/**

@page changes Release Notes


@par
<B>Version 0.104.0</B> - <I>February 15 2013</I>
- Added a @vdblink::tools::levelSetRebuild() tool@endlink and a SOP
  to rebuild a level set from any scalar volume.
- @c .vdb files are now saved using a mask-based compression scheme
  that is an order of magnitude faster than Zip and produces comparable
  file sizes for level set and fog volume grids.  (Zip compression
  is still enabled by default for other classes of grids).
- The @vdblink::tools::Filter Filter@endlink and
  @vdblink::tools::LevelSetFilter LevelSetFilter@endlink tools now
  include a Gaussian filter, and mean (box) filtering is now 10-50x faster.
- The isosurface @vdblink::tools::VolumeToMesh meshing tool@endlink
  is now more robust (to level sets with one voxel wide narrow bands,
  for example).
- Mesh to volume conversion is on average 1.5x faster and up to 5.5x
  faster for high-resolution meshes where the polygon/voxel size ratio
  is small.
- Added @vdblink::createLevelSet() createLevelSet@endlink and
  @vdblink::createLevelSetSphere() createLevelSetSphere@endlink
  factory functions for level set grids.
- @vdblink::tree::ValueAccessor tree::ValueAccessor@endlink is now faster
  for trees of height 2, 3 and 4 (the latter is the default), and it now
  allows one to specify, via a template argument, the number of node levels
  to be cached, which can also improve performance in special cases.
- Added a toggle to @vdblink::tools::foreach() tools::foreach@endlink
  to specify whether or not the functor should be shared across threads.
- Added @vdblink::Mat4SMetadata Mat4s@endlink and
  @vdblink::Mat4DMetadata Mat4d@endlink metadata types.
- Added explicit pre- and postmultiplication methods to the @c Transform,
  @c Map and @c Mat4 classes and deprecated the old accumulation methods. 
- Modified @vdblink::math::NonlinearFrustumMap NonlinearFrustumMap@endlink
  to be more compatible with Houdini&rsquo;s frustum transform.
- Fixed a @vdblink::tools::GridTransformer GridTransformer@endlink bug
  that caused it to translate the output grid incorrectly in some cases.
- Fixed a bug in the tree-level
  @vdblink::tree::LeafIteratorBase LeafIterator@endlink that resulted in
  intermittent crashes in
  @vdblink::tools::dilateVoxels() tools::dilateVoxels@endlink.
- The @c Hermite data type and Hermite grids are no longer supported.
- Added tools/GridOperators.h, which includes new, cleaner implementations
  of the @vdblink::tools::curl() curl@endlink,
  @vdblink::tools::divergence() divergence@endlink,
  @vdblink::tools::gradient() gradient@endlink,
  @vdblink::tools::laplacian() Laplacian@endlink, 
  @vdblink::tools::magnitude() magnitude@endlink,
  @vdblink::tools::meanCurvature() mean curvature@endlink and
  @vdblink::tools::normalize() normalize@endlink tools.
- Interrupt support has been improved in several tools, including
  @vdblink::tools::ParticlesToLevelSet tools::ParticlesToLevelSet@endlink.
- Simplified the API of the @vdblink::math::BaseStencil Stencil@endlink class
  and added an @vdblink::math::BaseStencil::intersects() intersects@endlink
  method to test for intersection with a specified isovalue.
- Renamed @c voxelDimensions to @c voxelSize in transform classes
  and elsewhere.
- Deprecated @c houdini_utils::ParmFactory::setChoiceList in favor of
  @c houdini_utils::ParmFactory::setChoiceListItems, which requires
  a list of <I>token, label</I> string pairs.
- Made various changes for Visual C++ compatibility.
  <I>[Contributed by SESI]</I>
- Fixed a bug in @c houdini_utils::getNodeChain() that caused the
  Offset Level Set, Smooth Level Set and Renormalize Level Set SOPs
  to ignore frame changes.
  <I>[Contributed by SESI]</I>
- The From Particles SOP now provides the option to write into
  an existing grid.
- Added a SOP to edit grid metadata.
- The Fracture SOP now supports multiple cutter objects.
- Added a To Polygons SOP that complements the Fracture SOP and allows
  for elimination of seam lines, generation of correct vertex normals
  and grouping of polygons when surfacing fracture fragments, using
  the original level set or mesh as a reference.


