Made ImGuiMenu plugin more flexible for customization.

Now viewer menu can be overriden with lambda function (for simple
override), or virtual methods (for more complex situations).


Former-commit-id: 37d585ef87f98bd1c2b47dcdfa8b8bd7e7b83158

include/igl/opengl/glfw/imgui/ImGuiMenu.cpp

@@ -140,7 +140,7 @@ IGL_INLINE bool ImGuiMenu::key_up(int key, int modifiers)
 IGL_INLINE void ImGuiMenu::draw_menu()
 {
   // Text labels
-  draw_labels_menu();
+  draw_labels_window();
 
   // Viewer settings
   float menu_width = 180.f * menu_scaling();
@@ -154,12 +154,14 @@ IGL_INLINE void ImGuiMenu::draw_menu()
       | ImGuiWindowFlags_AlwaysAutoResize
   );
   ImGui::PushItemWidth(ImGui::GetWindowWidth() * 0.4f);
-  draw_viewer_menu();
+  if (draw_viewer_menu_func) { draw_viewer_menu_func(); }
+  else { draw_viewer_menu(); }
   ImGui::PopItemWidth();
   ImGui::End();
 
-  // Other menus
-  draw_other_menu();
+  // Other windows
+  if (draw_custom_window_func) { draw_custom_window_func(); }
+  else { draw_custom_window(); }
 }
 
 IGL_INLINE void ImGuiMenu::draw_viewer_menu()
@@ -276,7 +278,7 @@ IGL_INLINE void ImGuiMenu::draw_viewer_menu()
   }
 }
 
-IGL_INLINE void ImGuiMenu::draw_labels_menu()
+IGL_INLINE void ImGuiMenu::draw_labels_window()
 {
   // Text labels
   ImGui::SetNextWindowPos(ImVec2(0,0), ImGuiSetCond_Always);

include/igl/opengl/glfw/imgui/ImGuiMenu.h

@@ -73,9 +73,13 @@ public:
 
   IGL_INLINE virtual void draw_viewer_menu();
 
-  IGL_INLINE virtual void draw_other_menu() { }
+  IGL_INLINE virtual void draw_custom_window() { }
 
-  IGL_INLINE void draw_labels_menu();
+  // Easy-to-customize callbacks
+  std::function<void(void)> draw_viewer_menu_func;
+  std::function<void(void)> draw_custom_window_func;
+
+  IGL_INLINE void draw_labels_window();
 
   IGL_INLINE void draw_labels(const igl::opengl::ViewerData &data);
 

tutorial/106_ViewerMenu/main.cpp

@@ -6,7 +6,7 @@
 #include <iostream>
 #include "tutorial_shared_path.h"
 
-class MyMenu : public igl::opengl::glfw::imgui::ImGuiMenu
+class CustomMenu : public igl::opengl::glfw::imgui::ImGuiMenu
 {
   float floatVariable = 0.1f; // Shared between two menus
 
@@ -60,7 +60,7 @@ class MyMenu : public igl::opengl::glfw::imgui::ImGuiMenu
     }
   }
 
-  virtual void draw_other_menu() override
+  virtual void draw_custom_window() override
   {
     // Define next window position + size
     ImGui::SetNextWindowPos(ImVec2(180.f * menu_scaling(), 10), ImGuiSetCond_FirstUseEver);
@@ -95,8 +95,7 @@ int main(int argc, char *argv[])
   igl::opengl::glfw::Viewer viewer;
 
   // Attach a custom menu
-  MyMenu menu;
-  // viewer.core.is_animating = true;
+  CustomMenu menu;
   viewer.plugins.push_back(&menu);
 
   // Plot the mesh

tutorial/107_MultipleMeshes/main.cpp

@@ -25,21 +25,6 @@ void update_colors(igl::opengl::glfw::Viewer &viewer)
   last_colored_index = viewer.selected_data_index;
 }
 
-// Menu for selecting a mesh
-class MyMenu : public igl::opengl::glfw::imgui::ImGuiMenu
-{
-  virtual void draw_viewer_menu() override
-  {
-    if (ImGui::Combo("Selected Mesh", (int *) &viewer->selected_data_index,
-          [&](int i) { return viewer->data_list[i].attr<MeshData>().name.c_str(); },
-          viewer->data_list.size())
-      || last_colored_index != viewer->selected_data_index)
-    {
-      update_colors(*viewer);
-    }
-  }
-};
-
 int main(int argc, char * argv[])
 {
   igl::opengl::glfw::Viewer viewer;
@@ -52,9 +37,21 @@ int main(int argc, char * argv[])
   }
 
   // Attach a custom menu
-  MyMenu menu;
+  igl::opengl::glfw::imgui::ImGuiMenu menu;
   viewer.plugins.push_back(&menu);
 
+  // Customize default menu
+  menu.draw_viewer_menu_func = [&]()
+  {
+    if (ImGui::Combo("Selected Mesh", (int *) &viewer.selected_data_index,
+          [&](int i) { return viewer.data_list[i].attr<MeshData>().name.c_str(); },
+          viewer.data_list.size())
+      || last_colored_index != viewer.selected_data_index)
+    {
+      update_colors(viewer);
+    }
+  };
+
   // Color each mesh differently
   update_colors(viewer);