by about 10-25% on Linux and potentially much more on
Windows. (PR 187)

Make getOrders and getKnots const on Alembic::AbcGeom::ICurves. (PR 162)

Remove prefix _ in our include guards to be ISO conformant.  (PR 192 and 194)

Remove some unnecessary null pointer checks before deleting an object. (PR 193)

When "wrapping" an IObject around the ISchemaObject properly copy the IObject
so that the instancing info is copied over as well. (PR 195)

Maya AbcImport/AbcExport:

Update several deprecated Maya API function calls. (PR 173)

Clean up some compiler warnings and add override keyword to a few methods.
(PR 174)

Prevent crash for importing certain invalid NURBS surfaces and add the error
message when the NURBS surface can't be created. (PR 175)

Alembic file translator now resolved in the same way as the AbcImport command.
(PR 176)

Fix per-face shader assignments not merging if the mesh to merge is an
intermediate object.  (PR 177)

Utils:

AbcStitcher:

Fix crash when trying to stitch subd corner sharpness.  ( PR 181 )

CMake:

Use /bigobj flag for Visual Studio 2008/MSVC15.
Use PyAlembic as a target and property name to avoid a naming conflict.
Python binding alembic.so should be alembic.pyd on Windows. ( PR 172 )

Add the msvc14fixes.cpp for the python bindings if using MSVC 14 2015 Update 3.

##-*****************************************************************************

2018-4-30, Alembic 1.7.8
Thanks to your feedback and generous pull requests we have some enhancements.

CMake:

Add ability to specify where to install the Alembic libraries. (PR 165)

Add option to NOT build the library. (PR 166)

Add option to specify where to install the python module. (PR 167)

Add option to specify where to intall the Maya plug-ins. (PR 168)

Utils:

AbcStitcher:  Add verbose flag and try to accomodate stitching sampling with
the same time sampling but with slightly different start times in the same
IArchive. (PR 169)

2018-3-23, Alembic 1.7.7
Thanks to your feedback and pull requests we have a few bug fixes and an
enhancement.

API:

Fix bug where std::weak_ptr was used in AbcCoreLayer instead of
Alembic::Util::weak_ptr.

Add OCurves::Schema::Sample::setPositionWeights to go along with the get.
Expose it in the python bindings.

prman Procedural:

Add two options, -motionbegin and -motionend to explicitly control MotionBlocks.
(PR 160)

##-*****************************************************************************

2018-3-7, Alembic 1.7.6
Thanks to your feedback and pull requests we have a few bug fixes.

API:

Fix memory issue when traversing an AbcCoreLayer hierarchy that also happens to
use heavy instancing. (PR 151)

Work around a pread OSX issue when trying to read data samples over 2 GB, by
reading it in smaller chunks.  (PR 153 and PR 155)

Fix bug in AbcCoreLayer where the replace/prune logic was occurring in the
opposite order of the data layering.  We've adopted the data layering order
style.  (data in the first file specified overrides later files)
(PR 156 and PR 157)

Here is the canonical example order:

sparseAnimatedPoints.abc sparseUVs.abc base.abc

Python:

Work around compiler bug in MSVC14 Update 3 involving boost::python. (PR 154)

prman Procedural:

Support widths on IPoints. (PR 147)

Support visibility on IPolyMesh. (PR 148)

##-*****************************************************************************

2017-12-20, Alembic 1.7.5
Thanks to your feedback we have a bug fix:

API:

Fixed bug where getPropertiesHash and getChildrenHash were returning the wrong
value for AbcCoreLayer archives that are made up of only on file. (PR 143)

##-*****************************************************************************

2017-10-12, Alembic 1.7.4
Thanks to your feedback and pull requests we have a few bug fixes and an
enhancement.

API:

Do not allow scalar properties to match when they have the same data type
but different extents.  This is to avoid a segfault on getValue. (Issue 138)

Add: const AbcA::ObjectWriterPtr getPtr() to OObject.h (PR 141)

Remove an accidental circular include dependency in AbcCoreLayer. (PR 141)

##-*****************************************************************************

2017-8-9, Alembic 1.7.3

Thanks to your feedback we have a bug fix introduced in the previous release.

API:

Fix a bug where a file opened as Ogawa but not Ogawa would be closed twice
causing issues on Windows. (Issue 135)

##-*****************************************************************************

2017-7-21, Alembic 1.7.2

Thanks to your feedback and pull requests we have a few bug fixes and
enhancements.

API:

Fix bug with IFaceSet::getFaceExclusivity (Issue 129)

When reading directly from a file with Ogawa use pread/ReadFile so we don't have to use a file descriptor per stream.  (Issue 124)

Misc:

Propagate HDF5 dependency when doing a static build mentioned in Issue 126. (pull request 128)

Fix up several other minor CMake issues mentioned in Issue 127. (also pull request 128)

Make sure the shared library is given a major/minor version. (based on pull request 125)

##-*****************************************************************************

2017-3-24, Alembic 1.7.1

Thanks to your feedback and pull requests we have a few bug fixes and
enhancements.

API:

Address Issues 110 and 114 make a few member functions const.

Maya AbcExport:

Fix call to isAnimated when writing Nurbs curves.

