use normals as origin point

headers/tetrahedronGenerator.hpp

@@ -52,6 +52,7 @@ inline void createTetrahedronModel(std::string plyFile) {
   dist *= 0.2f;
 
   int i = 1;
+  int vn_i = 1;
   for (pcl::PointXYZRGB &pt : cloud->points) {
     std::vector<pcl::PointXYZ> vertex =
         calculateTetrahedronVertices(dist, pt.x, pt.y, pt.z);
@@ -63,12 +64,22 @@ inline void createTetrahedronModel(std::string plyFile) {
            << std::endl;
     }
 
+    // write the original point coordinate as the vertex normal
+    fout << "vn " << pt.x << " " << pt.y << " " << pt.z << std::endl;
+
     // write the faces
-    fout << "f " << i << " " << i + 1 << " " << i + 2 << std::endl;
-    fout << "f " << i << " " << i + 2 << " " << i + 3 << std::endl;
-    fout << "f " << i << " " << i + 3 << " " << i + 1 << std::endl;
-    fout << "f " << i + 1 << " " << i + 3 << " " << i + 2 << std::endl;
+    std::string vn = "//" + std::to_string(vn_i);
+    fout << "f " << i << vn << " " << i + 1 << vn << " " << i + 2 << vn
+         << std::endl;
+    fout << "f " << i << vn << " " << i + 2 << vn << " " << i + 3 << vn
+         << std::endl;
+    fout << "f " << i << vn << " " << i + 3 << vn << " " << i + 1 << vn
+         << std::endl;
+    fout << "f " << i + 1 << vn << " " << i + 3 << vn << " " << i + 2 << vn
+         << std::endl;
+
     i += 4;
+    vn_i++;
   }
 
   fout.close();