Merge release v20.08

.gitignore

@@ -1 +1,4 @@
 .p4*
+.DS_Store
+.AppleDouble
+

BUILDING.md

@@ -111,6 +111,14 @@ that depend on GL, including:
 - usdview
 - Hydra GL imaging
 
+##### Metal
+
+To build USD with Metal enabled requires macOS Mojave (10.14) or newer.
+Support for Metal can optionally be disabled by specifying the cmake flag
+```PXR_ENABLE_METAL_SUPPORT=FALSE```.  This will skip components and libraries
+that depend on Metal, including:
+- Hydra imaging
+
 ##### OSL (OpenShadingLanguage)
 
 Support for OSL is disabled by default, and can optionally be enabled by

CHANGELOG.md

@@ -1,5 +1,202 @@
 # Change Log
 
+## [20.08] - 2020-07-21
+
+### Build
+- The "master" branch on GitHub has been renamed "release".
+- Improved error handling when building the RenderMan plugin. (Issue #1054)
+
+- Various fixes and changes to build_usd.py:
+  - Added `--tools` and `--no-tools` options.
+  - Updated OpenImageIO (2.1.16.0) and MaterialX (1.37.1) dependencies.
+  - Specifying `--embree` will now build the Embree library. The
+    `--embree-location` parameter has been removed.
+  - CMake 3.14 is now required on Windows to support boost 1.70+.
+  - Python 3.8 on Windows now causes an error, as USD does not support
+    this version on Windows.
+  - Improved handling of boost build failures.
+  - Fixed locale decoding errors. (Issue #1165)
+  - Fixed incorrect detection of Draco library. (PR #1239)
+
+### USD
+- Added support for "future division" in Python 2 to aid transition to Python 3.
+
+- Added ArResolver::CreatePathForLayer to allow users to customize behavior
+  when writing a layer. SdfLayer now uses this method instead of creating a
+  directory, which was not appropriate for non-filesystem uses. (Issue #1148)
+
+- Added SdfReference::IsInternal. (PR #1204)
+- Added fallback prim types feature, allowing clients to specify alternative
+  schemas to use if a schema can't be found. See documentation for more details.
+- Added UsdPrim::ApplyAPI, RemoveAPI, AddAppliedSchemas,
+  and RemoveAppliedSchemas. (Issue #1218)
+- Added Python __repr__ for generated schemas.
+- Added methods to UsdGeomPrimvar for processing property names.
+- Added methods to UsdGeomPrimvarsAPI for creating, removing, and blocking
+  primvars. (Issue #1100)
+- Improved documentation for UsdVol schema domain. (PR #1203)
+- Improved documentation for UsdGeomMesh. (PR #1254)
+- Improved diagnostic messages for plugin registration and loading.
+
+- Plugin search paths in PXR_PLUGINPATH_NAME can now be a symlink. Paths are
+  now processed in order to ensure plugins in earlier entries take priority
+  over those in later entries.
+
+- Replaced SdrShaderNode::GetSourceURI and GetResolvedSourceURI with
+  GetResolvedDefinitionURI and GetResolvedImplementationURI to properly
+  represent RenderMan C++ shaders.
+
+- Time sample times from layers whose timeCodesPerSecond value differ from
+  the UsdStage are now automatically scaled to match. This can be disabled
+  by setting the PCP_DISABLE_TIME_SCALING_BY_LAYER_TCPS environment variable,
+  but we expect to remove this in a future release.
+
+- Significant changes and additions to value clips functionality. See
+  documentation for more details:
+  - Added support for jump discontinuities in clip times metadata to encode
+    looping behaviors.
+  - The clip manifest is now used to determine which attributes have values
+    in clips. The manifest will be generated in-memory at runtime if one
+    hasn't been specified.
+  - Value resolution will no longer fall through to weaker layers if a clip
+    does not have values for an attribute declared in the manifest. In these
+    cases, the value may come from the default value authored in the manifest
+    or (optionally) be interpolated from surrounding clips.
+  - Removed support for legacy value clips metadata.
+  - Fixed numerous bugs, including incorrect time samples when reversing
+    clips. (Issue #1116)
+
+- Changed the strength ordering of entries in the apiSchemas metadata to be
+  strongest-to-weakest, matching the ordering of references and other fields.
+- Constructing a UsdGeom::XformOp with an invalid attribute is no longer a
+  coding error for consistency with other schemas and objects.
+- Deprecated many schemas in UsdRi in preparation for modernization efforts
+  in a future release.
+- Removed support for deprecated "hermite" and "power" basis from UsdGeomCurves.
+- Fixed crash when removing many entries from an SdfPathTable. (PR #1172)
+- Fixed compile error due to missing virtual destructor for
+  PcpDynamicFileFormatInterface. (PR #1156)
+- Fixed type conversions when setting metadata values using dictionaries
+  in Python. (Issue #813)
+- Fixed handling of stage metadata and session layer muting in UsdStage.
+- Fixed UsdFlattenLayerStack to handle mismatched attribute types and
+  time-sampled asset paths. (PR #1169)
+- Fixed undefined behavior issue with iterator comparisons. (Issue #1146)
+- Fixed regression in handling of inherited bindings in UsdSkelCache.
+- Fixed crash in UsdSkelBakeSkinning. (PR #1213)
+
+### Imaging
+- Updated minimum required version of OpenGL to v4.5.
+
+- Added new texture system to Storm. This enables multi-threaded texture
+  loading, uses Hgi, and frees the scene delegate from having to load
+  textures. In a performance test using Nvidia's Attic scene, time to first
+  image dropped by ~90%, from 115s to 10s.
+
+- Added first iteration of HgiMetal, a Metal-based Hgi implementation for
+  Apple platforms. Currently, Hgi is used in several Hydra tasks to perform