@par
<B>Version 0.103.1</B> - <I>January 15 2013</I>
- @vdblink::tree::ValueAccessor tree::ValueAccessor@endlink read operations
  are now faster for four-level trees.
  (Preliminary benchmark tests suggest a 30-40% improvement.)
- For vector-valued grids, @vdblink::tools::compMin() tools::compMin@endlink
  and @vdblink::tools::compMax() tools::compMax@endlink now compare
  vector magnitudes instead of individual components.
- Migrated grid sampling code to a new file, Interpolation.h,
  and deprecated old files and classes.
- Added a level-set @vdblink::tools::LevelSetFracture fracture tool@endlink
  and a Fracture SOP.
- Added @vdblink::tools::sdfInteriorMask() tools::sdfInteriorMask@endlink,
  which creates a mask of the interior region of a level set grid.
- Fixed a bug in the mesh to volume converter that produced unexpected
  nonzero values for voxels at the intersection of two polygons,
  and another bug that produced narrow-band widths that didn't respect
  the background value when the half-band width was less than three voxels.
- @c houdini_utils::ParmFactory can now correctly generate ramp multi-parms.
- Made various changes for Visual C++ compatibility.
  <I>[Contributed by SESI]</I>
- The Convert SOP can now convert between signed distance fields and
  fog volumes and from volumes to meshes.
  <I>[Contributed by SESI]</I>
- For level sets, the From Mesh and From Particles SOPs now match
  the reference grid's narrow-band width.
- The Scatter SOP can now optionally scatter points in the interior
  of a level set.


@par
<B>Version 0.103.0</B> - <I>December 21 2012</I>
- The mesh to volume converter is now 60% faster at generating
  level sets with wide bands, and the From Mesh SOP is now interruptible.
- Fixed a threading bug in the recently-added 
  @vdblink::tools::compReplace() compReplace@endlink tool
  that caused it to produce incorrect output.
- Added a @vdblink::tree::Tree::probeConstLeaf() probeConstLeaf@endlink
  method to the @vdblink::tree::Tree::probeConstLeaf() Tree@endlink,
  @vdblink::tree::ValueAccessor::probeConstLeaf() ValueAccessor@endlink
  and @vdblink::tree::RootNode::probeConstLeaf() node@endlink classes.
- The Houdini VDB primitive doesn't create a @c name attribute
  unnecessarily (i.e., if its grid's name is empty), but it now
  correctly allows the name to be changed to the empty string.
- Fixed a crash in the Vector Merge SOP when fewer than three grids
  were merged.
- The From Particles SOP now features a "maximum half-width" parameter
  to help avoid runaway computations.


@par
<B>Version 0.102.0</B> - <I>December 13 2012</I>
- Added @vdblink::tools::compReplace() tools::compReplace@endlink,
  which copies the active values of one grid into another, and added
  a "Replace A With Active B" mode to the Combine SOP.
- @vdblink::Grid::signedFloodFill() Grid::signedFloodFill@endlink
  no longer enters an infinite loop when filling an empty grid.
- Fixed a bug in the particle to level set converter that sometimes
  produced level sets with holes, and fixed a bug in the SOP that
  could result in random output.
- Fixed an issue in the frustum preview feature of the Create SOP
  whereby rendering very large frustums could cause high CPU usage.
- Added streamline support to the constrained advection scheme
  in the Advect Points SOP.
- Added an Advect Level Set SOP.


@par
<B>Version 0.101.1</B> - <I>December 11 2012</I> (DWA internal release)
- Partially reverted the Houdini VDB primitive's grid accessor methods
  to their pre-0.98.0 behavior.  A primitive's grid can once again
  be accessed by shared pointer, but now also by reference.
  Accessor methods for grid metadata have also been added, and the
  primitive now ensures that metadata and transforms are never shared.
- Fixed an intermittent crash in the From Particles SOP.


