HYDRA-764 : Add prim instancing unit test (#33)

* HYDRA-764 : Create minimalized version of ALab workbench scene

* HYDRA-764 : Further simplify the USD scene

* HYDRA-764 : Convert geometry usdc file to usda and remove some meshes

* HYDRA-764 : Replace workbench with simple cube

* HYDRA-764 : Have just the root Xform reference the cube in the scene file

* HYDRA-674 : Rename Xform and mesh in cube.usda

* HYDRA-764 : First working test

* HYDRA-764 : Extract USD stage load from file logic into utils

* HYDRA-764 : Add extra checks in scene hierarchy

* HYDRA-764 : Comment scene file

* HYDRA-764 : Cleanup unused imports and includes

* HYDRA-764 : Rename root prim

* HYDRA-764 : Move usdUtils import inside a function called after MayaUSD is loaded

* HYDRA-764 : Remove incorrect comment in usda scene file

* HYDRA-764 : Rename scene file

test/lib/mayaUsd/render/mayaToHydra/CMakeLists.txt

@@ -25,6 +25,7 @@ set(TEST_SCRIPT_FILES
     cpp/testFlowViewportAPIAddPrims.py
     cpp/testUsdStageLayerMuting.py
     cpp/testFlowViewportAPIFilterPrims.py
+    cpp/testPrimInstancing.py
 )
 
 # Test use of mesh adapter code for mesh support, using environment variable.

test/lib/mayaUsd/render/mayaToHydra/cpp/CMakeLists.txt

@@ -26,6 +26,7 @@ target_sources(${TARGET_NAME}
         testUsdStageLayerMuting.cpp
         testMeshAdapterTransform.cpp
         testFlowViewportAPIFilterPrims.cpp
+        testPrimInstancing.cpp
 )
 
 # -----------------------------------------------------------------------------

test/lib/mayaUsd/render/mayaToHydra/cpp/testPrimInstancing.cpp

@@ -0,0 +1,68 @@
+// Copyright 2023 Autodesk
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include "testUtils.h"
+
+#include <pxr/imaging/hd/tokens.h>
+
+#include <gtest/gtest.h>
+
+PXR_NAMESPACE_USING_DIRECTIVE
+
+namespace {
+FindPrimPredicate findInstanceableCubePredicate = PrimNamePredicate("instanceableCube");
+HdDataSourceLocator instancerLocator = HdDataSourceLocator(TfToken("instance"), TfToken("instancer"));
+} // namespace
+
+TEST(PrimInstancing, testUsdPrimInstancing)
+{
+    // Get the terminal scene index
+    const auto& sceneIndices = GetTerminalSceneIndices();
+    ASSERT_GT(sceneIndices.size(), 0u);
+    SceneIndexInspector inspector(sceneIndices.front());
+
+    // Find the instanceable cube prim
+    PrimEntriesVector instanceableCubePrims = inspector.FindPrims(findInstanceableCubePredicate);
+    ASSERT_EQ(instanceableCubePrims.size(), 1u);
+    HdSceneIndexPrim instanceableCubePrim = instanceableCubePrims.front().prim;
+
+    // Retrieve the instancer data source
+    auto instancerDataSource = HdTypedSampledDataSource<SdfPath>::Cast(
+        HdContainerDataSource::Get(instanceableCubePrim.dataSource, instancerLocator));
+    ASSERT_TRUE(instancerDataSource);
+
+    // Ensure the instancer prim exists and is populated
+    SdfPath instancerPath = instancerDataSource->GetTypedValue(0);
+    auto findInstancerPredicate
+        = [instancerPath](const HdSceneIndexBasePtr& sceneIndex, const SdfPath& primPath) -> bool {
+        return primPath == instancerPath;
+    };
+    PrimEntriesVector instancerPrims = inspector.FindPrims(findInstancerPredicate);
+    ASSERT_EQ(instancerPrims.size(), 1u);
+    HdSceneIndexPrim instancerPrim = instancerPrims.front().prim;
+    ASSERT_EQ(instancerPrim.primType, HdPrimTypeTokens->instancer);
+    ASSERT_NE(instancerPrim.dataSource, nullptr);
+
+    // Ensure the reference cube prim exists and is populated
+    auto findCubePredicate
+        = [instancerPath](const HdSceneIndexBasePtr& sceneIndex, const SdfPath& primPath) -> bool {
+        return primPath.HasPrefix(instancerPath) && primPath.GetName() == "cubeMesh";
+    };
+    PrimEntriesVector cubePrims = inspector.FindPrims(findCubePredicate);
+    ASSERT_EQ(cubePrims.size(), 1u);
+    HdSceneIndexPrim cubePrim = cubePrims.front().prim;
+    ASSERT_EQ(cubePrim.primType, HdPrimTypeTokens->mesh);
+    ASSERT_NE(cubePrim.dataSource, nullptr);
+}

