Color selected mesh in red.

Former-commit-id: 84be11b1b263d031d3f32d3751f0656f406680ca

tutorial/107_MultipleMeshes/main.cpp

@@ -4,27 +4,24 @@
 #include <string>
 #include <iostream>
 
+// Add custom data to a viewer mesh
+struct MeshData
+{
+  Eigen::RowVector3d color;
+};
+
 int main(int argc, char * argv[])
 {
   igl::opengl::glfw::Viewer viewer;
-  const auto names = 
+  const auto names =
     {"cube.obj","sphere.obj","xcylinder.obj","ycylinder.obj","zcylinder.obj"};
   for(const auto & name : names)
   {
     viewer.load_mesh_from_file(std::string(TUTORIAL_SHARED_PATH) + "/" + name);
+    viewer.data().attr<MeshData>().color = 0.5*Eigen::RowVector3d::Random().array() + 0.5;
   }
 
-  // Set colors of each mesh by selecting its index first
-  viewer.selected_data_index = 0;
-  viewer.data().set_colors(Eigen::RowVector3d(0.8,0.47,0.22));
-  viewer.selected_data_index = 1;
-  viewer.data().set_colors(Eigen::RowVector3d(0.6,0.01,0.11));
-  viewer.selected_data_index = 2;
-  viewer.data().set_colors(Eigen::RowVector3d(0.37,0.06,0.25));
-  viewer.selected_data_index = 3;
-  viewer.data().set_colors(Eigen::RowVector3d(1,1,1));
-
-  viewer.callback_key_down = 
+  viewer.callback_key_down =
     [&](igl::opengl::glfw::Viewer &, unsigned int key, int mod)
   {
     if(key == GLFW_KEY_BACKSPACE)
@@ -35,6 +32,23 @@ int main(int argc, char * argv[])
     return false;
   };
 
+  // Refresh selected mesh colors
+  viewer.callback_pre_draw =
+    [&](igl::opengl::glfw::Viewer &)
+  {
+    static int last_selected = -1;
+    if (last_selected != viewer.selected_data_index)
+    {
+      for (auto &data : viewer.data_list)
+      {
+        data.set_colors(data.attr<MeshData>().color);
+      }
+      viewer.data_list[viewer.selected_data_index].set_colors(Eigen::RowVector3d(0.9,0.1,0.1));
+      last_selected = viewer.selected_data_index;
+    }
+    return false;
+  };
+
   viewer.launch();
   return EXIT_SUCCESS;
 }