EMSUSD-2803 fix import of USD with an alembic reference

- Changed all calls to USD in  `meshReadUtils.cpp` to pass `UsdTimeCode::EarliestTime()`.
- Added an import unit test that failed without the fix and now passes.

Author: pierrebai-adsk

lib/mayaUsd/fileio/utils/meshReadUtils.cpp

@@ -238,7 +238,7 @@ MIntArray getMayaFaceVertexAssignmentIds(
 bool isPrimitiveLeftHanded(const UsdGeomMesh& mesh)
 {
     TfToken orientation;
-    if (!mesh.GetOrientationAttr().Get(&orientation)) {
+    if (!mesh.GetOrientationAttr().Get(&orientation, UsdTimeCode::EarliestTime())) {
         return false;
     }
 
@@ -255,7 +255,7 @@ bool assignUVSetPrimvarToMesh(
     const TfToken& primvarName = primvar.GetPrimvarName();
 
     VtVec2fArray uvValues;
-    if (!primvar.Get(&uvValues) || uvValues.empty()) {
+    if (!primvar.Get(&uvValues, UsdTimeCode::EarliestTime()) || uvValues.empty()) {
         TF_WARN(
             "Could not read UV values from primvar '%s' on mesh: %s",
             primvarName.GetText(),
@@ -329,7 +329,7 @@ bool assignUVSetPrimvarToMesh(
     }
 
     VtIntArray assignmentIndices;
-    if (primvar.GetIndices(&assignmentIndices)) {
+    if (primvar.GetIndices(&assignmentIndices, UsdTimeCode::EarliestTime())) {
         if (unauthoredValuesIndex >= 0) {
             // Since the unauthored value was removed above, we need to fix up
             // the assignment indices to replace any index equal to the
@@ -419,23 +419,23 @@ bool assignColorSetPrimvarToMesh(
 
     if (typeName == SdfValueTypeNames->FloatArray) {
         colorRep = MFnMesh::kAlpha;
-        if (!primvar.Get(&alphaArray) || alphaArray.empty()) {
+        if (!primvar.Get(&alphaArray, UsdTimeCode::EarliestTime()) || alphaArray.empty()) {
             status = MS::kFailure;
         } else {
             numValues = alphaArray.size();
         }
     } else if (
         typeName == SdfValueTypeNames->Float3Array || typeName == SdfValueTypeNames->Color3fArray) {
         colorRep = MFnMesh::kRGB;
-        if (!primvar.Get(&rgbArray) || rgbArray.empty()) {
+        if (!primvar.Get(&rgbArray, UsdTimeCode::EarliestTime()) || rgbArray.empty()) {
             status = MS::kFailure;
         } else {
             numValues = rgbArray.size();
         }
     } else if (
         typeName == SdfValueTypeNames->Float4Array || typeName == SdfValueTypeNames->Color4fArray) {
         colorRep = MFnMesh::kRGBA;
-        if (!primvar.Get(&rgbaArray) || rgbaArray.empty()) {
+        if (!primvar.Get(&rgbaArray, UsdTimeCode::EarliestTime()) || rgbaArray.empty()) {
             status = MS::kFailure;
         } else {
             numValues = rgbaArray.size();
@@ -460,7 +460,7 @@ bool assignColorSetPrimvarToMesh(
 
     VtIntArray assignmentIndices;
     int        unauthoredValuesIndex = -1;
-    if (primvar.GetIndices(&assignmentIndices)) {
+    if (primvar.GetIndices(&assignmentIndices, UsdTimeCode::EarliestTime())) {
         // The primvar IS indexed, so the indices array is what determines the
         // number of color values.
         numValues = assignmentIndices.size();
@@ -613,7 +613,7 @@ bool assignConstantPrimvarToMesh(const UsdGeomPrimvar& primvar, MFnMesh& meshFn)
     }
 
     VtValue primvarData;
-    primvar.Get(&primvarData);
+    primvar.Get(&primvarData, UsdTimeCode::EarliestTime());
 
     MStatus status { MS::kSuccess };
     MPlug   plug = meshFn.findPlug(
@@ -769,7 +769,7 @@ void UsdMayaMeshReadUtils::assignInvisibleFaces(const UsdGeomMesh& mesh, const M
 
