1 // Dear ImGui: standalone example application for SDL2 + OpenGL
2 // (SDL is a cross-platform general purpose library for handling windows, inputs, OpenGL/Vulkan/Metal graphics context creation, etc.)
3 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
4 // Read online: https://github.com/ocornut/imgui/tree/master/docs
5 
6 // **DO NOT USE THIS CODE IF YOUR CODE/ENGINE IS USING MODERN OPENGL (SHADERS, VBO, VAO, etc.)**
7 // **Prefer using the code in the example_sdl_opengl3/ folder**
8 // See imgui_impl_sdl.cpp for details.
9 
10 #include "imgui.h"
11 #include "imgui_impl_sdl.h"
12 #include "imgui_impl_opengl2.h"
13 #include <stdio.h>
14 #include <SDL.h>
15 #include <SDL_opengl.h>
16 
17 // Main code
main(int,char **)18 int main(int, char**)
19 {
20     // Setup SDL
21     // (Some versions of SDL before <2.0.10 appears to have performance/stalling issues on a minority of Windows systems,
22     // depending on whether SDL_INIT_GAMECONTROLLER is enabled or disabled.. updating to latest version of SDL is recommended!)
23     if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_TIMER | SDL_INIT_GAMECONTROLLER) != 0)
24     {
25         printf("Error: %s\n", SDL_GetError());
26         return -1;
27     }
28 
29     // Setup window
30     SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
31     SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
32     SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
33     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
34     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
35     SDL_WindowFlags window_flags = (SDL_WindowFlags)(SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE | SDL_WINDOW_ALLOW_HIGHDPI);
36     SDL_Window* window = SDL_CreateWindow("Dear ImGui SDL2+OpenGL example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, window_flags);
37     SDL_GLContext gl_context = SDL_GL_CreateContext(window);
38     SDL_GL_MakeCurrent(window, gl_context);
39     SDL_GL_SetSwapInterval(1); // Enable vsync
40 
41     // Setup Dear ImGui context
42     IMGUI_CHECKVERSION();
43     ImGui::CreateContext();
44     ImGuiIO& io = ImGui::GetIO(); (void)io;
45     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;       // Enable Keyboard Controls
46     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
47     io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;           // Enable Docking
48     io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;         // Enable Multi-Viewport / Platform Windows
49     //io.ConfigViewportsNoAutoMerge = true;
50     //io.ConfigViewportsNoTaskBarIcon = true;
51 
52     // Setup Dear ImGui style
53     ImGui::StyleColorsDark();
54     //ImGui::StyleColorsClassic();
55 
56     // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
57     ImGuiStyle& style = ImGui::GetStyle();
58     if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
59     {
60         style.WindowRounding = 0.0f;
61         style.Colors[ImGuiCol_WindowBg].w = 1.0f;
62     }
63 
64     // Setup Platform/Renderer backends
65     ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
66     ImGui_ImplOpenGL2_Init();
67 
68     // Load Fonts
69     // - 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.
70     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple.
71     // - 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).
72     // - 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.
73     // - Read 'docs/FONTS.md' for more instructions and details.
74     // - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
75     //io.Fonts->AddFontDefault();
76     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
77     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
78     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
79     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/ProggyTiny.ttf", 10.0f);
80     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
81     //IM_ASSERT(font != NULL);
82 
83     // Our state
84     bool show_demo_window = true;
85     bool show_another_window = false;
86     ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
87 
88     // Main loop
89     bool done = false;
90     while (!done)
91     {
92         // Poll and handle events (inputs, window resize, etc.)
93         // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
94         // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
95         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
96         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
97         SDL_Event event;
98         while (SDL_PollEvent(&event))
99         {
100             ImGui_ImplSDL2_ProcessEvent(&event);
101             if (event.type == SDL_QUIT)
102                 done = true;
103             if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
104                 done = true;
105         }
106 
107         // Start the Dear ImGui frame
108         ImGui_ImplOpenGL2_NewFrame();
109         ImGui_ImplSDL2_NewFrame();
110         ImGui::NewFrame();
111 
112         // 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!).
113         if (show_demo_window)
114             ImGui::ShowDemoWindow(&show_demo_window);
115 
116         // 2. Show a simple window that we create ourselves. We use a Begin/End pair to created a named window.
117         {
118             static float f = 0.0f;
119             static int counter = 0;
120 
121             ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.
122 
123             ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
124             ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
125             ImGui::Checkbox("Another Window", &show_another_window);
126 
127             ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
128             ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color
129 
130             if (ImGui::Button("Button"))                            // Buttons return true when clicked (most widgets return true when edited/activated)
131                 counter++;
132             ImGui::SameLine();
133             ImGui::Text("counter = %d", counter);
134 
135             ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
136             ImGui::End();
137         }
138 
139         // 3. Show another simple window.
140         if (show_another_window)
141         {
142             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)
143             ImGui::Text("Hello from another window!");
144             if (ImGui::Button("Close Me"))
145                 show_another_window = false;
146             ImGui::End();
147         }
148 
149         // Rendering
150         ImGui::Render();
151         glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
152         glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
153         glClear(GL_COLOR_BUFFER_BIT);
154         //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound
155         ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());
156 
157         // Update and Render additional Platform Windows
158         // (Platform functions may change the current OpenGL context, so we save/restore it to make it easier to paste this code elsewhere.
159         //  For this specific demo app we could also call SDL_GL_MakeCurrent(window, gl_context) directly)
160         if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
161         {
162             SDL_Window* backup_current_window = SDL_GL_GetCurrentWindow();
163             SDL_GLContext backup_current_context = SDL_GL_GetCurrentContext();
164             ImGui::UpdatePlatformWindows();
165             ImGui::RenderPlatformWindowsDefault();
166             SDL_GL_MakeCurrent(backup_current_window, backup_current_context);
167         }
168 
169         SDL_GL_SwapWindow(window);
170     }
171 
172     // Cleanup
173     ImGui_ImplOpenGL2_Shutdown();
174     ImGui_ImplSDL2_Shutdown();
175     ImGui::DestroyContext();
176 
177     SDL_GL_DeleteContext(gl_context);
178     SDL_DestroyWindow(window);
179     SDL_Quit();
180 
181     return 0;
182 }
183