Tools:

Fix issue 101 which was a crash in abcls by being careful when
printing certain strings.

Rework AbcDiff so it better handles completely different hiearchies,
and only attempts to do diffs on Ogawa files so we can take advantages
of the computed hashes.

Misc:

Add continuous integration to the project via Travis. (pull request 98)

Issue 104 turned up a problem with one of the tests when using newer
versions of HDF5. This test can be removed.

Fix small typo in code comments. (pull request 105)

Make sure to use python 2, even if 3 can be found since some of the
dependent binaries don't support it. (pull request 108)

Fix typo in CMake Cxx11 variable name mentioned in Issue 115.

##-*****************************************************************************

2016-11-7, Alembic 1.7.0
Hello Alembic users,

Thanks to your feedback we are introducing the new layering functionality to Alembic, as discussed here:

https://groups.google.com/forum/#!topic/alembic-discussion/s0zm8VEBMOk

AbcCoreLayer was developed collaboratively between Blizzard Entertainment and Sony Pictures Imageworks and is a way for you make sparse changes to an Alembic file by writing those changes into any number of other Alembic files, and combining them on read via AbcCoreLayer.

Here are some examples of what you can do via layering:

You can add additional properties to a shape.
Example: Adding UVs to a polymesh that currently lack them

You can override properties.
Example: Override static points on a polymesh with animated points.

You can add new objects.
Example: Add a shape to an existing hierarchy.

You can prune objects.
Example: Remove shapes you don't like, or entire branches of the hierarchy.

You can prune properties.
Example: Removing incorrect normals.

You can replace an object hierarchy with a different one.
Example:  You can replace separate curves groups with one big one.

You can replace property hierarchy.
Example:  Don't like a bunch of properties in user properties?  It can be replaced with a bunch of other properties, without needing to prune individual properties.

AbcCoreLayer provides a SetPrune and SetReplace convenience function in Util.h, for setting up the MetaData appropriately.

Maya:

AbcImport: Support AbcCoreLayer by specifying more than one file to the AbcImport command.

AbcExport:
Support writing only UVs via -uvsonly or -uvo flag.

Utilities:
AbcDiff: Given 2 Alembic files, create a sparse diff between them.

Other changes:

API:

Internally keep track of how many bytes we've written to reduce the number of potentially expensive calls on write.

https://github.com/alembic/alembic/pull/90

Harden some unnecessary templated constructors in Abc and AbcGeom.

Deprecate (but do not remove) constructors that take the kWrapExisting and kTop flag and provide reasonable constructors that don't use these flags in Abc and AbcGeom.

##-*****************************************************************************

2016-7-12, Alembic 1.6.1
Hello Alembic users, thanks to your feedback and reports we have a few bug
fixes and enhancements.

API:

OPoints::setFromPrevious was not setting the previous velocity sample.
(pull request 85)

Fix small bug with AbcCoreOgawa::StreamManager COMPARE_EXCHANGE macro on Windows
(pull request 86)

Maya:

Fix some unused variable warnings in AbcImport, AbcExport.

Utils:

AbcStitcher: Support stitching mixed indexed and non-indexed GeomParams.

##-*****************************************************************************

2016-6-30, Alembic 1.6.0
Thanks to your generous feedback and code contributions we are happy to announce
the 1.6.0 release of Alembic.

We've overhauled our build system, gotten rid of alembic_bootstrap.py in favor
of going native CMake. We now better support Windows and also now require at
least version 2.8.11 of CMake.

For the latest build instructions please see:
https://github.com/alembic/alembic/blob/master/README.txt

Other changes include:

Moved several core utilities out of examples and into bin.

Make HDF5 an optional dependency.

Allow install directory prefix to be explicitly set.
(pull request 46)

Add CMake generated configure file, so that the version of the project only
needs to be set in one place, users know if Alembic was built without HDF5
support, and whether it is using tr1, boost, or neither. (C++11) as a
dependency.

API:
Add ability to create a Windows dll, and add symbol visibility flags for other
compilers. (pull request 14)

Improve Ogawa write speeds on Windows by adding a larger buffer.
(pull request 38)

Make the 3 int values on OSubD optional.
(faceVaryingInterpolateBoundary, faceVaryingPropagateCorners, and
interpolateBoundary issue 34)


Remove unnecessary scoped static initialization of some variables. (issue 27)

Arnold Procedural:
Add Ogawa support. (pull request 20)

Maya:
Support exporting MFnFloatArray. (pull request 45)

Fix bug when Nurbs curves group are only animated via the transforms and speed
up the isAnimated check. (pull request 82)

Many AbcImport/AbcExport changes based on feedback and contributions from
Autodesk, and to bring the plugins more into line with what is in the devkit.
(pull request 51 and 62 through 79)

##-*****************************************************************************

2015-1-15, Alembic 1.5.8
Hello Alembic users, thanks to your feedback and reports we have a few bug
fixes and enhancements.

