1 // Dear ImGui: standalone example application for GLUT/FreeGLUT + OpenGL2, using legacy fixed pipeline
2 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
3 // Read online: https://github.com/ocornut/imgui/tree/master/docs
4 
5 // !!! GLUT/FreeGLUT IS OBSOLETE PREHISTORIC SOFTWARE. Using GLUT is not recommended unless you really miss the 90's. !!!
6 // !!! If someone or something is teaching you GLUT today, you are being abused. Please show some resistance. !!!
7 // !!! Nowadays, prefer using GLFW or SDL instead!
8 
9 // On Windows, you can install Freeglut using vcpkg:
10 //   git clone https://github.com/Microsoft/vcpkg
11 //   cd vcpkg
12 //   bootstrap - vcpkg.bat
13 //   vcpkg install freeglut --triplet=x86-windows   ; for win32
14 //   vcpkg install freeglut --triplet=x64-windows   ; for win64
15 //   vcpkg integrate install                        ; register include and libs in Visual Studio
16 
17 #include "imgui.h"
18 #include "imgui_impl_glut.h"
19 #include "imgui_impl_opengl2.h"
20 #ifdef __APPLE__
21     #include <GLUT/glut.h>
22 #else
23     #include <GL/freeglut.h>
24 #endif
25 
26 #ifdef _MSC_VER
27 #pragma warning (disable: 4505) // unreferenced local function has been removed
28 #endif
29 
30 // Our state
31 static bool show_demo_window = true;
32 static bool show_another_window = false;
33 static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
34 
my_display_code()35 void my_display_code()
36 {
37     // 1. Show the big demo window (Most of the sample code is in ImGui::ShowDemoWindow()! You can browse its code to learn more about Dear ImGui!).
38     if (show_demo_window)
39         ImGui::ShowDemoWindow(&show_demo_window);
40 
41     // 2. Show a simple window that we create ourselves. We use a Begin/End pair to created a named window.
42     {
43         static float f = 0.0f;
44         static int counter = 0;
45 
46         ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
47 
48         ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
49         ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
50         ImGui::Checkbox("Another Window", &show_another_window);
51 
52         ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
53         ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
54 
55         if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
56             counter++;
57         ImGui::SameLine();
58         ImGui::Text("counter = %d", counter);
59 
60         ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
61         ImGui::End();
62     }
63 
64     // 3. Show another simple window.
65     if (show_another_window)
66     {
67         ImGui::Begin("Another Window", &show_another_window);   // Pass a pointer to our bool variable (the window will have a closing button that will clear the bool when clicked)
68         ImGui::Text("Hello from another window!");
69         if (ImGui::Button("Close Me"))
70             show_another_window = false;
71         ImGui::End();
72     }
73 }
74 
glut_display_func()75 void glut_display_func()
76 {
77     // Start the Dear ImGui frame
78     ImGui_ImplOpenGL2_NewFrame();
79     ImGui_ImplGLUT_NewFrame();
80 
81     my_display_code();
82 
83     // Rendering
84     ImGui::Render();
85     ImGuiIO& io = ImGui::GetIO();
86     glViewport(0, 0, (GLsizei)io.DisplaySize.x, (GLsizei)io.DisplaySize.y);
87     glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
88     glClear(GL_COLOR_BUFFER_BIT);
89     //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound, but prefer using the GL3+ code.
90     ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());
91 
92     glutSwapBuffers();
93     glutPostRedisplay();
94 }
95 
96 // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
97 // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
98 // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
99 // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
100 
main(int argc, char** argv)101 int main(int argc, char** argv)
102 {
103     // Create GLUT window
104     glutInit(&argc, argv);
105 #ifdef __FREEGLUT_EXT_H__
106     glutSetOption(GLUT_ACTION_ON_WINDOW_CLOSE, GLUT_ACTION_GLUTMAINLOOP_RETURNS);
107 #endif
108     glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_MULTISAMPLE);
109     glutInitWindowSize(1280, 720);
110     glutCreateWindow("Dear ImGui GLUT+OpenGL2 Example");
111 
112     // Setup GLUT display function
113     // We will also call ImGui_ImplGLUT_InstallFuncs() to get all the other functions installed for us,
114     // otherwise it is possible to install our own functions and call the imgui_impl_glut.h functions ourselves.
115     glutDisplayFunc(glut_display_func);
116 
117     // Setup Dear ImGui context
118     IMGUI_CHECKVERSION();
119     ImGui::CreateContext();
120     ImGuiIO& io = ImGui::GetIO(); (void)io;
121     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
122 
123     // Setup Dear ImGui style
124     ImGui::StyleColorsDark();
125     //ImGui::StyleColorsClassic();
126 
127     // Setup Platform/Renderer backends
128     ImGui_ImplGLUT_Init();
129     ImGui_ImplGLUT_InstallFuncs();
130     ImGui_ImplOpenGL2_Init();
131 
132     // Load Fonts
133     // - If no fonts are loaded, dear imgui will use the default font. You can also load multiple fonts and use ImGui::PushFont()/PopFont() to select them.
134     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple.
135     // - If the file cannot be loaded, the function will return NULL. Please handle those errors in your application (e.g. use an assertion, or display an error and quit).
136     // - The fonts will be rasterized at a given size (w/ oversampling) and stored into a texture when calling ImFontAtlas::Build()/GetTexDataAsXXXX(), which ImGui_ImplXXXX_NewFrame below will call.
137     // - Read 'docs/FONTS.md' for more instructions and details.
138     // - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
139     //io.Fonts->AddFontDefault();
140     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
141     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
142     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
143     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/ProggyTiny.ttf", 10.0f);
144     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
145     //IM_ASSERT(font != NULL);
146 
147     glutMainLoop();
148 
149     // Cleanup
150     ImGui_ImplOpenGL2_Shutdown();
151     ImGui_ImplGLUT_Shutdown();
152     ImGui::DestroyContext();
153 
154     return 0;
155 }
156