Fix Issue #18719: vtkPLYReader Bug For Face Textured PLYs

In some cases vtkPlyReader wrongly re-used vertices with differing coordinates
for some face-textured files with duplicate texture coordinates.
Fix by removing one if-statement. Add test case as well.

IO/PLY/Testing/CMakeLists.txt

@@ -1,5 +1,6 @@
 vtk_module_test_data(
   Data/Armadillo.ply
+  Data/FaceTexturedWithReusedTCoords.ply
   Data/PointCloud.ply
   Data/bunny.ply
   Data/squareTextured.ply

IO/PLY/Testing/Cxx/CMakeLists.txt

@@ -15,4 +15,8 @@ vtk_add_test_cxx(vtkIOPLYCxxTests tests
   TestPLYReaderTextureUVFaces,TestPLYReaderTextureUV.cxx squareTexturedFaces.ply
   two_vtk_logos_stacked.png
 )
+vtk_add_test_cxx(vtkIOPLYCxxTests tests
+  TestPLYReaderFaceTexturedWithReusedTCoord,TestPLYReaderTextureUV.cxx FaceTexturedWithReusedTCoords.ply
+  vtk.png
+)
 vtk_test_cxx_executable(vtkIOPLYCxxTests tests)

IO/PLY/Testing/Data/Baseline/TestPLYReaderFaceTexturedWithReusedTCoord.png.sha512

@@ -0,0 +1 @@
+5e33790e9793fc4403c03e331dbb78d36b81053ff1d2df9b75203fdff5962f47b5b6a760b27698fce5eeaa0c34b2e8d685c4427a0d5a4755b9809abe5934ecef

IO/PLY/vtkPLYReader.cxx

@@ -560,27 +560,25 @@ int vtkPLYReader::RequestData(vtkInformation* vtkNotUsed(request),
                     else
                     {
                       size_t sameTexIndex = 0;
-                      if (pointIds[ti].size() > 1)
+
+                      double first[3];
+                      output->GetPoint(vtkVerts[k], first);
+                      for (; sameTexIndex < pointIds[ti].size(); ++sameTexIndex)
                       {
-                        double first[3];
-                        output->GetPoint(vtkVerts[k], first);
-                        for (; sameTexIndex < pointIds[ti].size(); ++sameTexIndex)
-                        {
-                          double second[3];
-                          output->GetPoint(pointIds[ti][sameTexIndex], second);
-                          if (FuzzyEqual(first, second, this->FaceTextureTolerance))
-                          {
-                            break;
-                          }
-                        }
-                        if (sameTexIndex == pointIds[ti].size())
+                        double second[3];
+                        output->GetPoint(pointIds[ti][sameTexIndex], second);
+                        if (FuzzyEqual(first, second, this->FaceTextureTolerance))
                         {
-                          // newly seen point for this texture coordinate
-                          vtkIdType dp = duplicateCellPoint(output, cell, k);
-                          texCoordsPoints->SetTuple2(dp, newTex[0], newTex[1]);
-                          pointIds[ti].push_back(dp);
+                          break;
                         }
                       }
+                      if (sameTexIndex == pointIds[ti].size())
+                      {
+                        // newly seen point for this texture coordinate
+                        vtkIdType dp = duplicateCellPoint(output, cell, k);
+                        texCoordsPoints->SetTuple2(dp, newTex[0], newTex[1]);
+                        pointIds[ti].push_back(dp);
+                      }
 
                       // texture coordinate already seen before, use the vertex
                       // associated with these texture coordinates

Testing/Data/FaceTexturedWithReusedTCoords.ply.sha512

@@ -0,0 +1 @@
+d6cf1cf267ce056887444ea5325abee7957b283480471d64a0e28f88dbd9d7e8dc7559a65324b213596206b02ae3b8b33287a048a2e31f7252d0e1dc6e6e7b5b