API:

AbcCoreAbstract:
Fix wstring array hash calculation. (pull request 17)

Build system:
Make the OS X version check more robust to determine if C++11 flag is required.
(pull request 18)

Python:

PyAlembic:
Add asOgawa option for PyOArchive and make Ogawa the default for
CreateArchiveWithInfo. (pull request 16)

##-*****************************************************************************

2015-12-09, Alembic 1.5.7
Hello Alembic users, thanks to your feedback and reports we have a few bug
fixes and enhancements.

Python:

Add missing methods to IPoints.
Add Points schema to cask.
(pull request 12)

Cask:
Add oproperty mapping for additional imath classes.
Add iproperty to oproperty class mapping using pod, extent values.
Remove named oproperty override mapping (replaced by above methods).
Add metadata accessor to property class.
Fix is_deforming method on objects.
(pull request 15)

Maya:

AbcExport:
Add support for writing out all UV sets on an MFnMesh with the
-wuvs/-writeUVSets flag. (pull request 13)

AbcImport:
Support loaidng multiple UV sets on an MFnMesh when present. (pull request 13)

##-*****************************************************************************

2015-10-17, Alembic 1.5.6
Hello Alembic users, thanks to your feedback and reports we have a few bug
fixes and enhancements.

API:

AbcCoreAbstract:
Improve stability of TimeSamplingType equality comparison. (pull request 11)

Maya:

AbcExport:

Recognize "faceVaryingInterpolateBoundary" not "facVaryingInterpolateBoundary"
plug when writing out an MFnMesh as a SubD. (pull request 6)

Don't produce an error for meshes without valid per-face mapping, e.g. whole
object mappings. (pull request 6)

Only create face sets for shading groups applied with with per-face mappings.
(pull request 6)

Make sure a schema that is detected to be static is written out with the
default time sampling. (pull request 7)

AbcImport:

Don't warn about UVs or normals size being mismatched if the mesh has no
points.  (pull request 8)

Connections to custom VectorArray and PointArray properties will no longer fail.
(pull request 8)

Support varying or vertex color properties and unpacking them into facevarying
as Maya requires. (pull request 8)

Only call setUsedAsColor for attributes that are constant scoped.
(pull request 8)


Utilities:

AbcStitcher:
Revamp AbcStitcher to better handle cases where certain shapes or properties
may not exist in some of the files. (pull request 7)

Build system:

Boost_PYTHON_LIBRARY is case sensitive. (pull request 8)



##-*****************************************************************************

2014-07-15, Alembic 1.5.5
Hello Alembic users, thanks to your feedback and reports we have a few bug
fixes and enhancements.

API:

AbcGeom:
Fix bug in OSubD::setHoles where corner indices were being set instead.

AbcCoreAbstract:
Improve lookup times and numerical stability of TimeSampling.

AbcOpenGL:

Camera rotations are now done in X,Y,Z order instead of Z,X,Y

Python API:

PyAlembic:
Address Issue 347, expose the CoreType in python.

PyAbcOpenGL:
Wrap ALEMBIC_LIB_USES_BOOST around get_pointer.

Maya:

AbcExport:
If a shading group has an attribute named AbcFaceSetName, use that attribute
instead of the shading groups name for the face set name.

Fix for Issue 339, some dag nodes can't be pushed onto MDagPath, so make sure
the push was successful to avoid infinite recursion.

Fix for Issue 342, for improved performance skip over shadingEngines and
subgraphs in util::isAnimated.


AbcImport:
Set AbcFacesetName attribute on newly created shadingGroups.

Fix bug with open form check on curves.

Fix bug with restoring knots from a curve group with more than one curve.

Tools:

AbcView:
Fix for Issue 344, show array property values of length 1.

Improve performance for some graphics cards by adjusting some drawing options.
(also done in SimpleAbcViewer)

abcls
Add -v option to automatically display the first sample of all properties.
Print an error message when seg fault is detected.

cask:
Fix for Issue 345, handle V3d and double array on write.
Default to Ogawa on write.

Fix for Issue 346, TimeSampling is now preserved for properties that are
copies on write.

##-*****************************************************************************

2014-03-28, Alembic 1.5.4
Hello Alembic users, thanks to your feedback and reports we have a few bug
fixes and enhancements.

API:

AbcGeom:
Fix for Issue 333,  optional property samples not being filled in correctly
after being defined previously but not set on the current sample.

AbcOpenGL:

Fix for Issue 324, adjust dolly and clipping plane values when they get
a bit extreme.

Python:
Updates for sphix docs

AbcView:
Fix static normals on animated archives.
Fix remove item bug.
Fix import session fle bug.
Add Review mode.
Support custom scripts.

Maya:

AbcExport:
Write out NURBS curves as actual NURBS curves.

AbcImport:

Support reading NURBS curves.
Use Alembic::Util::shared_ptr instead of std::tr1::shared_ptr in one spot.

Util:

AbcEcho:

Fix bounds calculation on AbcBoundsEcho.
Add an optional seconds argument for time sampling support.

Build:

Use C++11 for OSX Mavericks.
Define ALEMBIC_LIB_USES_BOOST to accomodate python bindings.
Use LIBPYTHON_VERSION to determine which python to use.

##-*****************************************************************************

2013-12-17, Alembic 1.5.3
Hello Alembic users, thanks to your feedback and reports we have a few bug
fixes and enhancements.

