examples/example_sdl_opengl3/main.cpp - external/github.com/ocornut/imgui - Git at Google

 // ImGui - standalone example application for SDL2 + OpenGL
 // If you are new to ImGui, see examples/README.txt and documentation at the top of imgui.cpp.
 // (SDL is a cross-platform general purpose library for handling windows, inputs, OpenGL/Vulkan graphics context creation, etc.)
 // (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.)

 #include "imgui.h"
 #include "imgui_impl_sdl.h"
 #include "imgui_impl_opengl3.h"
 #include <stdio.h>
 #include <GL/gl3w.h>    // This example is using gl3w to access OpenGL functions. You may freely use any other OpenGL loader such as: glew, glad, glLoadGen, etc.
 //#include <glew.h>
 #include <SDL.h>

 int main(int, char**)
 {
     // Setup SDL
     if (SDL_Init(SDL_INIT_VIDEO|SDL_INIT_TIMER) != 0)
     {
         printf("Error: %s\n", SDL_GetError());
         return -1;
     }

     // Setup window
     SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG);
     SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
     SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
     SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
     SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
     SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
     SDL_DisplayMode current;
     SDL_GetCurrentDisplayMode(0, &current);
     SDL_Window* window = SDL_CreateWindow("ImGui SDL2+OpenGL3 example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);
     SDL_GLContext gl_context = SDL_GL_CreateContext(window);
     SDL_GL_SetSwapInterval(1); // Enable vsync
     gl3wInit();

     // Setup Dear ImGui binding
     IMGUI_CHECKVERSION();
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     //io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls

     ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
     ImGui_ImplOpenGL3_Init();

     // Setup style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsClassic();

     // Load Fonts
     // - 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.
     // - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple.
     // - 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).
     // - 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.
     // - Read 'misc/fonts/README.txt' for more instructions and details.
     // - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
     //io.Fonts->AddFontDefault();
     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/ProggyTiny.ttf", 10.0f);
     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);

     bool show_demo_window = true;
     bool show_another_window = false;
     ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);

     // Main loop
     bool done = false;
     while (!done)
     {
         // Poll and handle events (inputs, window resize, etc.)
         // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
         // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
         SDL_Event event;
         while (SDL_PollEvent(&event))
         {
             ImGui_ImplSDL2_ProcessEvent(&event);
             if (event.type == SDL_QUIT)
                 done = true;
             if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
                 done = true;
         }

         // Start the ImGui frame
         ImGui_ImplOpenGL3_NewFrame();
         ImGui_ImplSDL2_NewFrame(window);
         ImGui::NewFrame();

         // 1. Show a simple window.
         // Tip: if we don't call ImGui::Begin()/ImGui::End() the widgets automatically appears in a window called "Debug".
         {
             static float f = 0.0f;
             static int counter = 0;
             ImGui::Text("Hello, world!");                           // Display some text (you can use a format string too)
             ImGui::SliderFloat("float", &f, 0.0f, 1.0f);            // Edit 1 float using a slider from 0.0f to 1.0f
             ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color

             ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our windows open/close state
             ImGui::Checkbox("Another Window", &show_another_window);

             if (ImGui::Button("Button"))                            // Buttons return true when clicked (NB: most widgets return true when edited/activated)
                 counter++;
             ImGui::SameLine();
             ImGui::Text("counter = %d", counter);

             ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
         }

         // 2. Show another simple window. In most cases you will use an explicit Begin/End pair to name your windows.
         if (show_another_window)
         {
             ImGui::Begin("Another Window", &show_another_window);
             ImGui::Text("Hello from another window!");
             if (ImGui::Button("Close Me"))
                 show_another_window = false;
             ImGui::End();
         }

         // 3. Show the ImGui demo window. Most of the sample code is in ImGui::ShowDemoWindow(). Read its code to learn more about Dear ImGui!
         if (show_demo_window)
         {
             ImGui::SetNextWindowPos(ImVec2(650, 20), ImGuiCond_FirstUseEver); // Normally user code doesn't need/want to call this because positions are saved in .ini file anyway. Here we just want to make the demo initial state a bit more friendly!
             ImGui::ShowDemoWindow(&show_demo_window);
         }

         // Rendering
         ImGui::Render();
         SDL_GL_MakeCurrent(window, gl_context);
         glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
         glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
         glClear(GL_COLOR_BUFFER_BIT);
         ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
         SDL_GL_SwapWindow(window);
     }

     // Cleanup
     ImGui_ImplOpenGL3_Shutdown();
     ImGui_ImplSDL2_Shutdown();
     ImGui::DestroyContext();

     SDL_GL_DeleteContext(gl_context);
     SDL_DestroyWindow(window);
     SDL_Quit();

     return 0;
 }
	// ImGui - standalone example application for SDL2 + OpenGL
	// If you are new to ImGui, see examples/README.txt and documentation at the top of imgui.cpp.
	// (SDL is a cross-platform general purpose library for handling windows, inputs, OpenGL/Vulkan graphics context creation, etc.)
	// (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.)

