Fixes a bug in writePLY introduced in dfda6de04ee733a7b00b1edc57051d1fee78b219 (#1867)

Addes a test to make sure it works as expected

include/igl/writePLY.cpp

@@ -147,7 +147,7 @@ bool writePLY(
         _ed.resize(ED.size());
         Eigen::Map<Eigen::Matrix<EDScalar, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor > >( &_ed[0], ED.rows(), ED.cols() ) = ED;
 
-        file.add_properties_to_element("face", FDheader,
+        file.add_properties_to_element("edge", EDheader,
             tynyply_type<EDScalar>(), ED.rows(), reinterpret_cast<uint8_t*>( &_ed[0] ), tinyply::Type::INVALID, 0);
     }
 

tests/include/igl/writePLY.cpp

@@ -1,6 +1,7 @@
 #include <test_common.h>
 #include <igl/readPLY.h>
 #include <igl/writePLY.h>
+#include <igl/edges.h>
 #include <fstream>
 #include <string>
 #include <vector>
@@ -31,12 +32,37 @@ TEST_CASE("writePLY: bunny.ply", "[igl]")
     Eigen::VectorXd face_data(F1.rows());
     for(size_t i=0;i<F1.rows();++i)
         face_data(i)=(double)i;
-    Eigen::MatrixXd FD2(F1.rows(),FD1.cols()+1);
+
+
+
     // there is no face data in the input file
+    Eigen::MatrixXd FD2(F1.rows(),FD1.cols()+1);
     FD2<<face_data;
 
+    //input file have no edge data
+    REQUIRE (E1.rows() == 0);
+    REQUIRE (E1.cols() == 0);
+    REQUIRE (ED1.rows() == 0);
+    REQUIRE (Eheader1.empty());    
+
+    Eigen::MatrixXi E2;
+    std::vector<std::string> Eheader2;
+
+    //generate edges
+    igl::edges(F1,E2);
+
+    //generate edge data
+    Eheader2.push_back("edge_data");
+    Eigen::VectorXd edge_data(E2.rows());
+    for(size_t i=0;i<E2.rows();++i)
+        edge_data(i)=(double)i;
+    
+    // there is no edge data in the input file
+    Eigen::MatrixXd ED2(E2.rows(),1);
+    ED2<<edge_data;
+
     // test that saving preserves all the data, including new data column
-    REQUIRE (igl::writePLY("writePLY_test_bunny.ply", V1, F1, E1, N1, UV1, VD2, Vheader1, FD2,Fheader1, ED1, Eheader1, comments1, igl::FileEncoding::Binary));
+    REQUIRE (igl::writePLY("writePLY_test_bunny.ply", V1, F1, E2, N1, UV1, VD2, Vheader1, FD2,Fheader1, ED2, Eheader2, comments1, igl::FileEncoding::Binary));
 
     Eigen::MatrixXd V,N,UV,VD,FD,ED;
     Eigen::MatrixXi F,E;
@@ -49,9 +75,10 @@ TEST_CASE("writePLY: bunny.ply", "[igl]")
     REQUIRE (V.cols() == 3);
     REQUIRE (F.rows() == 69451);
     REQUIRE (F.cols() == 3);
-    // no edge data
-    REQUIRE (E.rows() == 0);
-    REQUIRE (E.cols() == 0);
+
+    // generated edges
+    REQUIRE (E.rows() == E2.rows());
+    REQUIRE (E.cols() == E2.cols());
 
     // no normals or texture coordinates
     REQUIRE (N.rows() == 0);
@@ -72,7 +99,7 @@ TEST_CASE("writePLY: bunny.ply", "[igl]")
     REQUIRE (Vheader[1] == "intensity" );
     REQUIRE (Vheader[2] == "dummy_data" );
 
-    // Face should have only one column
+    // Face datashould have only one column
     REQUIRE (Fheader.size() == 1);
     REQUIRE (Fheader[0] == "face_data" );
     REQUIRE (FD.rows() == F.rows());
@@ -82,9 +109,16 @@ TEST_CASE("writePLY: bunny.ply", "[igl]")
     for(size_t i=0;i<F.rows();++i)
         REQUIRE (FD(i,0) == (double)i);
 
-    REQUIRE (ED.rows() == 0);
-    REQUIRE (ED.cols() == 0);
-    REQUIRE (Eheader.size() == 0);
+    // Edge data should have only one column
+    REQUIRE (Eheader.size() == 1);
+    REQUIRE (Eheader[0] == "edge_data" );
+    REQUIRE (ED.rows() == E.rows());
+    REQUIRE (ED.cols() == 1);
+
+    // the dummy column contents check
+    for(size_t i=0;i<E.rows();++i)
+        REQUIRE (ED(i,0) == (double)i);
+
 
     // there are comments
     REQUIRE (comments.size() == 2);