1 // ImGui - standalone example application for SDL2 + OpenGL
2 // If you are new to ImGui, see examples/README.txt and documentation at the top of imgui.cpp.
3 // (SDL is a cross-platform general purpose library for handling windows, inputs, OpenGL/Vulkan graphics context creation, etc.)
4 // (GL3W is a helper library to access OpenGL functions since there is no standard header to access modern OpenGL functions easily. Alternatives are GLEW, Glad, etc.)
5 
6 #include "imgui.h"
7 #include "imgui_impl_sdl.h"
8 #include "imgui_impl_opengl3.h"
9 #include <stdio.h>
10 #include <SDL.h>
11 
12 // About OpenGL function loaders: modern OpenGL doesn't have a standard header file and requires individual function pointers to be loaded manually.
13 // Helper libraries are often used for this purpose! Here we are supporting a few common ones: gl3w, glew, glad.
14 // You may use another loader/header of your choice (glext, glLoadGen, etc.), or chose to manually implement your own.
15 #if defined(IMGUI_IMPL_OPENGL_LOADER_GL3W)
16 #include <GL/gl3w.h>    // Initialize with gl3wInit()
17 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLEW)
18 #include <GL/glew.h>    // Initialize with glewInit()
19 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
20 #include <glad/glad.h>  // Initialize with gladLoadGL()
21 #else
22 #include IMGUI_IMPL_OPENGL_LOADER_CUSTOM
23 #endif
24 
main(int,char **)25 int main(int, char**)
26 {
27     // Setup SDL
28     if (SDL_Init(SDL_INIT_VIDEO|SDL_INIT_TIMER) != 0)
29     {
30         printf("Error: %s\n", SDL_GetError());
31         return -1;
32     }
33 
34     // Decide GL+GLSL versions
35 #if __APPLE__
36     // GL 3.2 Core + GLSL 150
37     const char* glsl_version = "#version 150";
38     SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG); // Always required on Mac
39     SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
40     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
41     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
42 #else
43     // GL 3.0 + GLSL 130
44     const char* glsl_version = "#version 130";
45     SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
46     SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
47     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
48     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
49 #endif
50 
51     // Create window with graphics context
52     SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
53     SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
54     SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
55     SDL_DisplayMode current;
56     SDL_GetCurrentDisplayMode(0, &current);
57     SDL_Window* window = SDL_CreateWindow("Dear ImGui SDL2+OpenGL3 example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
58     SDL_GLContext gl_context = SDL_GL_CreateContext(window);
59     SDL_GL_SetSwapInterval(1); // Enable vsync
60 
61     // Initialize OpenGL loader
62 #if defined(IMGUI_IMPL_OPENGL_LOADER_GL3W)
63     bool err = gl3wInit() != 0;
64 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLEW)
65     bool err = glewInit() != GLEW_OK;
66 #elif defined(IMGUI_IMPL_OPENGL_LOADER_GLAD)
67     bool err = gladLoadGL() == 0;
68 #endif
69     if (err)
70     {
71         fprintf(stderr, "Failed to initialize OpenGL loader!\n");
72         return 1;
73     }
74 
75     // Setup Dear ImGui binding
76     IMGUI_CHECKVERSION();
77     ImGui::CreateContext();
78     ImGuiIO& io = ImGui::GetIO(); (void)io;
79     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
80 
81     ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
82     ImGui_ImplOpenGL3_Init(glsl_version);
83 
84     // Setup style
85     ImGui::StyleColorsDark();
86     //ImGui::StyleColorsClassic();
87 
88     // Load Fonts
89     // - 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.
90     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple.
91     // - 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).
92     // - 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.
93     // - Read 'misc/fonts/README.txt' for more instructions and details.
94     // - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
95     //io.Fonts->AddFontDefault();
96     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
97     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
98     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
99     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/ProggyTiny.ttf", 10.0f);
100     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
101     //IM_ASSERT(font != NULL);
102 
103     bool show_demo_window = true;
104     bool show_another_window = false;
105     ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
106 
107     // Main loop
108     bool done = false;
109     while (!done)
110     {
111         // Poll and handle events (inputs, window resize, etc.)
112         // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
113         // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
114         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
115         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
116         SDL_Event event;
117         while (SDL_PollEvent(&event))
118         {
119             ImGui_ImplSDL2_ProcessEvent(&event);
120             if (event.type == SDL_QUIT)
121                 done = true;
122             if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
123                 done = true;
124         }
125 
126         // Start the Dear ImGui frame
127         ImGui_ImplOpenGL3_NewFrame();
128         ImGui_ImplSDL2_NewFrame(window);
129         ImGui::NewFrame();
130 
131         // 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!).
132         if (show_demo_window)
133             ImGui::ShowDemoWindow(&show_demo_window);
134 
135         // 2. Show a simple window that we create ourselves. We use a Begin/End pair to created a named window.
136         {
137             static float f = 0.0f;
138             static int counter = 0;
139 
140             ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
141 
142             ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
143             ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
144             ImGui::Checkbox("Another Window", &show_another_window);
145 
146             ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
147             ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
148 
149             if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
150                 counter++;
151             ImGui::SameLine();
152             ImGui::Text("counter = %d", counter);
153 
154             ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
155             ImGui::End();
156         }
157 
158         // 3. Show another simple window.
159         if (show_another_window)
160         {
161             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)
162             ImGui::Text("Hello from another window!");
163             if (ImGui::Button("Close Me"))
164                 show_another_window = false;
165             ImGui::End();
166         }
167 
168         // Rendering
169         ImGui::Render();
170         SDL_GL_MakeCurrent(window, gl_context);
171         glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
172         glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
173         glClear(GL_COLOR_BUFFER_BIT);
174         ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
175         SDL_GL_SwapWindow(window);
176     }
177 
178     // Cleanup
179     ImGui_ImplOpenGL3_Shutdown();
180     ImGui_ImplSDL2_Shutdown();
181     ImGui::DestroyContext();
182 
183     SDL_GL_DeleteContext(gl_context);
184     SDL_DestroyWindow(window);
185     SDL_Quit();
186 
187     return 0;
188 }
189