	#include "imgui.h"
	#include "imgui_impl_sdl.h"
	#include "imgui_impl_opengl3.h"
	#include <stdio.h>
	#include <GL/gl3w.h> // This example is using gl3w to access OpenGL functions. You may freely use any other OpenGL loader such as: glew, glad, glLoadGen, etc.
	//#include <glew.h>
	#include <SDL.h>

	int main(int, char**)
	{
	// Setup SDL
	if (SDL_Init(SDL_INIT_VIDEO\|SDL_INIT_TIMER) != 0)
	{
	printf("Error: %s\n", SDL_GetError());
	return -1;
	}

	// Setup window
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
	SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
	SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
	SDL_DisplayMode current;
	SDL_GetCurrentDisplayMode(0, &current);
	SDL_Window* window = SDL_CreateWindow("ImGui SDL2+OpenGL3 example", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 1280, 720, SDL_WINDOW_OPENGL\|SDL_WINDOW_RESIZABLE);
	SDL_GLContext gl_context = SDL_GL_CreateContext(window);
	SDL_GL_SetSwapInterval(1); // Enable vsync
	gl3wInit();

	// Setup Dear ImGui binding
	IMGUI_CHECKVERSION();
	ImGui::CreateContext();
	ImGuiIO& io = ImGui::GetIO(); (void)io;
	//io.ConfigFlags \|= ImGuiConfigFlags_NavEnableKeyboard; // Enable Keyboard Controls

	ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
	ImGui_ImplOpenGL3_Init();

	// Setup style
	ImGui::StyleColorsDark();
	//ImGui::StyleColorsClassic();

	// Load Fonts
	// - 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.
	// - AddFontFromFileTTF() will return the ImFont* so you can store it if you need to select the font among multiple.
	// - 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).
	// - 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.
	// - Read 'misc/fonts/README.txt' for more instructions and details.
	// - Remember that in C/C++ if you want to include a backslash \ in a string literal you need to write a double backslash \\ !
	//io.Fonts->AddFontDefault();
	//io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
	//io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
	//io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
	//io.Fonts->AddFontFromFileTTF("../../misc/fonts/ProggyTiny.ttf", 10.0f);
	//ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
	//IM_ASSERT(font != NULL);

	bool show_demo_window = true;
	bool show_another_window = false;
	ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);

	// Main loop
	bool done = false;
	while (!done)
	{
	// Poll and handle events (inputs, window resize, etc.)
	// You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
	// - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
	// - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
	// Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
	SDL_Event event;
	while (SDL_PollEvent(&event))
	{
	ImGui_ImplSDL2_ProcessEvent(&event);
	if (event.type == SDL_QUIT)
	done = true;
	if (event.type == SDL_WINDOWEVENT && event.window.event == SDL_WINDOWEVENT_CLOSE && event.window.windowID == SDL_GetWindowID(window))
	done = true;
	}

	// Start the ImGui frame
	ImGui_ImplOpenGL3_NewFrame();
	ImGui_ImplSDL2_NewFrame(window);
	ImGui::NewFrame();

	// 1. Show a simple window.
	// Tip: if we don't call ImGui::Begin()/ImGui::End() the widgets automatically appears in a window called "Debug".
	{
	static float f = 0.0f;
	static int counter = 0;
	ImGui::Text("Hello, world!"); // Display some text (you can use a format string too)
	ImGui::SliderFloat("float", &f, 0.0f, 1.0f); // Edit 1 float using a slider from 0.0f to 1.0f
	ImGui::ColorEdit3("clear color", (float*)&clear_color); // Edit 3 floats representing a color

	ImGui::Checkbox("Demo Window", &show_demo_window); // Edit bools storing our windows open/close state
	ImGui::Checkbox("Another Window", &show_another_window);

	if (ImGui::Button("Button")) // Buttons return true when clicked (NB: most widgets return true when edited/activated)
	counter++;
	ImGui::SameLine();
	ImGui::Text("counter = %d", counter);

	ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
	}

	// 2. Show another simple window. In most cases you will use an explicit Begin/End pair to name your windows.
	if (show_another_window)
	{
	ImGui::Begin("Another Window", &show_another_window);
	ImGui::Text("Hello from another window!");
	if (ImGui::Button("Close Me"))
	show_another_window = false;
	ImGui::End();
	}

	// 3. Show the ImGui demo window. Most of the sample code is in ImGui::ShowDemoWindow(). Read its code to learn more about Dear ImGui!
	if (show_demo_window)
	{
	ImGui::SetNextWindowPos(ImVec2(650, 20), ImGuiCond_FirstUseEver); // Normally user code doesn't need/want to call this because positions are saved in .ini file anyway. Here we just want to make the demo initial state a bit more friendly!
	ImGui::ShowDemoWindow(&show_demo_window);
	}

	// Rendering
	ImGui::Render();
	SDL_GL_MakeCurrent(window, gl_context);
	glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
	glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
	glClear(GL_COLOR_BUFFER_BIT);
	ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
	SDL_GL_SwapWindow(window);
	}

	// Cleanup
	ImGui_ImplOpenGL3_Shutdown();
	ImGui_ImplSDL2_Shutdown();
	ImGui::DestroyContext();

	SDL_GL_DeleteContext(gl_context);
	SDL_DestroyWindow(window);
	SDL_Quit();

	return 0;
	}