Native instance picking. (#107)

* Native instance picking.

* Fixed gcc 11.2 Linux compilation.

lib/mayaHydra/mayaPlugin/renderOverride.cpp

@@ -393,6 +393,26 @@ class UsdPickHandler : public MtohRenderOverride::PickHandlerBase {
             return {primOrigin.GetFullPath(), -1};
         }
 
+        // If there is a Hydra instancer, distinguish between native instancing
+        // (implicit USD prototype created by USD itself) and point instancing
+        // (explicitly authored USD prototypes).  As per HdxInstancerContext
+        // documentation:
+        // 
+        // [...] "exactly one of instancePrimOrigin or instancerPrimOrigin will
+        // contain data depending on whether the instancing at the current
+        // level was implicit or not, respectively."
+        const auto& instancerContext = primOrigin.instancerContexts.front();
+
+        if (instancerContext.instancePrimOrigin) {
+            // Implicit prototype instancing (i.e. USD native instancing).
+            auto schema = HdPrimOriginSchema(instancerContext.instancePrimOrigin);
+            if (!TF_VERIFY(schema, "Cannot build prim origin schema for USD native instance.")) {
+                return {SdfPath(), -1};
+            }
+            return {schema.GetOriginPath(HdPrimOriginSchemaTokens->scenePath), -1};
+        }
+
+        // Explicit prototype instancing (i.e. USD point instancing).
         std::function<HitPath(const HdxPrimOriginInfo& primOrigin, const HdxPickHit& hit)> pickFn[] = {pickInstancer, pickInstance, pickPrototype};
 
         // Retrieve pick mode from mayaUsd optionVar, to see if we're picking

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

@@ -47,6 +47,7 @@ set(INTERACTIVE_TEST_SCRIPT_FILES
     cpp/testPrimInstancing.py
     cpp/testPicking.py
     cpp/testPointInstancePicking.py
+    cpp/testUsdNativeInstancePicking.py
 )
 
 #Add this test only if the MayaUsd_FOUND (so also MAYAUSDAPI_LIBRARY) has been found during compile time.

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

@@ -36,6 +36,7 @@ target_sources(${TARGET_NAME}
         testPrimInstancing.cpp
         testPicking.cpp
         testPointInstancePicking.cpp
+        testUsdNativeInstancePicking.cpp
 )
 
 # -----------------------------------------------------------------------------

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

@@ -0,0 +1,116 @@
+// Copyright 2024 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 <maya/M3dView.h>
+#include <maya/MPoint.h>
+
+#include <pxr/imaging/hd/selectionSchema.h>
+#include <pxr/imaging/hd/selectionsSchema.h>
+
+#include <ufe/path.h>
+#include <ufe/pathString.h>
+#include <ufe/observableSelection.h>
+#include <ufe/globalSelection.h>
+
+#include <gtest/gtest.h>
+
+PXR_NAMESPACE_USING_DIRECTIVE
+
+using namespace MayaHydra;
+
+TEST(TestUsdNativeInstancePicking, pickInstance)
+{
+    const auto& sceneIndices = GetTerminalSceneIndices();
+    ASSERT_GT(sceneIndices.size(), 0u);
+    auto siRoot = sceneIndices.front();
+
+    auto [argc, argv] = getTestingArgs();
+    ASSERT_EQ(argc, 1);
+    const Ufe::Path selected(Ufe::PathString::path(argv[0]));
+
+    // Maya selection API doesn't understand USD data, which can only be
+    // represented through UFE, so use UFE API to interact with Maya selection.
+    const auto sn = Ufe::GlobalSelection::get();
+    sn->clear();
+
+    // Translate the application path into a scene index path using the
+    // selection scene index.
+    // The Flow Viewport selection scene index is in the scene index tree.
+    const auto snSi = findSelectionSceneIndexInTree(siRoot);
+    ASSERT_TRUE(snSi);
+
+    const auto sceneIndexPath = snSi->SceneIndexPath(selected);
+
+    ASSERT_FALSE(sceneIndexPath.IsEmpty());
+
+    const auto prim = siRoot->GetPrim(sceneIndexPath);
+    ASSERT_TRUE(prim.dataSource);
+
+    // There is no selections data source on the prim.
+    auto dataSourceNames = prim.dataSource->GetNames();
+    ASSERT_EQ(std::find(dataSourceNames.begin(), dataSourceNames.end(), HdSelectionsSchemaTokens->selections), dataSourceNames.end());
+
+    // Selection scene index says the prim is not selected.
+    ASSERT_FALSE(snSi->IsFullySelected(sceneIndexPath));
+
+    //======================================================================
+    // Perform a pick
+    //======================================================================
+
+    M3dView active3dView = M3dView::active3dView();
+
+    const auto primMouseCoords = getPrimMouseCoords(prim, active3dView);
+
+    mouseClick(Qt::MouseButton::LeftButton, active3dView.widget(), primMouseCoords);
+    active3dView.refresh();
+
+    //======================================================================
+    // Test that the pick changed the Maya selection
+    //======================================================================
+
+    // When picking on the boundary of multiple objects, one Hydra pick hit per
+    // object is returned.  Therefore test that the expected selected path is
+    // in the selection.
+    ASSERT_GE(sn->size(), 1u);
+    ASSERT_TRUE(sn->contains(selected));
+
+    //======================================================================
+    // Test that the pick changed the Hydra selection
+    //======================================================================
+
+    // On selection, the prim is given a selections data source.
+    dataSourceNames = prim.dataSource->GetNames();
+    ASSERT_NE(std::find(dataSourceNames.begin(), dataSourceNames.end(), HdSelectionsSchemaTokens->selections), dataSourceNames.end());
+
+    auto snDataSource = prim.dataSource->Get(HdSelectionsSchemaTokens->selections);
+    ASSERT_TRUE(snDataSource);
+    auto selectionsSchema = HdSelectionsSchema::GetFromParent(prim.dataSource);
+    ASSERT_TRUE(selectionsSchema);
+
+    // Only one selection in the selections schema.
+    ASSERT_EQ(selectionsSchema.GetNumElements(), 1u);
+    auto selectionSchema = selectionsSchema.GetElement(0);
+
+    // Prim is fully selected.
+    auto ds = selectionSchema.GetFullySelected();
+    ASSERT_TRUE(ds);
+    ASSERT_TRUE(ds->GetTypedValue(0.0f));
+
+    // Selection scene index says the prim is selected.
+    ASSERT_TRUE(snSi->IsFullySelected(sceneIndexPath));
+    ASSERT_TRUE(snSi->HasFullySelectedAncestorInclusive(sceneIndexPath));
+}