API, Ogawa:

Don't open extra filestreams until they are needed.

Maya, AbcImport:
Fix for issue 251, if connections to the immediate children of the archive fail
warn about it.

Relax naming constraints on connection so that if the namespace is different
between the Maya scene and the Alembic archive, they can still connect.

Specifying a Maya node to -connect which doesn't match any of the children of
the immediate root of the archive, try and connect below that specified Maya
node.

Python:

cask:
Fix for issue 318, make sure the archive gets released properly.

abcview:
Fix bug where animated normals weren't being updated for display.

##-*****************************************************************************

2013-12-6, Alembic 1.5.2
Hello Alembic users, thanks to your feedback and contributions we have another
collection of bug fixes and enhancements to the API.

API:

Add Nurbs Curves support to I/OCurves, also addresses Issue 249.
Most reference implementations have not yet been updated to support it.

Add SetSourceName, GetSourceName, SetIsUV, isUV utility functions and
setUVSourceName member function on OPolyMeshSchema and OSubDSchema.

Don't assert in TimeSampling::getNearIndex if the floor index and the ceil index
are the same.

Address several clang compile warnings.  Part of Issue 322.

AbcCoreHDF5 and AbcCoreOgawa:
Fix reported thread-safety issues.

Python bindings:

Fix for issue 326.
"error: control reaches end of non-void function" in PyIArchive

Add Nurbs Curves support to I/OCurves.
Note: The expected number of knots per curve is the number of vertices in the
curve plus the order of the curve.

Add SetSourceName, GetSourceName, SetIsUV, isUV utility functions and
setUVSourceName member function on OPolyMeshSchema and OSubDSchema.

AbcOpenGL:
Fix for issue 324, clamp values instead of asserting.

Misc Tools:

AbcStitcher:
Support stitching Nurbs curves.
Fix bug where the output file would only be HDF5.
Fix bug where invalid metadata and name were used for leftover objects.
Fix bug where top object was gotten before checking for archive validity.
Add additional check and error message if the number of children nodes aren't
the same between the IObjects from different archives.

AbcTree:
Rename variable to fix shadow warning on some compilers.  Issue 320.
Windows compatibility fix, S_ISDIR doesn't exist.

AbcLs:
Windows compatibility fix, S_ISDIR doesn't exist.
Fix the way certain scalar properties print.

##-*****************************************************************************

2013-9-18, Alembic 1.5.1
Hello Alembic users, thanks to your feedback we have another collection of
small but useful bug fixes and enhancements to the API, some of the example
tools, and the Maya plugins.

API:

IXform/OXform:
Make default identity xforms use even less disk space.
Fix for Issue 313: IXformSchema::getInheritsXforms() crash with no samples

Python bindings:
Fix for Issue 308: ILightSchema.getCameraSchema() segfaults when no cameras
are available

Maya:

AbcImport:
Fix for Issue 311: properly set SubD creases, corners, and holes when the
geometry is animated

Fix for Issue 312: AbcImport doesn't accept long names when filtering

AbcExport:
Ogawa is now written out by default. (when the -dataformat flag isn't specified)

Multiple frame ranges can be specified for more control over the samples
exported.

-preRoll flag was added for specified frame ranges that you want evaluated but
not exported.

Misc Tools:

AbcLs - fix bugs, added new flag -s to view the size of a scalar or array
property, -t for printing time info of the archive and the time a sample
index of a property corresponds to.  -f prints out the frame assuming 24fps.

AbcView - tweaked docs, lots of bug fixes, better camera support

prman Procedural - Fix for Issue 314: subdiv tags could become corrupted.

##-*****************************************************************************

2013-7-22, Alembic 1.5.0
Hello Alembic users, we are pleased to announce the official release of a new
data back end for Alembic, codenamed Ogawa with improved write, read, and
especially multi-threaded read performance.

Here are some improvements we are seeing with this version:

1) File sizes are on average 5-15% smaller. Scenes with many small objects
should see even greater reductions.

2) Single-threaded reads average around 4x faster

3) Multi-threaded reads can improve by 25x (relative to the same operations in
the existing HDF5 back-end) on 8 core systems.

We are maintaining backwards compatibility, and you will be able to continue to
read and write Alembic files backed by HDF5.

Other library features added:

Support for explicit hierarchical deduplication. (OObject::addChildInstance)

Hierarchical hash keys added to objects, making it easier to compare sub-graphs
of various archives. (IObject::getPropertiesHash, IObject::getChildrenHash)

Add AbcCoreFactory::IFactory class which is a convenience class for determining
whether an archive is backed by HDF5 or Ogawa and returning a properly
instantiated IArchive.  All of the readers in the repository have been updated
to use this.

Python bindings have been extended to support the new features above.

New utility:

abcls this utility is meant to behave like ls or h5ls and offers an
inexpensive way to explore your object and property hierarchies.

Bug fixes:

ICamera:
Getting the film back xform channels needs to be done by index.
Animated film back data wasn't being reflected in isConstant.
Offset data should be applied after the filmback matrix.

AbcExport: preScale, and postScale film back xform should be 1.0/scale.