+  tasks like blitting, the goal is to slowly integrate Hgi in Storm.
+
+- Numerous updates to Hgi:
+  - Added HgiInterop to exchange rendered results between GL-GL or Metal-GL.
+  - Added HgiSampler to represent texture samplers.
+  - Added HgiComputeCmds to issue compute commands.
+  - Added HgiBlitCmds for mipmap generation and GPU-GPU copy.
+  - Added SRGB format and removed unsupported 24-bit formats.
+  - Added GetRawResource function to various resource objects to expose
+    low-level resource handles.
+
+- Added garbage collection to HgiGL for proper handling of resource destruction.
+- Added HdRendererPluginHandle, an RAII object for managing plugin lifetimes.
+- Added HdxAovInputTask which takes HdRenderBuffer and (if needed) uploads
+  it to the GPU as HgiTexture.
+- Added support for down-sampling volumes in Storm.
+- Improved performance of volumes in Storm by not re-creating the entire
+  volume shader when fields are animated.
+- Added support for UsdTransform2d node in Storm. (Issue #1207)
+- Added support for UsdUVTexture scale and bias in Storm. (Issue #1129)
+- Added USDIMAGINGGL_ENGINE_DEBUG_SCENE_DELEGATE_ID environment variable to
+  specify scene delegate ID for debugging. (Issue #1093)
+- Changed default version of HdSceneDelegate::GetScenePrimPath to strip
+  delegate ID.
+- Replaced obsolete GL_GENERATE_MIPMAP with glGenerateMipmap. (Issue #1171)
+- Added support for uint16 type for GL textures and OpenImageIO. (PR #1212)
+- Restructured OpenImageIO support as a plugin to Glf. (PR #1214)
+- Converted common Hydra tasks (e.g. HdxColorCorrectionTask, HdxPresentTask,
+  HdxColorizeSelectionTask) to use Hgi.
+- Renamed HdxProgressiveTask to HdxTask.
+- Storm now uses Hgi for buffers, shaders, and programs instead of OpenGL.
+- HdStResourceRegistry is instantiated once per Hgi instance in Storm.
+- Unshared computation BAR are reused when possible. (Issue #1083)
+- Improved handling of invalid cases in several areas. (PR #1232, PR #1201)
+- Improved performance of UsdImagingDelegate::SetTime. (Issue #1166)
+- Improved performance for displaying meshes with large numbers of geometry
+  subsets. (PR #1170)
+- Normals are ignored on skinned meshes so they are computed post-skinning.
+- Inherited UsdSkel bindings are now respected.
+- Allow HdStRenderBuffer::Resolve() to change the size of the image. (PR #1236)
+- Removed "catmark" token in pxOsd in favor of "catmullClark".
+- Removed UsdImagingGLMaterialTextureAdapter, UsdImagingGLDomeLightAdapter,
+  GlfVdbTexture[Container], and GlfTextureContainer, which are unneeded with
+  the new texture system.
+- Removed unused HdxColorizeTask and HdxFullscreenShaderGL.
+- Removed HdWrapLegacyClamp, which corresponded to the deprecated GL_CLAMP.
+- Removed uses of HdStGLSLProgram as part of a new strategy to create these
+  via HdStResourceRegistry (since it has access to Hgi).
+- Removed transform feedback from non-instanced GPU culling in Storm.
+- Fixed incorrect handling of buffer array resizing to 0 elements. (Issue #1230)
+- Fixed memory regression when calling UsdImagingDelegate::SampleTransform
+  and SamplePrimvar.
+- Fixed error in UsdImaging when changing from a time where a mesh provided
+  points or normals to a time that does not.
+- Fixed potential deadlocks if plugins were loaded at various points in
+  UsdImagingGLEngine.
+- Fixed error when processing skinned prim with no joint influences.
+- Fixed change processing issue with native instanced prims. (Issue #1163)
+- Fixed handling of widths primvar with no value.
+- Fixed "IsFlipped" computation for native instanced prims. (Issue #1190)
+- Fixed crash when updating a removed primvar. (PR #1223)
+- Fixed crash when reparenting an instance root. (Issue #1245)
+- Fixed various issues with cards prims, including a crash issue. (Issue #1210)
+- Fixed selection encoding/decoding of invisible native instances.
+- Fixed invalidation when changing the "purpose" attribute. (Issue #1243)
+
+### usdview
+- Added "Prototypes" pick mode that selects the prototype for a picked gprim
+  in a PointInstancer and highlights the picked instance.
+- Reverted "Prims" and "Instances" pick modes to original behavior of selecting
+  the root boundable of the picked object. (Issue #1196)
+- Fixed "Reopen Stage" when usdview was launched with `--norender`. (PR #1192)
+- Fixed camera guide and reticles rendering on high DPI displays.
+
+### Alembic Plugin
+- Fixed conversion of mesh subdivision interpolation options between
+  UsdGeomMesh and AbcGeom's ISubD and OSubD schemas. (PR #1246)
+
+### Embree Plugin
+- Removed support for Embree 2.0. The HdEmbree plugin now requires Embree 3.
+
+### MaterialX Plugin
+- Added support for MaterialX 1.37 and deprecated support for 1.36. We
+  anticipate requiring 1.37 in a future release.
+- MaterialX "vectorN" datatypes are now translated to USD "floatN" datatypes.
+- Changed default output name from "result" to "out" to match conventions
+  in MaterialX specification.
+- Fixed test issue found during Python 3 work. (PR #1161)
+
+### RenderMan Plugin
+- Added support for arbitrary numbers of AOVs in HdPrman.
+- Removed deprecated RenderMan 22 Hydra plugin.
+
+- Material processing now uses SdrShaderNode::GetResolvedImplementationURI to
+  locate shaders, which allows it consume shaders identified via 
+  UsdShadeShader's info:sourceAsset property.
+
+- Modified UsdVol support to allow easier extensions with custom volume plugin
+  for RenderMan.
+- Fixed calculation of specularFaceColor in UsdPreviewSurfaceParameters.osl
+  to better match the spec.
+
 ## [20.05] - 2020-04-13
 