@par
<B>Version 0.101.0</B> - <I>December 6 2012</I> (DWA internal release)
- Partially reverted the @vdblink::Grid Grid@endlink's
  @vdblink::Grid::tree() tree@endlink and
  @vdblink::Grid::transform() transform@endlink accessor methods
  to their pre-0.98.0 behavior, eliminating copy-on-write but
  preserving their return-by-reference semantics.  These methods
  are now supplemented with a suite of
  @vdblink::Grid::treePtr() shared@endlink
  @vdblink::Grid::baseTreePtr() pointer@endlink
  @vdblink::Grid::transformPtr() accessors@endlink.
- Restructured the @vdblink::tools::MeshToVolume
  mesh to volume converter@endlink for a 40% speedup
  and to be more robust to non-manifold geometry, to better preserve
  sharp features, to support arbitrary tree configurations and
  to respect narrow-band limits.
- Added a @c getNodeBoundingBox method to
  @vdblink::tree::RootNode::getNodeBoundingBox() RootNode@endlink,
  @vdblink::tree::InternalNode::getNodeBoundingBox() InternalNode@endlink
  and @vdblink::tree::LeafNode::getNodeBoundingBox() LeafNode@endlink
  that returns the index space spanned by a node.
- Made various changes for Visual C++ compatibility.
  <I>[Contributed by SESI]</I>
- Renamed the Reshape Level Set SOP to Offset Level Set.
- Fixed a crash in the Convert SOP and added support for conversion
  of empty grids.


@par
<B>Version 0.100.0</B> - <I>November 30 2012</I> (DWA internal release)
- Greatly improved the performance of the level set to fog volume
  @vdblink::tools::sdfToFogVolume() converter@endlink.
- Improved the performance of the
  @vdblink::tools::Filter::median() median filter@endlink
  and of level set @vdblink::tools::csgUnion() CSG@endlink operations.
- Reintroduced
  @vdblink::tree::Tree::pruneLevelSet() Tree::pruneLevelSet@endlink,
  a specialized @vdblink::tree::Tree::pruneInactive() pruneInactive@endlink
  for level-set grids.
- Added utilities to the @c houdini_utils library to facilitate the
  collection of a chain of adjacent nodes of a particular type
  so that they can be cooked in a single step.  (For example,
  adjacent @c xform SOPs could be collapsed by composing their
  transformation matrices into a single matrix.)
- Added pruning and flood-filling options to the Convert SOP.
- Reimplemented the Filter SOP, omitting level-set-specific filters
  and adding node chaining (to reduce memory usage when applying
  several filters in sequence).
- Added a toggle to the Read SOP to read grid metadata and
  transforms only.
- Changed the attribute transfer scheme on the From Mesh and
  From Particles SOPs to allow for custom grid names and
  vector type metadata.


@par
<B>Version 0.99.0</B> - <I>November 21 2012</I>
- Added @vdblink::Grid Grid@endlink methods that return non-<TT>const</TT>
  tree and transform references without triggering deep copies,
  as well as @c const methods that return @c const shared pointers.
- Added @c Grid methods to @vdblink::Grid::addStatsMetadata populate@endlink
  a grid's metadata with statistics like the active voxel count, and to
  @vdblink::Grid::getStatsMetadata retrieve@endlink that metadata.
  By default, statistics are now computed and added to grids
  whenever they are written to <TT>.vdb</TT> files.
- Added @vdblink::io::File::readGridMetadata io::File::readGridMetadata@endlink
  and @vdblink::io::File::readAllGridMetadata
  io::File::readAllGridMetadata@endlink methods to read just the
  grid metadata and transforms from a <TT>.vdb</TT> file.
- Fixed numerical precision issues in the
  @vdblink::tools::csgUnion csgUnion@endlink,
  @vdblink::tools::csgIntersection csgIntersection@endlink
  and @vdblink::tools::csgDifference csgDifference@endlink
  tools, and added toggles to optionally disable postprocess pruning.
- Fixed an issue in @c vdb_view with the ordering of GL vertex buffer calls.
  <I>[Contributed by Bill Katz]</I>
- Fixed an intermittent crash in the
  @vdblink::tools::ParticlesToLevelSet ParticlesToLevelSet@endlink tool,
  as well as a race condition that could cause data corruption.
- The @vdblink::tools::ParticlesToLevelSetAndId ParticlesToLevelSet@endlink
  tool and From Particles SOP can now transfer arbitrary point attribute
  values from the input particles to output voxels.
- Fixed a bug in the Convert SOP whereby the names of primitives
  were lost during conversion, and another bug that resulted in
  arithmetic errors when converting empty grids.
- Fixed a bug in the Combine SOP that caused the Operation selection
  to be lost.