##-*****************************************************************************

2013-4-11, Alembic 1.1.5
Hello Alembic users, thanks to your feedback we have another collection of
small but useful bug fixes and performance enhancements for the Maya plugins.

AbcExport:

Improve the performance of util::isAnimated.

If MFnIkJoint's Scale Compensate is off, [IS] is ignored otherwise multiply it
after [T].  [IS] is actually the inverse of the inverseScale plug.

Fixed const related error caught by Microsoft Visual Studio 9.0 compiler.

AbcImport:

Use createPoint and createColor for MFnNumericAttribute when appropriate.

##-*****************************************************************************

2013-03-25, Alembic 1.1.4
Hello Alembic users, thanks to your feedback we have another collection of
small but useful and important bug fixes.

Fix several multi-platform issues to making compiling in Windows and OSX easier.

PyAlembic:

Fix typo XformSample::getZRotation should be XformSample::getScale.

AbcImport:

Directly set the string plug, as the default value is not saved to the Maya
file and thus is not restored.

AbcExport/AbcImport:

Fix bug where the conversion from shutter open, shutter close to shutter angle
was being improperly scaled.

##-*****************************************************************************

2013-02-11, Alembic 1.1.3
Hello Alembic users, thanks to your feedback we have another collection of
useful features and bug fixes.

Alembic library:

Add missing setTimeSampling member function to OCurves and ONuPatch. (Issue 295)

Record the max number of samples written for various TimeSampling at the
archive level, and provide a utility function for getting the start and end time
of the archive using this data.  (Issue 301)

Propogate the Error handling policy better.

Add Box2(s,i,f,d) array properties to match scalar properties.

INuPatch getTopologyVariance wasn't correctly taking into account animated
weights.

IsAncestorVisible utility function was returning the wrong value.

TimeSamplingType now allows for some floating point imprecision during
comparison. (Issue 301)

Add isStandardName and makeStandardName convenience functions.

    - These functions offer plugin writers an easy way to get multi-application
      name compliance.  They help you convert any special characters your
      application supports into a set universally accepted characters.

Add AbcOpenGL library which is based on the draw code from SimpleAbcViewer.

Python:

Add PyAbcOpenGL bindings.

Fix segfault with invalid getProperty index/name

Add getProperty to OCompoundProperty

Add getKey to IArrayProperty

    - This is the preferred way to get the alembic hash of a property.
      Previously you needed to build the a hash by marshalling
      and serializing the data in python which is slooow.

Add getMaxNumSamplesForTimeSamplingIndex to IArchive.

Add high level Python API named "cask" built on top of the Alembic Python
bindings.

    - This was developed to simplify scripting of alembic files
      in Python.

    - It is designed to be easy to use and "Pythonic". For example it
      gives you a dictionary style interface to objects and
      properties.

    - It is an abstraction on top of alembic which allows you to create mutable
      objects. This means scripters are not forced to use the separated,
      immutable input and output core alembic objects.

    - We will host documentation on docs.alembic.io shortly but for now please
      convert the cask.rst file in python/examples/cask/doc to read the docs
      and see examples.

Add abcview which uses PyQt and PyAbcOpenGL

    - This tool is perfect for debugging alembic caches. It offers Katana-
      style, lazy-UI hierarchy traversal and a script editor to do more
      in-depth object and property queries using the Python bindings.
      SimpleAbcView is embedded into the application for easy reference.

Bootstrap and CMake:

Fix boost configuration if you are not building pyalembic. (Issue 296)

Eliminate many warnings when compiling with Visual Studio 10. (Issue 294)

Improve many of our CMakeLists.txt so that you can use Cmake directly instead
of having to go through the bootstrap.

Better Windows compliance. (Look for further improvements over the next releases).

Maya:

AbcExport bounding box calculation for the entire archive is much more efficient
and is especially noticeable when calculating bounds on deep hierarchies.

Add identifyFile and haveNamespaceSupport to AlembicImportFileTranslator.

Fix bug where the AlembicImportFileTranslator could not be unloaded properly.

Arnold Procedural:

Fix bug with multiple samples potentially being added for uvlist.

Initialize makeInstance on creation.

Add instanced nodes to the list of createdNodes.

Utilities:

Add abctree which walks the entire hierarchy and prints out the names
of objects.

##-*****************************************************************************

2012-10-17, Alembic 1.1.2
Hello Alembic users, thanks to your feedback we have another collection of
small but useful features and bug fixes.

New features:

Maya AbcImport:

Added inclusive and exclusive filtering support to allow selective importing
of cache objects via regex matches.

Added file translator support. Alembic caches can now be opened directly and
imported as Maya references.

Facesets now get imported as Maya facesets instead of an integer array
attribute.

Maya AbcExport:

Write out curves with a basis of b-spline and repeat first and last
points twice (if they aren't repeated) if we have a cubic open curve.

Support exporting Maya facesets with the -wfs/-writefacets flag.

Add -ef/-eulerFilter flag which euler filters samples to rotate, rotate axis,
and joint orient.

Update -sn/-stripNamespaces flag with an optional integer to only strip
that number of namespaces.

Remove boost usage.

Core library:

Add static emptySample() convenience function.