 This release includes initial support for Python 3. Many thanks to our

CMakeLists.txt

@@ -44,8 +44,16 @@ pxr_toplevel_prologue()
 add_subdirectory(pxr)
 add_subdirectory(extras)
 
-if (${PXR_BUILD_PRMAN_PLUGIN})
-    add_subdirectory(third_party/renderman-${RENDERMAN_VERSION_MAJOR})
+if (PXR_BUILD_PRMAN_PLUGIN)
+    set(prmanPluginPath "third_party/renderman-${RENDERMAN_VERSION_MAJOR}")
+
+    get_filename_component(prmanPluginAbsPath "${prmanPluginPath}" ABSOLUTE)
+    if (EXISTS "${prmanPluginAbsPath}")
+        add_subdirectory("${prmanPluginPath}")
+    else()
+        message(FATAL_ERROR "No RenderMan plugin available for "
+                "RenderMan ${RENDERMAN_VERSION_MAJOR}")
+    endif()
 endif()
 
 if (PXR_BUILD_DOCUMENTATION)

LICENSE.txt

@@ -383,7 +383,7 @@ LZ4
 ============================================================
 
 LZ4 - Fast LZ compression algorithm
-Copyright (C) 2011-2017, Yann Collet.
+Copyright (C) 2011-present, Yann Collet.
 
 BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)