text: // This file is part of libigl, a simple c++ geometry processing library.
  //
  // Copyright (C) 2014 Daniele Panozzo <daniele.panozzo@gmail.com>
  //
  // This Source Code Form is subject to the terms of the Mozilla Public License
  // v. 2.0. If a copy of the MPL was not distributed with this file, You can
  // obtain one at http://mozilla.org/MPL/2.0/.
  #ifndef IGL_OPENGL_GLFW_VIEWER_H
  #define IGL_OPENGL_GLFW_VIEWER_H
  
  #ifndef IGL_OPENGL_4
  #define IGL_OPENGL_4
  #endif
  
  #include "../../igl_inline.h"
  #include "../MeshGL.h"
  #include "../ViewerCore.h"
  #include "../ViewerData.h"
  #include "ViewerPlugin.h"
  
  #include <Eigen/Core>
  #include <Eigen/Geometry>
  
  #include <vector>
  #include <string>
  #include <cstdint>
  
  #define IGL_MOD_SHIFT           0x0001
  #define IGL_MOD_CONTROL         0x0002
  #define IGL_MOD_ALT             0x0004
  #define IGL_MOD_SUPER           0x0008
  
  struct GLFWwindow;
  
  namespace igl
  {
  namespace opengl
  {
  namespace glfw
  {
    // GLFW-based mesh viewer
    class Viewer
    {
    public:
      // UI Enumerations
      enum class MouseButton {Left, Middle, Right};
      enum class MouseMode { None, Rotation, Zoom, Pan, Translation} mouse_mode;
      IGL_INLINE int launch(bool resizable = true,bool fullscreen = false);
      IGL_INLINE int launch_init(bool resizable = true,bool fullscreen = false);
      IGL_INLINE bool launch_rendering(bool loop = true);
      IGL_INLINE void launch_shut();
      IGL_INLINE void init();
      IGL_INLINE void init_plugins();
      IGL_INLINE void shutdown_plugins();
      Viewer();
      ~Viewer();
      // Mesh IO
      IGL_INLINE bool load_mesh_from_file(const std::string & mesh_file_name);
      IGL_INLINE bool   save_mesh_to_file(const std::string & mesh_file_name);
      // Callbacks
      IGL_INLINE bool key_pressed(unsigned int unicode_key,int modifier);
      IGL_INLINE bool key_down(int key,int modifier);
      IGL_INLINE bool key_up(int key,int modifier);
      IGL_INLINE bool mouse_down(MouseButton button,int modifier);
      IGL_INLINE bool mouse_up(MouseButton button,int modifier);
      IGL_INLINE bool mouse_move(int mouse_x,int mouse_y);
      IGL_INLINE bool mouse_scroll(float delta_y);
      // Scene IO
      IGL_INLINE bool load_scene();
      IGL_INLINE bool load_scene(std::string fname);
      IGL_INLINE bool save_scene();
      IGL_INLINE bool save_scene(std::string fname);
      // Draw everything
      IGL_INLINE void draw();
      // OpenGL context resize
      IGL_INLINE void resize(int w,int h); // explicitly set window size
      IGL_INLINE void post_resize(int w,int h); // external resize due to user interaction
      // Helper functions
      IGL_INLINE void snap_to_canonical_quaternion();
      IGL_INLINE void open_dialog_load_mesh();
      IGL_INLINE void open_dialog_save_mesh();
      IGL_INLINE ViewerData& data();
  
      // Append a new "slot" for a mesh (i.e., create empty entires at the end of
      // the data_list and opengl_state_list.
      //
      // Returns the id of the last appended mesh
      //
      // Side Effects:
      //   selected_data_index is set this newly created, last entry (i.e.,
      //   #meshes-1)
      IGL_INLINE int append_mesh();
  
      // Erase a mesh (i.e., its corresponding data and state entires in data_list
      // and opengl_state_list)
      //
      // Inputs:
      //   index  index of mesh to erase
      // Returns whether erasure was successful <=> cannot erase last mesh
      //
      // Side Effects:
      //   If selected_data_index is greater than or equal to index then it is
      //   decremented
      // Example:
      //   // Erase all mesh slots except first and clear remaining mesh
      //   viewer.selected_data_index = viewer.data_list.size()-1;
      //   while(viewer.erase_mesh(viewer.selected_data_index)){};
      //   viewer.data().clear();
      //
      IGL_INLINE bool erase_mesh(const size_t index);
  
      // Retrieve mesh index from its unique identifier
      // Returns 0 if not found
      IGL_INLINE size_t mesh_index(const int id) const;
  
      // Alec: I call this data_list instead of just data to avoid confusion with
      // old "data" variable.
      // Stores all the data that should be visualized
      std::vector<ViewerData> data_list;
  
      size_t selected_data_index;
      int next_data_id;
      GLFWwindow* window;
      // Stores all the viewing options
      ViewerCore core;
      // List of registered plugins
      std::vector<ViewerPlugin*> plugins;
      // Temporary data stored when the mouse button is pressed
      Eigen::Quaternionf down_rotation;
      int current_mouse_x;
      int current_mouse_y;
      int down_mouse_x;
      int down_mouse_y;
      float down_mouse_z;
      Eigen::Vector3f down_translation;
      bool down;
      bool hack_never_moved;
      // Keep track of the global position of the scrollwheel
      float scroll_position;
      // C++-style functions
      //
      // Returns **true** if action should be cancelled.
      std::function<bool(Viewer& viewer)> callback_init;
      std::function<bool(Viewer& viewer)> callback_pre_draw;
      std::function<bool(Viewer& viewer)> callback_post_draw;
      std::function<bool(Viewer& viewer, int button, int modifier)> callback_mouse_down;
      std::function<bool(Viewer& viewer, int button, int modifier)> callback_mouse_up;
      std::function<bool(Viewer& viewer, int mouse_x, int mouse_y)> callback_mouse_move;
      std::function<bool(Viewer& viewer, float delta_y)> callback_mouse_scroll;
      std::function<bool(Viewer& viewer, unsigned int key, int modifiers)> callback_key_pressed;
      // THESE SHOULD BE DEPRECATED:
      std::function<bool(Viewer& viewer, unsigned int key, int modifiers)> callback_key_down;
      std::function<bool(Viewer& viewer, unsigned int key, int modifiers)> callback_key_up;
      // Pointers to per-callback data
      void* callback_init_data;
      void* callback_pre_draw_data;
      void* callback_post_draw_data;
      void* callback_mouse_down_data;
      void* callback_mouse_up_data;
      void* callback_mouse_move_data;
      void* callback_mouse_scroll_data;
      void* callback_key_pressed_data;
      void* callback_key_down_data;
      void* callback_key_up_data;
  
    public:
        EIGEN_MAKE_ALIGNED_OPERATOR_NEW
    };
  
  } // end namespace
  } // end namespace
  } // end namespace
  
  #ifndef IGL_STATIC_LIBRARY
  #  include "Viewer.cpp"
  #endif
  
  #endif
  