OpenVDB Version History
=======================

Version 0.102.0 - December 13 2012
    - Added tools::compReplace(), which copies the active values of one grid
      into another, and added a "Replace A With Active B" mode to the
      Combine SOP.
    - Grid::signedFloodFill() 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.

Version 0.101.1 - December 11 2012 (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.

Version 0.101.0 - December 6 2012 (DWA internal release)
    - Partially reverted the Grid's tree and transform 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 shared pointer accessors.
    - Restructured the mesh to volume converter 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 getNodeBoundingBox() method to RootNode, InternalNode
      and LeafNode that returns the index space spanned by a node.
    - Made various changes for Visual C++ compatibility.
      [Contributed by SESI]
    - 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.

Version 0.100.0 - November 30 2012 (DWA internal release)
    - Greatly improved the performance of the level set to fog volume
      converter.
    - Improved the performance of the median filter and of level set
      CSG operations.
    - Reintroduced Tree::pruneLevelSet(), a specialized pruneInactive()
      for level-set grids.
    - Added utilities to the 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 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.

Version 0.99.0 - November 21 2012
    - Added Grid methods that return non-const Tree and Transform
      references without triggering deep copies, as well as const
      methods that return const shared pointers.
    - Added Grid methods to populate a grid's metadata with statistics
      like the active voxel count, and to retrieve that metadata.
      By default, statistics are now computed and added to grids
      whenever they are written to .vdb files.
    - Added io::File::readGridMetadata() and io::File::readAllGridMetadata()
      methods to read just the grid metadata and transforms from a .vdb file.
    - Fixed numerical precision issues in the csgUnion, csgIntersection
      and csgDifference tools, and added toggles to optionally disable
      postprocess pruning.
    - Fixed an issue in vdb_view with the ordering of GL vertex buffer calls.
      [Contributed by Bill Katz]
    - Fixed an intermittent crash in the ParticlesToLevelSet tool,
      as well as a race condition that could cause data corruption.
    - The ParticlesToLevelSet 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
      an arithmetic error when converting an empty grid.
    - Fixed a bug in the Combine SOP that caused the Operation selection
      to be lost.

Version 0.98.0 - November 16 2012
    - Tree and Transform objects (and Grid objects in the context of
      Houdini SOPs) are now passed and accessed primarily by reference
      rather than by shared pointer.  See the online documentation for
      details about this important API change.
      [Contributed by SESI]
    - Reimplemented CoordBBox to address several off-by-one bugs
      related to bounding box dimensions.
    - Fixed an off-by-one bug in Grid::evalActiveVoxelBoundingBox().
    - Introduced the LeafManager class, which will eventually replace the
      LeafArray class.  LeafManager supports dynamic buffers stored as
      a structure of arrays (SOA), unlike LeafArray, which supports only
      static buffers stored as an array of structures (AOS).
    - Improved the performance of the LevelSetFilter and LevelSetTracker
      tools by rewriting them to use the new LeafManager class.
    - Added Tree and ValueAccessor setValueOnly() methods, which change
      the value of a voxel without changing its active state, and
      Tree and ValueAccessor probeLeaf() methods that return the leaf node
      that contains a given voxel (unless the voxel is represented by a tile).
    - Added a LevelSetAdvection tool that propagates and tracks
      narrow-band level sets.
    - Introduced a new GridSampler class that supports world-space
      (or index-space) sampling of grid values.
    - Changed the interpretation of the NonlinearFrustumMap's taper
      parameter to be the ratio of the near and far plane depths.
    - Added a ParmFactory::setChoiceList() overload that accepts
      (token, label) string pairs, and a 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.