     // Set Holes
     VtIntArray holeIndices;
-    mesh.GetHoleIndicesAttr().Get(&holeIndices); // not animatable
+    mesh.GetHoleIndicesAttr().Get(&holeIndices, UsdTimeCode::EarliestTime()); // not animatable
     if (!holeIndices.empty()) {
         MUintArray mayaHoleIndices;
         mayaHoleIndices.setLength(holeIndices.size());
@@ -813,8 +813,10 @@ MStatus UsdMayaMeshReadUtils::assignSubDivTagsToMesh(
     // Vert Creasing
     VtIntArray   subdCornerIndices;
     VtFloatArray subdCornerSharpnesses;
-    mesh.GetCornerIndicesAttr().Get(&subdCornerIndices);         // not animatable
-    mesh.GetCornerSharpnessesAttr().Get(&subdCornerSharpnesses); // not animatable
+    mesh.GetCornerIndicesAttr().Get(
+        &subdCornerIndices, UsdTimeCode::EarliestTime()); // not animatable
+    mesh.GetCornerSharpnessesAttr().Get(
+        &subdCornerSharpnesses, UsdTimeCode::EarliestTime()); // not animatable
     if (!subdCornerIndices.empty()) {
         if (subdCornerIndices.size() == subdCornerSharpnesses.size()) {
             statusOK.clear();
@@ -875,9 +877,9 @@ MStatus UsdMayaMeshReadUtils::assignSubDivTagsToMesh(
     VtIntArray   subdCreaseLengths;
     VtIntArray   subdCreaseIndices;
     VtFloatArray subdCreaseSharpnesses;
-    mesh.GetCreaseLengthsAttr().Get(&subdCreaseLengths);
-    mesh.GetCreaseIndicesAttr().Get(&subdCreaseIndices);
-    mesh.GetCreaseSharpnessesAttr().Get(&subdCreaseSharpnesses);
+    mesh.GetCreaseLengthsAttr().Get(&subdCreaseLengths, UsdTimeCode::EarliestTime());
+    mesh.GetCreaseIndicesAttr().Get(&subdCreaseIndices, UsdTimeCode::EarliestTime());
+    mesh.GetCreaseSharpnessesAttr().Get(&subdCreaseSharpnesses, UsdTimeCode::EarliestTime());
     if (!subdCreaseLengths.empty()) {
         if (subdCreaseLengths.size() == subdCreaseSharpnesses.size()) {
             MUintArray   mayaCreaseEdgeIds;
@@ -1060,7 +1062,7 @@ MStatus UsdMayaMeshReadUtils::getComponentTags(
         // Get the indices out of the subset
         VtIntArray   faceIndices;
         UsdAttribute indicesAttribute = ss.GetIndicesAttr();
-        indicesAttribute.Get(&faceIndices);
+        indicesAttribute.Get(&faceIndices, UsdTimeCode::EarliestTime());
 
         MFnSingleIndexedComponent compFn;
         MObject                   faceComp = compFn.create(MFn::kMeshPolygonComponent, &status);
@@ -1079,7 +1081,7 @@ MStatus UsdMayaMeshReadUtils::getComponentTags(
         JsObject subsetRoundtripData;
 
         TfToken familyName;
-        ss.GetFamilyNameAttr().Get(&familyName);
+        ss.GetFamilyNameAttr().Get(&familyName, UsdTimeCode::EarliestTime());
         if (familyName != UsdMayaGeomSubsetTokens->ComponentTagFamilyName) {
             subsetRoundtripData[ss.GetFamilyNameAttr().GetBaseName()]
                 = JsValue(familyName.GetString());

test/lib/usd/translators/CMakeLists.txt

@@ -81,6 +81,7 @@ set(TEST_SCRIPT_FILES
     testUsdImportInstances.py
     testUsdImportLight.py
     testUsdImportMayaReference.py
+    testUsdImportAlembicReference.py
     testUsdImportMesh.py
     testUsdImportPointCache.py
     testUsdImportPreviewSurface.py

test/lib/usd/translators/UsdImportAlembicReferenceTest/cone.abc

@@ -0,0 +1,18 @@
+#usda 1.0
+(
+    defaultPrim = "root"
+    metersPerUnit = 0.01
+    upAxis = "Y"
+)
+
+def Xform "root" (
+    prepend apiSchemas = ["GeomModelAPI"]
+)
+{
+    def Mesh "refer" (
+        prepend references = @./cone.abc@
+    )
+    {
+    }
+}
+

test/lib/usd/translators/UsdImportAlembicReferenceTest/referencing-cone.usda

@@ -0,0 +1,60 @@
+#!/usr/bin/env mayapy
+#
+# Copyright 2026 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.
+#
+
+from pxr import UsdGeom
+
+import mayaUsd.lib as mayaUsdLib
+
+from maya import cmds
+from maya import standalone
+
+import os
+import unittest
+
+import fixturesUtils
+
+class testUsdImportAlembicReference(unittest.TestCase):
+
+    @classmethod
+    def setUpClass(cls):
+        inputPath = fixturesUtils.readOnlySetUpClass(__file__)
+
+        usdFile = os.path.join(inputPath, "UsdImportAlembicReferenceTest", "referencing-cone.usda")
+        cmds.usdImport(file=usdFile, shadingMode=[['none', 'default'], ])
+
+    @classmethod
+    def tearDownClass(cls):
+        standalone.uninitialize()
+
+    def verifyUVSet(self, mesh):
+        self.assertTrue(cmds.objExists(mesh))
+        self.assertEqual(cmds.getAttr(mesh + ".uvSet", size=True), 1)
+        self.assertEqual(cmds.getAttr(mesh + ".uvSet[0].uvSetName"), "st")
+        self.assertEqual(cmds.getAttr(mesh + ".uvSet[0].uvSetPoints", size=True), 42)
+        self.assertAlmostEqual(cmds.getAttr(mesh + ".uvSet[0].uvSetPoints[0]")[0][0], 0.73776429, places=6)
+        self.assertAlmostEqual(cmds.getAttr(mesh + ".uvSet[0].uvSetPoints[0]")[0][1], 0.1727457, places=6)
+        self.assertAlmostEqual(cmds.getAttr(mesh + ".uvSet[0].uvSetPoints[1]")[0][0], 0.70225441, places=6)
+        self.assertAlmostEqual(cmds.getAttr(mesh + ".uvSet[0].uvSetPoints[1]")[0][1], 0.103053599, places=6)
+        self.assertAlmostEqual(cmds.getAttr(mesh + ".uvSet[0].uvSetPoints[41]")[0][0], 0.5, places=6)
+        self.assertAlmostEqual(cmds.getAttr(mesh + ".uvSet[0].uvSetPoints[41]")[0][1], 1.0, places=6)
+
+    def testImportPoly(self):
+        self.verifyUVSet('refer')
+
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2)