Improve const correctness on most of the Abc and AbcGeom getter functions.

Child bounds are no longer written and read via the schema's sample class,
instead the child bounds property is directly exposed on the schema.

Normals and UVs IGeomParams are no longer returned by reference.

On Xforms, only write the .animChans data once if necessary.

Bug fixes:

Maya AbcImport:

Clean up temporary trim curves when the trim operation fails for
MFnNurbsSurface.

##-*****************************************************************************

2012-9-20, Alembic 1.1.1
Hello Alembic users, thanks to your feedback we have another collection of
small but useful and important bug fixes.

Bug fixes:

Issue 291
Fix for some compile issues/warnings on Windows.

Issue 292
Hash keys are being computed incorrectly on Windows.

Some small CMake updates.

Fixed typo in OSubD::setHoles

##-*****************************************************************************

2012-7-26, Alembic 1.1.0

Hello Alembic users.  We are excited to announce another release of Alembic
which contains many new features, bug fixes and performance improvements.

What's new:

- AbcCollections. Alembic now supports the concept of a collection.  Sometimes
people refer to collections as "groups" or "object sets" (as in Maya).

- AbcMaterial.  Alembic now supports the concept of a material. This is done by
defining a schema for a material definition which can act as a standalone object
or as supplemental data attached to another object. AbcMaterial also defines
conventions and utilities for binding and resolving marterial assignments
and overrides. We have not gone as far as defining what a material schema should
actually contain (as we did with cameras); instead we allow you to define your
own material "target" to allow all the many variations in material standards
that exist today. However we have reserved the name "abc" for a target
we will define at a later time; the hope is that this material target would
become the standard for material interchange.

- AbcLight. Alembic now supports the concept of a light. Light objects are
distinct objects that contain both a camera and a material schema.  The material
on the light controls the shader parameters associated with the light and the
camera can contain all relevant camera-like light information.

- Python bindings.  At long last the Alembic team has finally completed the
python bindings to allow scripters to access the full power of the alembic
c++ api. All the new features listed above as well as the layers Abc though
AbcGeom are bound. The base bindings of typed data (including typed arrays)
are pyimath types so if your program can natively create imath data types
there is no performance penalty to convert to and from alembic types.

- Performance optimization. When we profiled Alembic we found that, for some
caches, a great deal of time was being spent in HDF5 functions that access
groups and attributes by name.  We now let you optionally write a side car
datastructure within the HDF5 file that maps the HDF5 hierarchy to HDF5 object
references which results in lookups that are  much faster. You pay the price
of a slight disk size increase and memory footprint.

- Maya plugin updates. The ".userProperties" compound property that is available
on most Alembic objects is now supported for both read and write with full
support for animated values. Additional parameters have also been added to the
AlembicNode to allow cache retiming along with support for loop, reverse and
bounce.

- Boost removal from the core. We are no longer dependent on boost to give us
an implementation of a shared pointer (for example) so we were able to remove
the dependency on boost while building the core library.

Bug Fixes:

Issue 171:
OScalar and OArray Properties had a scoping issue when parented to the immediate
child compound property of an OObject.

Issue 245:
I<type>GeomParam would match to properties that aren't geom params.
IArrayProperty is always considered a geom param with constant scope.

Issue 253-255
Several bugs involved with the -rm flag on AbcImport have been fixed.

Issue 263
AbcExport UV write fix, loop over all faces, not just the faces which have UVs.

Issue 275
AddGeomToParamListBuilderAsFloat was calculating wrong boundary for the
IV2fArrayProperty.

Issue 280
Accomodate Unicode file names in AbcImport and AbcExport.

Issue 285
AbcGeom/Basis.h was not including Alembic/Util/Foundation.h

##-*****************************************************************************

2012-2-14, Alembic 1.0.5

Bug fix release.

Fix for issue 272.

Core:

String dimensions weren't being written correctly for string arrays when copying
a previous sample.

Correctness updates to "matches(..)" (data matching functions).

Houdini plugin:
Reverting frame - 1 change.
Including a clear cache function.

##-*****************************************************************************

2012-1-12, Alembic 1.0.4

Hello, Alembic users, thanks to your feedback we have another collection of
API additions and small but useful bug fixes.

Some highlights:

API:

 - Now supports raw reads, and reading as a different precision, for array properties
 via a new method getAs (). Currently strings, wstrings, and float16_t
 can not be read as any other type.

 - Added an optional velocity property to polymeshes, subds, nurbs, and curves.
 Velocity is considered to be in units per second.

 - Added a temporary work around for an HDF5 bug where parts of the file could become
 corrupt. This workaround always stores the HDF5 links in dense storage.  This can lead to
 larger file sizes when you have a lot of IObjects.

 - Improved the performance on partial hierarchy traversal by deferring opening of an
 object's HDF5 group until truly needed.

Renderman Procedural:

 - Added support for V3dGeomParam, P3dGeomParam, and BoolGeomParam

Houdini SOP:

 - Dramatically increased the performance under Houdini 12 and pleasantly increased
 performance under 11.1.

Maya AbcImport:

 - Don't interpolate when the time values closely match the ceiling value.

 - Don't create a new color set every time an animated color set is evaluated.

