examples/example_win32_opengl3/main.cpp - external/github.com/ocornut/imgui - Git at Google

 // Dear ImGui: standalone example application for Win32 + OpenGL 3
 // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
 // Read online: https://github.com/ocornut/imgui/tree/master/docs

 // This is provided for completeness, however it is strogly recommended you use OpenGL with SDL or GLFW.

 #include "imgui.h"
 #include "imgui_impl_opengl3.h"
 #include "imgui_impl_win32.h"
 #ifndef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN
 #endif
 #include <windows.h>
 #include <GL/GL.h>
 #include <tchar.h>

 // Data stored per platform window
 struct WGL_WindowData { HDC hDC; };

 // Data
 static HGLRC            g_hRC;
 static WGL_WindowData   g_MainWindow;
 static int              g_Width;
 static int              g_Height;

 // Forward declarations of helper functions
 bool CreateDeviceWGL(HWND hWnd, WGL_WindowData* data);
 void CleanupDeviceWGL(HWND hWnd, WGL_WindowData* data);
 void ResetDeviceWGL();
 LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);

 // Main code
 int main(int, char**)
 {
     // Create application window
     //ImGui_ImplWin32_EnableDpiAwareness();
     WNDCLASSEXW wc = { sizeof(wc), CS_OWNDC, WndProc, 0L, 0L, GetModuleHandle(NULL), NULL, NULL, NULL, NULL, L"ImGui Example", NULL };
     ::RegisterClassExW(&wc);
     HWND hwnd = ::CreateWindowW(wc.lpszClassName, L"Dear ImGui Win32+OpenGL3 Example", WS_OVERLAPPEDWINDOW, 100, 100, 1280, 800, NULL, NULL, wc.hInstance, NULL);

     // Initialize OpenGL
     if (!CreateDeviceWGL(hwnd, &g_MainWindow))
     {
         CleanupDeviceWGL(hwnd, &g_MainWindow);
         ::DestroyWindow(hwnd);
         ::UnregisterClassW(wc.lpszClassName, wc.hInstance);
         return 1;
     }
     wglMakeCurrent(g_MainWindow.hDC, g_hRC);

     // Show the window
     ::ShowWindow(hwnd, SW_SHOWDEFAULT);
     ::UpdateWindow(hwnd);

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

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

     // Setup Platform/Renderer backends
     ImGui_ImplWin32_InitForOpenGL(hwnd);
     ImGui_ImplOpenGL3_Init();

     // 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.
     // - Use '#define IMGUI_ENABLE_FREETYPE' in your imconfig file to use Freetype for higher quality font rendering.
     // - Read 'docs/FONTS.md' 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("c:\\Windows\\Fonts\\segoeui.ttf", 18.0f);
     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
     //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
     //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
     //IM_ASSERT(font != NULL);

     // Our state
     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 messages (inputs, window resize, etc.)
         // See the WndProc() function below for our to dispatch events to the Win32 backend.
         MSG msg;
         while (::PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
         {
             ::TranslateMessage(&msg);
             ::DispatchMessage(&msg);
             if (msg.message == WM_QUIT)
                 done = true;
         }
         if (done)
             break;

         // Start the Dear ImGui frame
         ImGui_ImplOpenGL3_NewFrame();
         ImGui_ImplWin32_NewFrame();
         ImGui::NewFrame();

         // 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!).
         if (show_demo_window)
             ImGui::ShowDemoWindow(&show_demo_window);

         // 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
         {
             static float f = 0.0f;
             static int counter = 0;

             ImGui::Begin("Hello, world!");                          // Create a window called "Hello, world!" and append into it.

             ImGui::Text("This is some useful text.");               // Display some text (you can use a format strings too)
             ImGui::Checkbox("Demo Window", &show_demo_window);      // Edit bools storing our window open/close state
             ImGui::Checkbox("Another Window", &show_another_window);

             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

             if (ImGui::Button("Button"))                            // Buttons return true when clicked (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 / io.Framerate, io.Framerate);
             ImGui::End();
         }

         // 3. Show another simple window.
         if (show_another_window)
         {
             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)
             ImGui::Text("Hello from another window!");
             if (ImGui::Button("Close Me"))
                 show_another_window = false;
             ImGui::End();
         }

         // Rendering
         ImGui::Render();
         glViewport(0, 0, g_Width, g_Height);
         glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
         glClear(GL_COLOR_BUFFER_BIT);
         ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

         // Present
         ::SwapBuffers(g_MainWindow.hDC);
     }

     ImGui_ImplOpenGL3_Shutdown();
     ImGui_ImplWin32_Shutdown();
     ImGui::DestroyContext();