@par
<B>Version 0.98.0</B> - <I>November 16 2012</I>
- @vdblink::tree::Tree Tree@endlink and
  @vdblink::math::Transform Transform@endlink objects (and
  @vdblink::Grid Grid@endlink objects in the context of Houdini SOPs)
  are now passed and accessed primarily by reference rather than by
  shared pointer.  See @subpage api_0_98_0 "Porting to OpenVDB 0.98.0"
  for details about this important API change.
  <I>[Contributed by SESI]</I>
- Reimplemented @vdblink::math::CoordBBox CoordBBox@endlink to address several
  off-by-one bugs related to bounding box dimensions.
- Fixed an off-by-one bug in @vdblink::Grid::evalActiveVoxelBoundingBox()
  evalActiveVoxelBoundingBox@endlink.
- Introduced the @vdblink::tree::LeafManager LeafManager@endlink class,
  which will eventually replace the
  @vdblink::tree::LeafArray LeafArray@endlink class.  @c LeafManager supports
  dynamic buffers stored as a structure of arrays (SOA), unlike @c LeafArray,
  which supports only static buffers stored as an array of structures (AOS).
- Improved the performance of the
  @vdblink::tools::LevelSetFilter LevelSetFilter@endlink and
  @vdblink::tools::LevelSetTracker LevelSetTracker@endlink tools by rewriting
  them to use the new @vdblink::tree::LeafManager LeafManager@endlink class.
- Added @vdblink::tree::Tree::setValueOnly() Tree::setValueOnly@endlink and
  @vdblink::tree::ValueAccessor::setValueOnly()
  ValueAccessor::setValueOnly@endlink methods, which change the value of
  a voxel without changing its active state, and
  @vdblink::tree::Tree::probeLeaf() Tree::probeLeaf@endlink and
  @vdblink::tree::ValueAccessor::probeLeaf() ValueAccessor::probeLeaf@endlink
  methods that return the leaf node that contains a given voxel (unless
  the voxel is represented by a tile).
- Added a @vdblink::tools::LevelSetAdvection LevelSetAdvection@endlink tool
  that propagates and tracks narrow-band level sets.
- Introduced a new @vdblink::tools::GridSampler GridSampler@endlink class
  that supports world-space (or index-space) sampling of grid values.
- Changed the interpretation of the
  @vdblink::math::NonlinearFrustumMap NonlinearFrustumMap@endlink's
  @em taper parameter to be the ratio of the near and far plane depths.
- Added a @c ParmFactory::setChoiceList() overload that accepts
  (@em token, @em label) string pairs, and a @c setDefault() overload that
  accepts an STL string.
- Fixed a crash in the Combine SOP in Copy B mode.
- Split the Level Set Filter SOP into three separate SOPs,
  Level Set Smooth, Level Set Reshape and Level Set Renormalize.
  When two or more of these nodes are connected in sequence, they interact
  to reduce memory usage: the last node in the sequence performs
  all of the operations in one step.
- The Advect Points SOP can now output polyline streamlines
  that trace the paths of the points.
- Added an option to the Analysis SOP to specify names for output grids.
- Added camera-derived frustum transform support to the Create SOP.


