From 16a16d9b3e3bdb828558d663475d286f01f6afdb Mon Sep 17 00:00:00 2001
From: Alex <boberfly@gmail.com>
Date: Sat, 20 Apr 2024 13:47:46 +1000
Subject: [PATCH] IECoreUSD : Alembic referenced in a USD stage places the
 indices of an indexed primitive variable into an attribute

---
 .../IECoreUSD/test/IECoreUSD/USDSceneTest.py  |  24 ++++++++++++++++++
 .../test/IECoreUSD/data/alembicIndices.abc    | Bin 0 -> 3222 bytes
 .../test/IECoreUSD/data/alembicIndices.usda   |   8 ++++++
 3 files changed, 32 insertions(+)
 create mode 100644 contrib/IECoreUSD/test/IECoreUSD/data/alembicIndices.abc
 create mode 100644 contrib/IECoreUSD/test/IECoreUSD/data/alembicIndices.usda

diff --git a/contrib/IECoreUSD/test/IECoreUSD/USDSceneTest.py b/contrib/IECoreUSD/test/IECoreUSD/USDSceneTest.py
index 5bd4576222..7893c311b9 100644
--- a/contrib/IECoreUSD/test/IECoreUSD/USDSceneTest.py
+++ b/contrib/IECoreUSD/test/IECoreUSD/USDSceneTest.py
@@ -4001,5 +4001,29 @@ def testRoundTripArnoldLight( self ) :
 		self.assertIn( "__lights", root.setNames() )
 		self.assertEqual( root.readSet( "__lights" ), IECore.PathMatcher( [ "/light" ] ) )
 
+	def testAlembicIndices( self ) :
+
+		root = IECoreScene.SceneInterface.create( os.path.dirname( __file__ ) + "/data/alembicIndices.usda", IECore.IndexedIO.OpenMode.Read )
+
+		cube = root.child( "cube" )
+		self.assertEqual( cube.attributeNames(), [] )
+		self.assertFalse( cube.hasAttribute( "primvars:custom:indices" ) )
+
+		primitive = cube.readObject( 1.0 )
+		self.assertEqual(
+			set( primitive.keys() ),
+			{ "P", "N", "uv", "custom" }
+		)
+		comparison = IECoreScene.PrimitiveVariable(
+			IECoreScene.PrimitiveVariable.Interpolation.FaceVarying,
+			IECore.Color3fVectorData(
+				[ imath.Color3f( 1, 0, 0 ), imath.Color3f( 0, 1, 0 ), imath.Color3f( 0, 0, 1 ),
+				imath.Color3f( 1, 1, 0 ), imath.Color3f( 0, 1, 1 ), imath.Color3f( 1, 1, 1 ) ]
+			),
+			IECore.IntVectorData( [ 1, 1, 1, 1, 4, 4, 4, 4, 0, 0, 0, 0, 5, 5, 5, 5, 2, 2, 2, 2, 3, 3, 3, 3 ] )
+		)
+		self.assertEqual( primitive["custom"], comparison )
+		self.assertEqual( primitive["custom"].indices(), comparison.indices() )
+
 if __name__ == "__main__":
 	unittest.main()
diff --git a/contrib/IECoreUSD/test/IECoreUSD/data/alembicIndices.abc b/contrib/IECoreUSD/test/IECoreUSD/data/alembicIndices.abc
new file mode 100644
index 0000000000000000000000000000000000000000..dac2ca9e078bdba5a8cbe0dbbf59277689ed1365
GIT binary patch
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diff --git a/contrib/IECoreUSD/test/IECoreUSD/data/alembicIndices.usda b/contrib/IECoreUSD/test/IECoreUSD/data/alembicIndices.usda
new file mode 100644
index 0000000000..b71d112909
--- /dev/null
+++ b/contrib/IECoreUSD/test/IECoreUSD/data/alembicIndices.usda
@@ -0,0 +1,8 @@
+#usda 1.0
+
+def Mesh "cube" (
+    references = @./alembicIndices.abc@
+)
+{
+}
+