 - Interpolating non indexed color values would sometimes cause a crash.

We welcome your comments on the discussion list.

http://groups.google.com/group/alembic-discussion

##-*****************************************************************************

2011-11-11, Alembic 1.0.3

Hello, Alembic users, thanks to your feedback we have another collection of
small but useful bug fixes to our plugins.

Some highlights:

Renderman Procedural:

 - Addition of Windows export information for ConvertParameters/Subdivide/Free

 - Fixed an uninitialized variable for -flipv

 - Fixed a string-related memory bug for declarations in ParamListBuilder
(issue 241)

 - Addition of support for reading, caching and sharing argument strings from
files.

 - Addition of support for restoring named resource blocks at specified paths
or names for objects and facesets

 - Fixed support for getInheritsXforms in IXforms (issue 247)

 - Fixed CMake where it failed to find libprman.lib because of a typo
(issue 229)

Maya AbcImport:

 - Fixed compilation with Maya 2011 by adding an ifdef for the
setDisplayColors(true) call.  (issue 244)

 - Fixed some issues with the -connect option.  Transforms weren't being
properly cleared when connection.

Maya AbcExport:

 - Change for FBIK joints, there isn't always a connection to translate or
scale (like rotate for IK joints).  We now treat them like they are animated.

 - Return an error if the file can't be written to.

 - The full -renderableOnly flag was not properly being detected (issue 252)

We welcome your comments on the discussion list.

http://groups.google.com/group/alembic-discussion

##-*****************************************************************************

2011-10-12, Alembic 1.0.2

Hello, Alembic users, thanks to your feedback we have another collection of
small but useful bug fixes and a couple of new flags for some of our plugins.

Some highlights:

- In Maya don't flip V when reading and writing UVs. (AbcExport and AbcImport)

- Add a flag (-flipv) to the prman Procedural to flip V when necessary.

- Add a flag (-wcs / -writeColorSets) to AbcExport to write out color sets and
restore them on AbcImport.

- In AbcExport the -renderableOnly flag was doing the opposite of what it was
supposed to do.

- Fix bug in SimpleAbcViewer where XformSchema::getInheritsXforms() was not
being respected.

- Fix bug in AbcStitcher to prevent a segfault.

We welcome your comments on the discussion list.

http://groups.google.com/group/alembic-discussion

##-*****************************************************************************
2011-09-15, Alembic 1.0.1

Hello, Alembic users, we've gotten great feedback from the community
and with their help we've created this collection of small but useful
bug fixes.

Some highlights:

 - A collection of useful bug fixes in the Maya AbcExport and AbcImport
   plugins

 - The renderman procedural has some small bug fixes, e.g. fixes related
   to arbitrary geometric parameters

As always, any files generated by either Alembic 1.0.0 or
Alembic 1.0.1 will interoperate. If you are working in Maya
we encourage you to look at this update.

The complete code changes for this release can be examined here:

http://codereview.appspot.com/4978066/

We welcome your comments on the discussion list.

http://groups.google.com/group/alembic-discussion


##-*****************************************************************************
2011-08-09, Alembic 1.0

Hello, Alembic users, welcome to our first gold release of Alembic.

The complete code changes for this release can be examined here:
http://codereview.appspot.com/4819067/

Some highlights:

 - Addition of the Arnold procedural.

 - Removal of some things that weren't Alembic related (GLUtil)

 - Addition of a python unit test suite for AbcExport and AbcImport.

 - Lots of Houdini SOP improvements.

 - Cleanup of many compiler warnings.

This initial 1.0 version can now be used for critical, deadline-driven
production work.

Also as usual, feedback and questions are welcome!  The main discussion list
is low-traffic, but anyone can sign up and participate:

http://groups.google.com/group/alembic-discussion

##-*****************************************************************************
2011-06-28, Alembic 1.0rc1

Hello, Alembic users, welcome to the latest beta version of Alembic.  As we
close in on a 1.0 release, we hope the API and file format are now stable
and fully forwards-compatible.  We consider these to be at a first
"Release Candidate" stage. (note that this doesn't yet apply to the
application-specific reference implementations). As with all pre-release
software, we can't guarantee that changes won't occur between now and a full
1.0 release.

This release is mostly a bugfix and cleanup release.  We've improved the build
support for Windows and OS X, as well as conformed the definitions of the Curves
and NuPatch types more closely to the RI spec.  Those changes, though, do mean
that Curves and NuPatch geometry written out with previous releases will not be
recognized with this release.

The complete code changes for this release can be examined here:

http://codereview.appspot.com/4662068

Some highlights:

 - The flags and arguments for the AbcExport Maya plugin have been updated
   based on feedback from the community, and to be more Maya-idiomatic.
   You can see all the arguments supported by entering "AbcExport -h"
   in the script editor.

 - The Makefile setup for the AlembicIn Houdini SOP is greatly simplified,
   though still not fully integrated with Alembic's CMake setup.

 - The PRMan procedural now supports the Points, NuPatch, Curves, and FaceSet
   types from AbcGeom.

One other important thing to note: previous releases of Alembic did not
require any of the compiled Boost libraries, but going forward, Alembic
requires libboost_thread.