@par
<B>Version 0.97.0</B> - <I>October 18 2012</I>
- Added a narrow-band @vdblink::tools::LevelSetTracker level set
  interface tracking tool@endlink (up to fifth-order in space but currently
  only first-order in time, with higher temporal orders to be added soon).
- Added a @vdblink::tools::LevelSetFilter level set filter tool@endlink
  to perform unrestricted surface smoothing (e.g., Laplacian flow),
  filtering (e.g., mean value) and morphological operations (e.g.,
  morphological opening).
- Added adaptivity to the @vdblink::tools::VolumeToMesh
  level set meshing tool@endlink for faster mesh extraction with fewer
  polygons, without postprocessing.
- Added a @vdblink::tree::ValueAccessor::touchLeaf()
  ValueAccessor::touchLeaf@endlink method that creates (if necessary)
  and returns the leaf node containing a given voxel.  It can be used
  to preallocate leaf nodes over which to run parallel algorithms.
- Fixed a bug in @vdblink::Grid::merge() Grid::merge@endlink whereby
  active tiles were sometimes lost.
- Added @vdblink::tree::LeafManager LeafManager@endlink, which is similar
  to @vdblink::tree::LeafArray LeafArray@endlink but supports a
  dynamic buffer count and allocates buffers more efficiently.
  Useful for temporal integration (e.g., for level set propagation
  and interface tracking), @c LeafManager is meant to replace @c LeafArray,
  which will be deprecated in the next release.
- Added a @vdblink::tree::LeafNode::fill() LeafNode::fill@endlink method
  to efficiently populate leaf nodes with constant values.
- Added a @vdblink::tree::Tree::visitActiveBBox() Tree::visitActiveBBox@endlink
  method that applies a functor to the bounding boxes of all active tiles
  and leaf nodes and that can be used to improve the performance of
  ray intersection tests, rendering of bounding boxes, etc.
- Added a @vdblink::tree::Tree::voxelizeActiveTiles()
  Tree::voxelizeActiveTiles@endlink method to densify active tiles.
  While convenient and fast, this can produce large dense grids, so use
  it with caution.
- Repackaged @c Tree::pruneLevelSet() as a
  @vdblink::tree::Tree::pruneOp() Tree::pruneOp()@endlink-compatible
  functor.  @vdblink::tree::LevelSetPrune LevelSetPrune@endlink is a
  specialized @vdblink::tree::Tree::pruneInactive() pruneInactive@endlink
  for level-set grids and is used in interface tracking.
- Added a @vdblink::GridBase::pruneGrid() GridBase::pruneGrid@endlink method.
- Added a @vdblink::Grid::hasUniformVoxels() Grid:hasUniformVoxels@endlink
  method.
- Renamed @c tools::dilate to
  @vdblink::tools::dilateVoxels() dilateVoxels@endlink and improved its
  performance.  The new name reflects the fact that the current
  implementation ignores active tiles.
- Added a @vdblink::tools::resampleToMatch() tools::resampleToMatch@endlink
  function that resamples an input grid into an output grid with a
  different transform such that, after resampling, the input and output grids
  coincide, but the output grid's transform is preserved.
- Significantly improved the performance of depth-bounded value
  iterators (@vdblink::tree::Tree::ValueOnIter ValueOnIter@endlink,
  @vdblink::tree::Tree::ValueAllIter ValueAllIter@endlink, etc.)
  when the depth bound excludes leaf nodes.
- Exposed the value buffers inside leaf nodes with
  @vdblink::tree::LeafNode::buffer() LeafNode::buffer@endlink.
  This allows for very fast access (const and non-const) to voxel
  values using linear array offsets instead of @ijk coordinates. 
- In openvdb_houdini/UT_VDBTools.h, added operators for use with
  @c processTypedGrid that resample grids in several different ways.
- Added a policy mechanism to @c houdini_utils::OpFactory that allows for
  customization of operator names, icons, and Help URLs.
- Renamed many of the Houdini SOPs to make the names more consistent.
- Added an Advect Points SOP.
- Added a Level Set Filter SOP that allows for unrestricted surface
  deformations, unlike the older Filter SOP, which restricts surface
  motion to the initial narrow band.
- Added staggered vector sampling to the Sample Points SOP.
- Added a minimum radius threshold to the particle voxelization tool
  and SOP.
- Merged the Composite and CSG SOPs into a single Combine SOP.
- Added a tool and a SOP to efficiently generate narrow-band level set
  representations of spheres.
- In the Visualize SOP, improved the performance of tree topology
  generation, which is now enabled by default.


@par
<B>Version 0.96.0</B> - <I>September 24 2012</I>
- Fixed a memory corruption bug in the mesh voxelizer tool.
- Temporarily removed the optional clipping feature from the level set mesher.
- Added "Staggered Vector Field" to the list of grid classes in the Create SOP.


