EMSUSD-671 fix reloading scene with layers saved in the Maya scene

lib/mayaUsd/nodes/proxyShapeBase.cpp

@@ -940,8 +940,18 @@ MStatus MayaUsdProxyShapeBase::computeInStageDataCached(MDataBlock& dataBlock)
 
                 SdfLayerRefPtr rootLayer
                     = sharableStage ? computeRootLayer(dataBlock, fileString) : nullptr;
-                if (nullptr == rootLayer)
+                if (nullptr == rootLayer) {
                     rootLayer = SdfLayer::FindOrOpen(fileString);
+                } else {
+                    // When reloading a Maya scene in which the root layer was saved in
+                    // the scene, the root layer will be anonymous. In order for the next
+                    // compute to find the root layer again, we need to set it as the
+                    // _anonymousRootLayer, as done below when creating a new proxy shape
+                    // and the root layer is initially created.
+                    if (rootLayer->IsAnonymous()) {
+                        _anonymousRootLayer = rootLayer;
+                    }
+                }
 
                 if (nullptr == rootLayer) {
                     // Create an empty in-memory root layer so that a new stage in memory

test/lib/mayaUsd/nodes/ProxyShapeBaseTest/CubeModel.usda

@@ -24,3 +24,4 @@ def Xform "CubeModel" (
         }
     }
 }
+

test/lib/mayaUsd/nodes/testLayerManagerSerialization.py

@@ -56,6 +56,10 @@ def setupEmptyScene(self):
         cmds.file(rename=self._tempMayaFile)
 
     def copyTestFilesAndMakeEdits(self):
+        '''
+        Copy an existing Maya scene that contains a stage and a few layer,
+        creates a few USD prim in the root, session and 1_1 layers.
+        '''
         self._currentTestDir = tempfile.mkdtemp(prefix='LayerManagerTest')
         fromDirectory = os.path.join(
             self._inputPath, 'LayerManagerSerializationTest')
@@ -79,13 +83,20 @@ def copyTestFilesAndMakeEdits(self):
         stage = mayaUsd.ufe.getStage(
             "|SerializationTest|SerializationTestShape")
         stack = stage.GetLayerStack()
+        # Note: layers are:
+        #            0: session
+        #            1: root
+        #            2: 1
+        #            3: 1_1
+        #            4: 2
+        #            5: 2_1
         self.assertEqual(6, len(stack))
 
         stage.SetEditTarget(stage.GetRootLayer())
         newPrimPath = "/ChangeInRoot"
         stage.DefinePrim(newPrimPath, "xform")
 
-        stage.SetEditTarget(stack[2])
+        stage.SetEditTarget(stack[3])
         newPrimPath = "/ChangeInLayer_1_1"
         stage.DefinePrim(newPrimPath, "xform")
 
@@ -111,6 +122,10 @@ def copyTestFilesAndMakeEdits(self):
         return stage
 
     def confirmEditsSavedStatus(self, fileBackedSavedStatus, sessionSavedStatus):
+        '''
+        Clears the Maya scene, creates a new USD stage with the root layer
+        and verify various prim existence based on given flags.
+        '''
         cmds.file(new=True, force=True)
 
         proxyNode, stage = createProxyFromFile(self._rootUsdFile)

test/lib/mayaUsd/nodes/testProxyShapeBase.py

@@ -396,6 +396,46 @@ def testShareStagePreserveTCPS(self):
         self.assertEqual(stage.GetTimeCodesPerSecond(), tcps)
         self.assertEqual(stage.GetRootLayer().timeCodesPerSecond, tcps)
 
+    def _getStage(self):
+        '''
+        Helper to get the stage, Needed since the stage instance will change
+        after saving.
+        '''
+        proxyShapes = cmds.ls(type="mayaUsdProxyShapeBase", long=True)
+        self.assertGreater(len(proxyShapes), 0)
+        proxyShapePath = proxyShapes[0]
+        return mayaUsd.lib.GetPrim(proxyShapePath).GetStage(), proxyShapePath
+
+    def _defineDummyPrim(self, stage = None, target = None):
+        '''
+        Define a prim named "dummy". Can be create in an edit target if given one.
+        '''
+        if stage is None:
+            stage, _ = self._getStage()
+        if target is not None:
+            stage.SetEditTarget(target)
+        return stage.DefinePrim("/dummy", "xform")
+
+    def _verifyPrim(self, isActive = True):
+        '''
+        Verify that the prim named "dummy" exists and its active state.
+        '''
+        stage, _ = self._getStage()
+        prim = stage.GetPrimAtPath("/dummy")
+        self.assertTrue(prim)
+        self.assertEqual(prim.IsActive(), isActive)
+
+    def _verifySubLayer(self, expectedCount = 3):
+        '''
+        Verify that the stage still contains a sub-layer under the root.
+        Can pass the expected count if the setup is modified, for example
+        when the stage is not shared, an extra layer added.
+        '''
+        stage, _ = self._getStage()
+        stack = stage.GetLayerStack()
+        # Layer stack: session, root, sub-layer
+        self.assertEqual(expectedCount, len(stack))
+
     def testShareStagePreserveSession(self):
         '''
         Verify share/unshare stage preserves the data in the session layer
@@ -406,37 +446,23 @@ def testShareStagePreserveSession(self):
         # Open usdCylinder.ma scene in testSamples
         mayaUtils.openCylinderScene()
 