Although this is our initial 1.0 release candidate, it should still be
considered pre-release software, and should not be used for critical, deadline-
driven production work.

Also as usual, feedback and questions are welcome!  The main discussion list
is low-traffic, but anyone can sign up and participate:

http://groups.google.com/group/alembic-discussion

As always, discussion is welcome on the discussion list.

##-*****************************************************************************
2011-05-18, Alembic 0.9.3:

The biggest news in this release is what we hope is the complete set of
geometric types for ALembic 1.0, which includes curves (fashioned after
RiCurves), nurbs surfaces, facesets in polygons and subds, and a camera
definition. See http://code.google.com/p/alembic/wiki/Alembic_Geometric_Types
for a complete list.

The complete code changes for this release can be examined here:

http://codereview.appspot.com/4517085

Some highlights:

 - There is now a single class for expression transforms. Preivously
   we had both SimpleXform and Xform objects for expressing transformation.
   The new unified Xform class can be used more simply than the old
   Xform class, while retaining the expressivity of the original.

 - We have experimental support for building Alembic on Windows. Details
   for how to perform the build can found in build/Windows/README.txt and
   build/Windows/WindowsBuildSteps.html

 - We've changed the API in a couple places, most notably, in the way
   instances of the class class Alembic::AbcCoreAbstract::TimeSampling are
   stored and referenced.

 - There is a reference Houdini SOP that can read an entire Alembic archive
   or a subtree of an archive with the option to bake in transformations. As
   such, it could also serve as the "leaf" node for an import process which
   rebuilt the full transformation hierarchy within Houdini. The intention is
   to pair this with a CHOP (not slated for inclusion this round) which extracts
   transformation channels from the archive.  However, it is not yet integrated
   into the Alembic build infrastructure, so compiling it may take some work.

As this is still a 0.9 release, it is still to be considered Beta, and
should not be used for critical, deadline-driven production work.

Also as usual, feedback and questions are welcome!  The main discussion list
is low-traffic, but anyone can sign up and participate:

http://groups.google.com/group/alembic-discussion

As always, discussion is welcome on the discussion list.

##-*****************************************************************************

2011-02-17, Alembic 0.9.2:

This is somewhere between a major and minor update.  Numerous bugs
have been fixed, some new functionality has been introduced, and
reference Maya plugins for import and export have been added.

The code changes can be examined here:

http://codereview.appspot.com/4160045/

Some highlights in functionality:

 - Maya export and import plugins are in the top-level "maya" directory.

 - In the top-level "python" directory is the beginning of Python bindings
   using Boost.Python.  This effort is currently incomplete, but with
   these bindings, the structure of an Alembic Archive can be examined.

 - UVs on PolyMeshes and SubD meshes, as well as Normals on PolyMeshes,
   are included in their definition, and can be written and read as
   indexed arrays or expanded, non-indexed arrays, with automatic
   interconversion between the two representations.

As this is still a 0.9 release, it is still to be considered Beta, and
should not be used for critical, deadline-driven production work.

Also as usual, feedback and questions are welcome!  The main discussion list
is low-traffic, but anyone can sign up and participate:

http://groups.google.com/group/alembic-discussion

As always, discussion is welcome on the discussion list:

##-*****************************************************************************

2010-12-13, Alembic 0.9.1:

Just a minor update to enable Alembic on 32-bit systems, along with
getting the code in examples/bin/AbcEcho reasonably working.

2010-12-08, Alembic 0.9.1:

The main things in this release are the addition of a Renderman procedural
plugin, and a bunch of bug fixes.  The example Maya exporter
(AlembicSimpleAbcExport) can be used to create an Alembic file from a Maya
scene, and that Alembic file can be read by the Renderman plugin to create
images, which means that an end-to-end workflow can be achieved.  A complete
overview of the changes to the code is here:

http://codereview.appspot.com/3427045

A summary of the bugs fixed in this change:

http://code.google.com/p/alembic/issues/detail?id=71

An internal implementation detail that fixed an issue where files created by
the AlembicSimpleAbcExport Maya plugin were invalid.

http://code.google.com/p/alembic/issues/detail?id=118

Another internal implementation bugfix that ensured that certain properties of
a subdivision surface were properly animatable.

http://code.google.com/p/alembic/issues/detail?id=17

Method to return a Property's parent Object simply did not work.

http://code.google.com/p/alembic/issues/detail?id=121

Methods to determine high-level type now more flexible and correct.

http://code.google.com/p/alembic/issues/detail?id=7

Build system improvement; now behaves better when trying to find the Boost
headers and libraries.

http://code.google.com/p/alembic/issues/detail?id=13

A consequence of the bug that was fixed in issue 71.

http://code.google.com/p/alembic/issues/detail?id=123

Alembic was not reading all the required data from an ISimpleXform.


In progress, we have:

http://code.google.com/p/alembic/issues/detail?id=102

This is an arbitrary transform "stack" type, roughly equivalent to Renderman's
transformation model.  It has per-operation hints that allow it to be
recognized as a transform and mapped directly to another application's
transformation model.  It can also be read and written as a regular 4x4
matrix.

##-*****************************************************************************