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

@@ -0,0 +1,49 @@
+# Copyright 2024 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 usdUtils
+
+import testUtils
+from testUtils import PluginLoaded
+
+class TestUsdNativeInstancePicking(mtohUtils.MtohTestCase):
+    # MayaHydraBaseTestCase.setUpClass requirement.
+    _file = __file__
+
+    PICK_PATH = "|instancedCubeHierarchies|instancedCubeHierarchiesShape,/cubeHierarchies"
+
+    def loadUsdScene(self):
+        usdScenePath = testUtils.getTestScene('testUsdNativeInstances', 'instancedCubeHierarchies.usda')
+        usdUtils.createStageFromFile(usdScenePath)
+
+    def setUp(self):
+        super(TestUsdNativeInstancePicking, self).setUp()
+        self.loadUsdScene()
+        cmds.refresh()
+
+    @unittest.skipUnless(mtohUtils.checkForMayaUsdPlugin(), "Requires Maya USD Plugin.")
+    def test_NativeInstances(self):
+        with PluginLoaded('mayaHydraCppTests'):
+            instances = ["/cubes_1", "/cubes_2"]
+            for instance in instances:
+                cmds.mayaHydraCppTest(
+                    self.PICK_PATH + instance,
+                    f="TestUsdNativeInstancePicking.pickInstance")
+
+if __name__ == '__main__':
+    fixturesUtils.runTests(globals())

test/testSamples/testUsdNativeInstances/cubesHierarchy.usda

@@ -0,0 +1,33 @@
+#usda 1.0
+(
+    defaultPrim = "parent"
+    metersPerUnit = 0.01
+    upAxis = "Y"
+)
+
+def Xform "parent" (
+    kind = "component"
+)
+{
+    def Mesh "topCube"
+    {
+        uniform bool doubleSided = 1
+        float3[] extent = [(-0.25, -0.25, -0.25), (0.25, 0.25, 0.25)]
+        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 = [(-0.25, -0.25, 0.25), (0.25, -0.25, 0.25), (-0.25, 0.25, 0.25), (0.25, 0.25, 0.25), (-0.25, 0.25, -0.25), (0.25, 0.25, -0.25), (-0.25, -0.25, -0.25), (0.25, -0.25, -0.25)]
+        double3 xformOp:translate = (0, 1.25, 0)
+        uniform token[] xformOpOrder = ["xformOp:translate"]
+    }
+
+    def Mesh "baseCube"
+    {
+        uniform bool doubleSided = 1
+        float3[] extent = [(-0.5, -0.5, -0.5), (0.5, 0.5, 0.5)]
+        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)]
+        double3 xformOp:translate = (0, 0.5, 0)
+        uniform token[] xformOpOrder = ["xformOp:translate"]
+    }
+}

test/testSamples/testUsdNativeInstances/instancedCubeHierarchies.usda

@@ -0,0 +1,22 @@
+#usda 1.0
+
+def "cubeHierarchies"
+{
+    def Xform "cubes_1" (
+        instanceable = true
+        references = @./cubesHierarchy.usda@
+    )
+    {
+        double3 xformOp:translate = (-1.0, 0, 0)
+        uniform token[] xformOpOrder = ["xformOp:translate"]
+    }
+
+    def Xform "cubes_2" (
+        instanceable = true
+        references = @./cubesHierarchy.usda@
+    )
+    {
+        double3 xformOp:translate = (1.0, 0, 0)
+        uniform token[] xformOpOrder = ["xformOp:translate"]
+    }
+}