     CleanupDeviceWGL(hwnd, &g_MainWindow);
     wglDeleteContext(g_hRC);
     ::DestroyWindow(hwnd);
     ::UnregisterClassW(wc.lpszClassName, wc.hInstance);

     return 0;
 }

 // Helper functions
 bool CreateDeviceWGL(HWND hWnd, WGL_WindowData* data)
 {
     HDC hDc = ::GetDC(hWnd);
     PIXELFORMATDESCRIPTOR pfd = { 0 };
     pfd.nSize = sizeof(pfd);
     pfd.nVersion = 1;
     pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;
     pfd.iPixelType = PFD_TYPE_RGBA;
     pfd.cColorBits = 32;

     const int pf = ::ChoosePixelFormat(hDc, &pfd);
     if (pf == 0)
         return false;
     if (::SetPixelFormat(hDc, pf, &pfd) == FALSE)
         return false;
     ::ReleaseDC(hWnd, hDc);

     data->hDC = ::GetDC(hWnd);
     if (!g_hRC)
         g_hRC = wglCreateContext(data->hDC);
     return true;
 }

 void CleanupDeviceWGL(HWND hWnd, WGL_WindowData* data)
 {
     wglMakeCurrent(NULL, NULL);
     ::ReleaseDC(hWnd, data->hDC);
 }

 // Forward declare message handler from imgui_impl_win32.cpp
 extern IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);

 // Win32 message handler
 // 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, or clear/overwrite your copy of the mouse data.
 // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
 // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
 LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
 {
     if (ImGui_ImplWin32_WndProcHandler(hWnd, msg, wParam, lParam))
         return true;

     switch (msg)
     {
     case WM_SIZE:
         if (wParam != SIZE_MINIMIZED)
         {
             g_Width = LOWORD(lParam);
             g_Height = HIWORD(lParam);
         }
         return 0;
     case WM_SYSCOMMAND:
         if ((wParam & 0xfff0) == SC_KEYMENU) // Disable ALT application menu
             return 0;
         break;
     case WM_DESTROY:
         ::PostQuitMessage(0);
         return 0;
     }
     return ::DefWindowProc(hWnd, msg, wParam, lParam);
 }
	// Dear ImGui: standalone example application for Win32 + OpenGL 3
	// If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
	// Read online: https://github.com/ocornut/imgui/tree/master/docs

	// This is provided for completeness, however it is strogly recommended you use OpenGL with SDL or GLFW.

	#include "imgui.h"
	#include "imgui_impl_opengl3.h"
	#include "imgui_impl_win32.h"
	#ifndef WIN32_LEAN_AND_MEAN
	#define WIN32_LEAN_AND_MEAN
	#endif
	#include <windows.h>
	#include <GL/GL.h>
	#include <tchar.h>

	// Data stored per platform window
	struct WGL_WindowData { HDC hDC; };

	// Data
	static HGLRC g_hRC;
	static WGL_WindowData g_MainWindow;
	static int g_Width;
	static int g_Height;

	// Forward declarations of helper functions
	bool CreateDeviceWGL(HWND hWnd, WGL_WindowData* data);
	void CleanupDeviceWGL(HWND hWnd, WGL_WindowData* data);
	void ResetDeviceWGL();
	LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);

	// Main code
	int main(int, char**)
	{
	// Create application window
	//ImGui_ImplWin32_EnableDpiAwareness();
	WNDCLASSEXW wc = { sizeof(wc), CS_OWNDC, WndProc, 0L, 0L, GetModuleHandle(NULL), NULL, NULL, NULL, NULL, L"ImGui Example", NULL };
	::RegisterClassExW(&wc);
	HWND hwnd = ::CreateWindowW(wc.lpszClassName, L"Dear ImGui Win32+OpenGL3 Example", WS_OVERLAPPEDWINDOW, 100, 100, 1280, 800, NULL, NULL, wc.hInstance, NULL);

	// Initialize OpenGL
	if (!CreateDeviceWGL(hwnd, &g_MainWindow))
	{
	CleanupDeviceWGL(hwnd, &g_MainWindow);
	::DestroyWindow(hwnd);
	::UnregisterClassW(wc.lpszClassName, wc.hInstance);
	return 1;
	}
	wglMakeCurrent(g_MainWindow.hDC, g_hRC);

	// Show the window
	::ShowWindow(hwnd, SW_SHOWDEFAULT);
	::UpdateWindow(hwnd);

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

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

	// Setup Platform/Renderer backends
	ImGui_ImplWin32_InitForOpenGL(hwnd);
	ImGui_ImplOpenGL3_Init();