@par
<B>Version 0.95.0</B> - <I>September 20 2012</I>
- Added a quad @vdblink::tools::VolumeToMesh meshing@endlink tool for
  higher-quality level set meshing and updated the Visualizer SOP
  to use it.
- Fixed a precision error in the @vdblink::tools::MeshToVolume
  mesh voxelizer@endlink and improved the quality of inside/outside
  voxel classification.  Output grids are now also
  @vdblink::Grid::setGridClass() classified@endlink as either level sets
  or fog volumes.
- Modified the @vdblink::tools::GridResampler GridResampler@endlink
  to use the signed flood fill optimization only on grids that are
  tagged as level sets.
- Added a @vdblink::math::Quat quaternion@endlink class to the
  math library and a method to return the
  @vdblink::math::Mat3::trace trace@endlink of a @c Mat3.
- Fixed a bug in the
  @vdblink::tree::ValueAccessor::ValueAccessor(const ValueAccessor&)
  ValueAccessor@endlink copy constructor that caused the copy to reference
  the original.
- Fixed a bug in @vdblink::tree::RootNode::setActiveState()
  RootNode::setActiveState@endlink that caused a crash
  when marking a (virtual) background voxel as inactive.
- Added a @c Tree::pruneLevelSet method that is similar to but faster than
  @vdblink::tree::Tree::pruneInactive() pruneInactive@endlink
  for level set grids.
- Added fast leaf node voxel access
  @vdblink::tree::LeafNode::getValue(Index) const methods@endlink
  that index by linear offset (as returned by
  @vdblink::tree::LeafNode::ValueOnIter::pos() ValueIter::pos@endlink)
  instead of by @ijk coordinates.
- Added a @vdblink::tree::Tree::touchLeaf() Tree::touchLeaf@endlink
  method that can be used to preallocate a static tree topology over which
  to safely perform multithreaded processing.
- Added a grain size argument to @vdblink::tree::LeafArray::getRange()
  LeafArrary@endlink for finer control of parallelism.
- Modified the Makefile to make it easier to omit the <TT>doc</TT>,
  @c vdb_test and @c vdb_view targets.
- Added utility functions (in <TT>houdini/UT_VDBUtils.h</TT>) to convert
  between Houdini and OpenVDB matrix and vector types.
  <I>[Contributed by SESI]</I>
- Added accessors to @c GEO_PrimVDB that make it easier to directly access
  voxel data and that are used by the HScript volume expression functions
  in Houdini 12.5.  <I>[Contributed by SESI]</I>
- As of Houdini 12.1.77, the native transform SOP operates on OpenVDB
  primitives.  <I>[Contributed by SESI]</I>
- Added a Convert SOP that converts OpenVDB grids to Houdini volumes
  and vice-versa.


@par
<B>Version 0.94.1</B> - <I>September 7 2012</I>
- Fixed bugs in @vdblink::tree::RootNode RootNode@endlink and
  @vdblink::tree::InternalNode InternalNode@endlink @c setValue*() and
  @c fill() methods that could cause neighboring voxels to become inactive.
- Fixed a bug in
  @vdblink::tree::Tree::hasSameTopology() Tree::hasSameTopology@endlink
  that caused false positives when only active states and not values differed.
- Added a @vdblink::tree::Tree::hasActiveTiles() Tree::hasActiveTiles@endlink
  method.
- For better cross-platform consistency, substituted bitwise AND operations
  for right shifts in the @vdblink::tree::ValueAccessor ValueAccessor@endlink
  hash key computation.
- @c vdb_view no longer aborts when asked to surface a vector-valued
  grid&mdash;but it still doesn't render the surface.
- Made various changes for Visual C++ compatibility.
  <I>[Contributed by SESI]</I>
- Added an option to the MeshVoxelizer SOP to convert both open and
  closed surfaces to unsigned distance fields.
- The Filter SOP now allows multiple filters to be applied in
  user-specified order.


@par
<B>Version 0.94.0</B> - <I>August 30 2012</I>
- Added a @vdblink::Grid::topologyUnion() method@endlink to union
  just the active states of voxels from one grid with those of
  another grid of a possibly different type.
- Fixed an incorrect scale factor in the Laplacian diffusion
  @vdblink::tools::Filter::laplacian() filter@endlink.
- Fixed a bug in @vdblink::tree::Tree::merge() Tree::merge@endlink
  that could leave a tree with invalid value accessors.
- Added @vdblink::tree::TreeValueIteratorBase::setActiveState()
  TreeValueIteratorBase::setActiveState@endlink and deprecated
  @vdblink::tree::TreeValueIteratorBase::setValueOn setValueOn@endlink.
- Removed @c tools/FastSweeping.h.  It will be replaced with a much more
  efficient implementation in the near future.
- ZIP compression of <TT>.vdb</TT> files is now
  @vdblink::io::File::setCompressionEnabled() optional@endlink,
  but enabled by default.  <I>[Contributed by SESI]</I>
- Made various changes for Clang and Visual C++ compatibility.
  <I>[Contributed by SESI]</I>
- The MeshVoxelizer SOP can now transfer arbitrary point and primitive
  attribute values from the input mesh to output voxels.