test/lib/mayaUsd/render/mayaToHydra/cpp/testPrimInstancing.py

@@ -0,0 +1,42 @@
+# Copyright 2023 Autodesk
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+import maya.cmds as cmds
+
+import fixturesUtils
+import mtohUtils
+import unittest
+
+import testUtils
+from testUtils import PluginLoaded
+
+class TestPrimInstancing(mtohUtils.MayaHydraBaseTestCase):
+    # MayaHydraBaseTestCase.setUpClass requirement.
+    _file = __file__
+
+    def loadUsdScene(self):
+        import usdUtils
+        usdScenePath = testUtils.getTestScene('testPrimInstancing', 'instanceableCube.usda')
+        usdUtils.createStageFromFile(usdScenePath)
+        self.setHdStormRenderer()
+        cmds.refresh()
+
+    @unittest.skipUnless(mtohUtils.checkForMayaUsdPlugin(), "Requires Maya USD Plugin.")
+    def test_UsdPrimInstancing(self):
+        self.loadUsdScene()
+        with PluginLoaded('mayaHydraCppTests'):
+            cmds.mayaHydraCppTest(f="PrimInstancing.testUsdPrimInstancing")
+
+if __name__ == '__main__':
+    fixturesUtils.runTests(globals())

test/testSamples/testPrimInstancing/cube.usda

@@ -0,0 +1,14 @@
+#usda 1.0
+(
+    defaultPrim = "cube"
+)
+
+def Xform "cube"
+{
+    def Mesh "cubeMesh"
+    {
+        int[] faceVertexCounts = [4, 4, 4, 4, 4, 4]
+        int[] faceVertexIndices = [0, 1, 3, 2, 2, 3, 5, 4, 4, 5, 7, 6, 6, 7, 1, 0, 1, 7, 5, 3, 6, 0, 2, 4]
+        point3f[] points = [(-0.5, -0.5, 0.5), (0.5, -0.5, 0.5), (-0.5, 0.5, 0.5), (0.5, 0.5, 0.5), (-0.5, 0.5, -0.5), (0.5, 0.5, -0.5), (-0.5, -0.5, -0.5), (0.5, -0.5, -0.5)]
+    }
+}

test/testSamples/testPrimInstancing/instanceableCube.usda

@@ -0,0 +1,11 @@
+#usda 1.0
+(
+    defaultPrim = "instanceableCube"
+)
+
+def Xform "instanceableCube" (
+    instanceable = true
+    prepend references = @cube.usda@
+)
+{
+}

test/testUtils/usdUtils.py

@@ -20,6 +20,8 @@
     Helper functions regarding USD that will be used throughout the test.
 """
 
+import maya.mel as mel
+
 import mayaUsd.ufe
 import mayaUsd.lib
 import mayaUsd_createStageWithNewLayer
@@ -31,6 +33,20 @@
 
 usdSeparator = '/'
 
+def createStageFromFile(filePath: str):
+    """
+        Creates a USD stage from a given path to a USD file.
+        Args:
+            filePath (str): The file path to the USD file to load.
+        Returns :
+            A string representing the UFE path to the stage's proxy shape node
+    """
+    # Source the corresponding mel file, otherwise the procedure isn't available
+    mel.eval('source \"mayaUsd_createStageFromFile.mel\"')
+    loadStageCmd = f'mayaUsd_createStageFromFilePath(\"{filePath}\")'
+    # Replace backslashes with forward slashes to avoid them being interpreted
+    loadStageCmd = loadStageCmd.replace('\\', '/')
+    return mel.eval(loadStageCmd)
 
 def createUfePathSegment(usdPath):
     """