	// 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.
	// - Use '#define IMGUI_ENABLE_FREETYPE' in your imconfig file to use Freetype for higher quality font rendering.
	// - Read 'docs/FONTS.md' 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("c:\\Windows\\Fonts\\segoeui.ttf", 18.0f);
	//io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf", 16.0f);
	//io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf", 16.0f);
	//io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf", 15.0f);
	//ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
	//IM_ASSERT(font != NULL);

	// Our state
	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 messages (inputs, window resize, etc.)
	// See the WndProc() function below for our to dispatch events to the Win32 backend.
	MSG msg;
	while (::PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
	{
	::TranslateMessage(&msg);
	::DispatchMessage(&msg);
	if (msg.message == WM_QUIT)
	done = true;
	}
	if (done)
	break;

	// Start the Dear ImGui frame
	ImGui_ImplOpenGL3_NewFrame();
	ImGui_ImplWin32_NewFrame();
	ImGui::NewFrame();

	// 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!).
	if (show_demo_window)
	ImGui::ShowDemoWindow(&show_demo_window);

	// 2. Show a simple window that we create ourselves. We use a Begin/End pair to create a named window.
	{
	static float f = 0.0f;
	static int counter = 0;

	ImGui::Begin("Hello, world!"); // Create a window called "Hello, world!" and append into it.

	ImGui::Text("This is some useful text."); // Display some text (you can use a format strings too)
	ImGui::Checkbox("Demo Window", &show_demo_window); // Edit bools storing our window open/close state
	ImGui::Checkbox("Another Window", &show_another_window);

	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

	if (ImGui::Button("Button")) // Buttons return true when clicked (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 / io.Framerate, io.Framerate);
	ImGui::End();
	}

	// 3. Show another simple window.
	if (show_another_window)
	{
	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)
	ImGui::Text("Hello from another window!");
	if (ImGui::Button("Close Me"))
	show_another_window = false;
	ImGui::End();
	}

	// Rendering
	ImGui::Render();
	glViewport(0, 0, g_Width, g_Height);
	glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
	glClear(GL_COLOR_BUFFER_BIT);
	ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

	// Present
	::SwapBuffers(g_MainWindow.hDC);
	}

	ImGui_ImplOpenGL3_Shutdown();
	ImGui_ImplWin32_Shutdown();
	ImGui::DestroyContext();

	CleanupDeviceWGL(hwnd, &g_MainWindow);
	wglDeleteContext(g_hRC);
	::DestroyWindow(hwnd);
	::UnregisterClassW(wc.lpszClassName, wc.hInstance);

	return 0;
	}

	// Helper functions
	bool CreateDeviceWGL(HWND hWnd, WGL_WindowData* data)
	{
	HDC hDc = ::GetDC(hWnd);
	PIXELFORMATDESCRIPTOR pfd = { 0 };
	pfd.nSize = sizeof(pfd);
	pfd.nVersion = 1;
	pfd.dwFlags = PFD_DRAW_TO_WINDOW \| PFD_SUPPORT_OPENGL \| PFD_DOUBLEBUFFER;
	pfd.iPixelType = PFD_TYPE_RGBA;
	pfd.cColorBits = 32;

	const int pf = ::ChoosePixelFormat(hDc, &pfd);
	if (pf == 0)
	return false;
	if (::SetPixelFormat(hDc, pf, &pfd) == FALSE)
	return false;
	::ReleaseDC(hWnd, hDc);

	data->hDC = ::GetDC(hWnd);
	if (!g_hRC)
	g_hRC = wglCreateContext(data->hDC);
	return true;
	}

	void CleanupDeviceWGL(HWND hWnd, WGL_WindowData* data)
	{
	wglMakeCurrent(NULL, NULL);
	::ReleaseDC(hWnd, data->hDC);
	}

	// Forward declare message handler from imgui_impl_win32.cpp
	extern IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);

	// Win32 message handler
	// 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, or clear/overwrite your copy of the mouse data.
	// - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
	// Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
	LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
	{
	if (ImGui_ImplWin32_WndProcHandler(hWnd, msg, wParam, lParam))
	return true;

	switch (msg)
	{
	case WM_SIZE:
	if (wParam != SIZE_MINIMIZED)
	{
	g_Width = LOWORD(lParam);
	g_Height = HIWORD(lParam);
	}
	return 0;
	case WM_SYSCOMMAND:
	if ((wParam & 0xfff0) == SC_KEYMENU) // Disable ALT application menu
	return 0;
	break;
	case WM_DESTROY:
	::PostQuitMessage(0);
	return 0;
	}
	return ::DefWindowProc(hWnd, msg, wParam, lParam);
	}