Version 0.97.0 - October 18 2012
    - Added a narrow-band level set interface tracking tool (up to
      fifth-order in space but currently only first-order in time,
      with higher temporal orders to be added soon).
    - Added a level set filter tool 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 level set meshing tool for faster mesh
      extraction with fewer polygons, without postprocessing.
    - Added a ValueAccessor::touchLeaf() 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 Grid::merge() whereby active tiles were sometimes lost.
    - Added LeafManager, which is similar to LeafArray but supports a
      dynamic buffer count and allocates buffers more efficiently.
      Useful for temporal integration (e.g., for level set propagation
      and interface tracking), LeafManager is meant to replace LeafArray,
      which will be deprecated in the next release.
    - Added a LeafNode::fill() method to efficiently populate leaf nodes
      with constant values.
    - Added a Tree::visitActiveBBox() 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 Tree::voxelizeActiveTiles() method to densify active tiles.
      While convenient and fast, this can produce large dense grids,
      so use it with caution.
    - Repackaged Tree::pruneLevelSet() as a Tree::pruneOp()-compatible
      functor.  LevelSetPrune is a specialized pruneInactive() for
      level-set grids and is used in interface tracking.
    - Added a GridBase::pruneGrid() method.
    - Added a Grid:hasUniformVoxels() method.
    - Renamed tools::dilate() to tools::dilateVoxels() and improved its
      performance.  The new name reflects the fact that the current
      implementation ignores active tiles.
    - Added a tools::resampleToMatch() 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 (ValueOnIter, ValueAllIter, etc.) when the depth bound
      excludes leaf nodes.
    - Exposed the value buffers inside leaf nodes with LeafNode::buffer().
      This allows for very fast access (const and non-const) to voxel
      values using linear array offsets instead of (i,j,k) coordinates. 
    - In openvdb_houdini/UT_VDBTools.h, added operators for use with
      processTypedGrid() that resample grids in several different ways.
    - Added a policy mechanism to 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.

Version 0.96.0 - September 24 2012
    - 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.

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

Version 0.94.1 - September 7 2012
    - Fixed bugs in RootNode and InternalNode setValue*() and fill() methods
      that could cause neighboring voxels to become inactive.
    - Fixed a bug in Tree::hasSameTopology() that caused false positives
      when only active states and not values differed.
    - Added a Tree::hasActiveTiles() method.
    - For better cross-platform consistency, substituted bitwise AND
      operations for right shifts in the ValueAccessor hash key computation.
    - vdb_view no longer aborts when asked to surface a vector-valued
      grid--but it still doesn't render the surface.
    - Made various changes for Visual C++ compatibility.
      [Contributed by SESI]
    - 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.

Version 0.94.0 - August 30 2012
    - Added a method 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 filter.
    - Fixed a bug in Tree::merge that could leave a tree with invalid
      value accessors.
    - Added TreeValueIteratorBase::setActiveState() and deprecated setValueOn().
    - Removed tools/FastSweeping.h.  It will be replaced with a much more
      efficient implementation in the near future.
    - ZIP compression of .vdb files is now optional, but enabled by default.
      [Contributed by SESI]
    - Made various changes for Clang and Visual C++ compatibility.
      [Contributed by SESI]
    - The MeshVoxelizer SOP can now transfer arbitrary point and
      primitive attribute values from the input mesh to output voxels.

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


Version 0.92.0 - August 23 2012
    - Added a Laplacian diffusion filter.
    - 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 GridTransformer 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.

Version 0.91.0 - August 16 2012
    - tools::GridTransformer and tools::GridResampler now correctly
      (but not yet efficiently) process tiles in sparse grids.
    - Added an optional CopyPolicy argument to GridBase::copyGrid()
      and to Grid::copy() that specifies whether and how the grid's tree
      should be copied.
    - Added a GridBase::newTree() method that replaces a grid's tree with
      a new, empty tree of the correct type.
    - Fixed a crash in Tree::setValueOff() when the new value was equal to
      the background value.
    - Fixed bugs in Tree::prune() that could result in output tiles with
      incorrect active states.
    - Added 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 X compatibility.
    - The Composite and Resample SOPs now correctly copy the input grid's
      metadata to the output grid.

Version 0.90.1 - August 7 2012
    - Fixed a bug in the BBox::getCenter() method.
    - Added missing header files to various files.
    - io::File::NameIterator::gridName() now returns a unique name of the
      form "name[1]", "name[2]", 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.

Version 0.90.0 - August 3 2012 (initial public release)
    - Added a basic GL viewer for OpenVDB files.
    - Greatly improved the performance of two commonly-used Tree methods,
      evalActiveVoxelBoundingBox() and memUsage().
    - Eliminated the 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 library of index-space finite difference operators.
    - Added a "Hermite" grid type that compactly stores each voxel's upwind
      normals and can be used to convert volumes to and from polygonal meshes.
    - Added a tool (and a Houdini SOP) to scatter points randomly throughout
      a volume.