@par
<B>Version 0.93.0</B> - <I>August 24 2012</I>
- Renamed symbols in math/Operators.h to avoid ambiguities that
  GCC&nbsp;4.4 reports as errors.
- Simplified the API for the stencil version of the
  closest-point transform @vdblink::math::CPT operator@endlink.
- Added logic to
  @vdblink::io::Archive::readGrid() io::Archive::readGrid@endlink
  to set the grid name metadata from the descriptor if the metadata
  doesn't already exist.
- Added guards to prevent nesting of @c openvdb_houdini::Interrupter::start()
  and @c end() calls.


@par
<B>Version 0.92.0</B> - <I>August 23 2012</I>
- Added a Laplacian diffusion
  @vdblink::tools::Filter::laplacian() filter@endlink.
- Fixed a bug in the initialization of the sparse contour tracer
  that caused mesh-to-volume conversion to fail in certain cases.
- Fixed a bug in the curvature stencil that caused mean curvature
  filtering to produce wrong results.
- Increased the speed of the
  @vdblink::tools::GridTransformer GridTransformer@endlink
  by as much as 20% for fog volumes.
- Added optional pruning to the Resample SOP.
- Modified the PointSample SOP to allow it to work with ungrouped,
  anonymous grids.
- Fixed a crash in the LevelSetNoise SOP.


@par
<B>Version 0.91.0</B> - <I>August 16 2012</I>
- @vdblink::tools::GridTransformer tools::GridTransformer@endlink
  and @vdblink::tools::GridResampler tools::GridResampler@endlink
  now correctly (but not yet efficiently) process tiles in sparse grids.
- Added an optional @vdblink::CopyPolicy CopyPolicy@endlink argument
  to @vdblink::GridBase::copyGrid() GridBase::copyGrid@endlink
  and to @vdblink::Grid::copy() Grid::copy@endlink that specifies
  whether and how the grid's tree should be copied.
- Added a @vdblink::GridBase::newTree() GridBase::newTree@endlink
  method that replaces a grid's tree with a new, empty tree of the
  correct type.
- Fixed a crash in
  @vdblink::tree::Tree::setValueOff(const Coord& xyz, const ValueType& value)
  Tree::setValueOff@endlink when the new value was equal to the
  background value.
- Fixed bugs in @vdblink::tree::Tree::prune() Tree::prune@endlink
  that could result in output tiles with incorrect active states.
- Added @c librt to the link dependencies to address build failures
  on Ubuntu systems.
- Made various small changes to the Makefile and the source code
  that should help with Mac OS&nbsp;X compatibility.
- The Composite and Resample SOPs now correctly copy the input grid's
  metadata to the output grid.


@par
<B>Version 0.90.1</B> - <I>August 7 2012</I>
- Fixed a bug in the
  @vdblink::math::BBox::getCenter() BBox::getCenter()@endlink method.
- Added missing header files to various files.
- @vdblink::io::File::NameIterator::gridName()
  io::File::NameIterator::gridName()@endlink now returns a unique name
  of the form <TT>"name[1]"</TT>, <TT>"name[2]"</TT>, etc. if a file
  contains multiple grids with the same name.
- Fixed a bug in the Writer SOP that caused grid names to be discarded.
- The Resample SOP now correctly sets the background value of the
  output grid.


@par
<B>Version 0.90.0</B> - <I>August 3 2012</I> (initial public release)
- Added a basic GL viewer for OpenVDB files.
- Greatly improved the performance of two commonly-used @c Tree methods,
  @vdblink::tree::Tree::evalActiveVoxelBoundingBox()
  evalActiveVoxelBoundingBox()@endlink
  and @vdblink::tree::Tree::memUsage() memUsage()@endlink.
- Eliminated the @c GridMap class.  File I/O now uses STL containers
  of grid pointers instead.
- Refactored stencil-based tools (Gradient, Laplacian, etc.) and rewrote
  some of them for generality and better performance.  Most now behave
  correctly for grids with nonlinear index-to-world transforms.
- Added a @link FiniteDifference.h library@endlink of index-space finite
  difference operators.
- Added a @vdblink::math::Hermite "Hermite"@endlink grid type that compactly
  stores each voxel's upwind normals and can be used to convert volumes
  to and from polygonal meshes.
- Added a @link PointScatter.h tool@endlink (and a Houdini SOP)
  to scatter points randomly throughout a volume.

*/
