IECoreUSD : Use / for resolved paths.

On Windows, the result of USD's `GetResolvedPath()` method returns the
resolved path using `\` between directories. This can cause problems
when doing string substition on a resolved path since the `\` will be
interpreted as the start of an escape character. Using `/` also
conforms to Cortex's standard of always using `/` for paths because they
work on all operating systems.

Author: ericmehl

Changes

@@ -9,6 +9,7 @@ Fixes
   - Fixed loading of skinned facevarying normals.
   - `lightLink` and `shadowLink` collections on UsdLuxLightAPI are no longer treated as sets.
 - Version.h : Fixed `*Version()` functions to return the runtime version of the library, not the version that client code was compiled with. Use the `CORTEX_*_VERSION` macros for compile time checks.
+- IECoreUSD : Asset and volume paths now use `/` in the resolved path on all operating systems. This behavior can be disabled by setting the `IECOREUSD_FORCE_ASSET_PATH_FORWARD_SLASH` environment variable to a value of `0`.
 
 10.5.9.2 (relative to 10.5.9.1)
 ========

contrib/IECoreUSD/src/IECoreUSD/DataAlgo.cpp

@@ -49,6 +49,10 @@ IECORE_POP_DEFAULT_VISIBILITY
 
 #include "boost/unordered_map.hpp"
 
+#ifdef _MSC_VER
+#include <filesystem>
+#endif
+
 using namespace std;
 using namespace pxr;
 using namespace IECore;
@@ -92,6 +96,19 @@ GeometricData::Interpretation interpretation( TfToken role )
 	return GeometricData::None;
 }
 
+#ifdef _MSC_VER
+
+static const bool g_forceAssetPathForwardSlash = []() -> bool {
+	const char *c = getenv( "IECOREUSD_FORCE_ASSET_PATH_FORWARD_SLASH" );
+	if( !c )
+	{
+		return true;
+	}
+	return strcmp( c, "0" );
+}();
+
+#endif
+
 } // namespace
 
 
@@ -142,9 +159,16 @@ IECore::DataPtr dataFromArray( const pxr::VtValue &value, GeometricData::Interpr
 
 IECore::DataPtr dataFromSdfAssetPath( const SdfAssetPath &assetPath, const pxr::UsdAttribute *attribute = nullptr )
 {
-	if( assetPath.GetResolvedPath().size() || !assetPath.GetAssetPath().size() || !attribute )
+
+#ifdef _MSC_VER
+	const std::string p = g_forceAssetPathForwardSlash ? std::filesystem::path( assetPath.GetResolvedPath() ).generic_string() : assetPath.GetResolvedPath();
+#else
+	const std::string p = assetPath.GetResolvedPath();
+#endif
+
+	if( p.size() || !assetPath.GetAssetPath().size() || !attribute )
 	{
-		return new StringData( assetPath.GetResolvedPath() );
+		return new StringData( p );
 	}
 
 	// Path resolution failed, for a couple of possible reasons :
@@ -168,9 +192,16 @@ IECore::DataPtr dataFromSdfAssetPath( const SdfAssetPath &assetPath, const pxr::
 			spec->GetLayer()->GetNumTimeSamplesForPath( spec->GetPath() )
 		)
 		{
+#ifdef _MSC_VER
+			const std::string result = SdfComputeAssetPathRelativeToLayer( spec->GetLayer(), assetPath.GetAssetPath() );
+			return new StringData(
+				g_forceAssetPathForwardSlash ? std::filesystem::path( result ).generic_string() : result
+			);
+#else
 			return new StringData(
 				SdfComputeAssetPathRelativeToLayer( spec->GetLayer(), assetPath.GetAssetPath() )
 			);
+#endif
 		}
 	}
 

contrib/IECoreUSD/src/IECoreUSD/VolumeAlgo.cpp

@@ -32,11 +32,13 @@
 //
 //////////////////////////////////////////////////////////////////////////
 
+#include "IECoreUSD/DataAlgo.h"
 #include "IECoreUSD/ObjectAlgo.h"
 
 #include "IECoreVDB/VDBObject.h"
 
 #include "IECore/MessageHandler.h"
+#include "IECore/SimpleTypedData.h"
 
 IECORE_PUSH_DEFAULT_VISIBILITY
 #include "pxr/usd/usdVol/volume.h"
@@ -96,9 +98,8 @@ IECore::ObjectPtr readVolume( pxr::UsdVolVolume &volume, pxr::UsdTimeCode time,
 			continue;
 		}
 
-		SdfAssetPath fieldAssetPath;
-		fieldAsset.GetFilePathAttr().Get( &fieldAssetPath, time );
-		const std::string fieldFileName = fieldAssetPath.GetResolvedPath();
+		ConstDataPtr fieldFileNameData = DataAlgo::fromUSD( fieldAsset.GetFilePathAttr(), time );
+		const std::string fieldFileName = static_cast<const StringData *>( fieldFileNameData.get() )->readable();
 
 		if( fileName.empty() )
 		{

contrib/IECoreUSD/test/IECoreUSD/USDSceneTest.py

@@ -32,6 +32,8 @@
 #
 ##########################################################################
 
+import IECore
+
 import importlib
 import os
 import math
@@ -4371,5 +4373,30 @@ def testWriteToOpenScene( self ) :
 		with self.assertRaisesRegex( RuntimeError, f"USDScene : Failed to open USD stage : '{fileName}'" ) :
 			IECoreScene.SceneInterface.create( fileName, IECore.IndexedIO.OpenMode.Write )
 
+	def testAssetPathSlashes ( self ) :
+
+		root = IECoreScene.SceneInterface.create(
+			os.path.join( os.path.dirname( __file__ ), "data", "assetPathAttribute.usda" ),
+			IECore.IndexedIO.OpenMode.Read
+		)
+		xform = root.child( "xform" )
+
+		self.assertEqual( xform.attributeNames(), [ "render:testAsset" ] )
+		self.assertNotIn( "\\", xform.readAttribute( "render:testAsset", 0 ).value )
+		self.assertTrue( pathlib.Path( xform.readAttribute( "render:testAsset", 0 ).value ).is_file() )
+
+	@unittest.skipIf( not haveVDB, "No IECoreVDB" )
+	def testUsdVolVolumeSlashes( self ) :
+
+		import IECoreVDB
+
+		fileName = os.path.dirname( __file__ ) + "/data/volume.usda"
+		root = IECoreScene.SceneInterface.create( fileName, IECore.IndexedIO.OpenMode.Read )
+		child = root.child( "volume" )
+
+		vdbObject = child.readObject( 0 )
+		self.assertNotIn( "\\", vdbObject.fileName() )
+		self.assertTrue( pathlib.Path( vdbObject.fileName() ).is_file() )
+
 if __name__ == "__main__":
 	unittest.main()