-        # get the stage
-        def getStage():
-            proxyShapes = cmds.ls(type="mayaUsdProxyShapeBase", long=True)
-            self.assertGreater(len(proxyShapes), 0)
-            proxyShapePath = proxyShapes[0]
-            return mayaUsd.lib.GetPrim(proxyShapePath).GetStage(), proxyShapePath
-
         # check that the stage is shared and the root is the right one
-        stage, proxyShapePath = getStage()
+        stage, proxyShapePath = self._getStage()
         self.assertTrue(cmds.getAttr('{}.{}'.format(proxyShapePath,"shareStage")))
 
         # create a prim in the session layer.
-        stage.SetEditTarget(stage.GetSessionLayer())
-        stage.DefinePrim("/dummy", "xform")
-
-        # verify that the prim exists.
-        def verifyPrim():
-            stage, _ = getStage()
-            self.assertTrue(stage.GetPrimAtPath("/dummy"))
-
-        verifyPrim()
+        self._defineDummyPrim(stage, stage.GetSessionLayer())
+        self._verifyPrim()
 
         # unshare the stage and verify the prim in the session layer still exists.
         cmds.setAttr('{}.{}'.format(proxyShapePath,"shareStage"), False)
 
-        verifyPrim()
+        self._verifyPrim()
 
         # re-share the stage and verify the prim in the session layer still exists.
         cmds.setAttr('{}.{}'.format(proxyShapePath,"shareStage"), True)
 
-        verifyPrim()
+        self._verifyPrim()
 
     def _saveStagePreserveLayerHelper(self, targetRoot, saveInMaya):
         '''
@@ -451,34 +477,23 @@ def _saveStagePreserveLayerHelper(self, targetRoot, saveInMaya):
         cmds.file(new=True, force=True)
         mayaUtils.createProxyAndStage()
 
-        # Helper to get the stage, Needed since the stage instance will change
-        # after saving.
-        def getStage():
-            proxyShapes = cmds.ls(type="mayaUsdProxyShapeBase", long=True)
-            self.assertGreater(len(proxyShapes), 0)
-            proxyShapePath = proxyShapes[0]
-            return mayaUsd.lib.GetPrim(proxyShapePath).GetStage(), proxyShapePath
+        stage, proxyShapePath = self._getStage()
 
-        stage, proxyShapePath = getStage()
+        # Create an anonymous sub-layer.
+        subLayer = Sdf.Layer.CreateAnonymous("middleLayer")
+        stage.GetRootLayer().subLayerPaths  = [subLayer.identifier]
 
         # Create a prim in the root layer.
         stage.SetEditTarget(stage.GetRootLayer())
         stage.DefinePrim("/dummy", "xform")
 
         # Make the prim inactive in the desired target layer.
         target = stage.GetRootLayer() if targetRoot else stage.GetSessionLayer()
-        stage.SetEditTarget(target)
-        prim = stage.GetPrimAtPath("/dummy")
+        prim = self._defineDummyPrim(stage, target)
         prim.SetActive(False)
 
         # verify that the prim exists but is inactive.
-        def verifyPrim():
-            stage, _ = getStage()
-            prim = stage.GetPrimAtPath("/dummy")
-            self.assertIsNotNone(prim)
-            self.assertFalse(prim.IsActive())
-
-        verifyPrim()
+        self._verifyPrim(False)
 
         # Temp file names for Maya scene and USD file.
         with testUtils.TemporaryDirectory(prefix='ProxyShapeBase', ignore_errors=True) as testDir:
@@ -496,8 +511,24 @@ def verifyPrim():
             cmds.file(save=True, force=True, type='mayaAscii')
 
             # Verify that the prim is still inactive in the target layer.
+            self._verifyPrim(False)
+            self._verifySubLayer()
+
+            # Reload the file and verify again.
+            cmds.file(new=True, force=True)
+            cmds.file(tempMayaFile, force=True, open=True)
 
-            verifyPrim()
+            self._verifyPrim(False)
+            self._verifySubLayer()
+
+            # Change shared status and verify again. Changing the shared flag recomputes
+            # the stage and its layer, which is what we really want to test here. So we
+            # change an input attribute that we know will recompute the layers.
+            cmds.setAttr('{}.{}'.format(proxyShapePath,"shareStage"), False)
+
+            # Verify that the prim is still inactive in the target layer.
+            self._verifyPrim(False)
+            self._verifySubLayer(4)
 
             cmds.file(new=True, force=True)
 
@@ -537,31 +568,19 @@ def testUnsavedStagePreserveRootLayerWhenUpdated(self):
         cmds.file(new=True, force=True)
         mayaUtils.createProxyAndStage()
 
-        # Helper to get the stage,
-        def getStage():
-            proxyShapes = cmds.ls(type="mayaUsdProxyShapeBase", long=True)
-            self.assertGreater(len(proxyShapes), 0)
-            proxyShapePath = proxyShapes[0]
-            return mayaUsd.lib.GetPrim(proxyShapePath).GetStage(), proxyShapePath
-
         # create a prim in the root layer.
-        stage, proxyShapePath = getStage()
-        stage.SetEditTarget(stage.GetRootLayer())
-        stage.DefinePrim("/dummy", "xform")
+        self._defineDummyPrim()
 
         # verify that the prim exists.
-        def verifyPrim():
-            stage, _ = getStage()
-            self.assertTrue(stage.GetPrimAtPath("/dummy"))
-
-        verifyPrim()
+        self._verifyPrim()
 
         # Set an attribute on the proxy shape. Here we set the loadPayloads.
         # It was already set, this only triggers a Maya node recompute.
+        _, proxyShapePath = self._getStage()
         cmds.setAttr('{}.{}'.format(proxyShapePath,"loadPayloads"), True)
 
         # Verify that we did not lose the data on the root layer.
-        verifyPrim()
+        self._verifyPrim()
 
     def testSettingStageViaIdPreservedWhenSaved(self):
         '''