examples/example_apple_opengl3/main.mm

// Dear ImGui: standalone example application for OSX + OpenGL3

// Learn about Dear ImGui:
// - FAQ                  https://dearimgui.com/faq
// - Getting Started      https://dearimgui.com/getting-started
// - Documentation        https://dearimgui.com/docs (same as your local docs/ folder).
// - Introduction, links and more at the top of imgui.cpp

// FIXME: Multi-viewports is not yet functional in this example: backend and render code would set to set current context.

#define GL_SILENCE_DEPRECATION
#import <Cocoa/Cocoa.h>
#import <OpenGL/gl3.h>

#include "imgui.h"
#include "imgui_impl_opengl3.h"
#include "imgui_impl_osx.h"

//-----------------------------------------------------------------------------------
// AppView
//-----------------------------------------------------------------------------------

@interface AppView : NSOpenGLView
{
    NSTimer*    animationTimer;
}
@end

@implementation AppView

-(void)prepareOpenGL
{
    [super prepareOpenGL];

#ifndef DEBUG
    GLint swapInterval = 1;
    [[self openGLContext] setValues:&swapInterval forParameter:NSOpenGLContextParameterSwapInterval];
    if (swapInterval == 0)
        NSLog(@"Error: Cannot set swap interval.");
#endif
}

-(void)initialize
{
    // Setup Dear ImGui context
    // FIXME: This example doesn't have proper cleanup...
    IMGUI_CHECKVERSION();
    ImGui::CreateContext();
    ImGuiIO& io = ImGui::GetIO(); (void)io;
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows

    // Setup Dear ImGui style
    ImGuiStyle& style = ImGui::GetStyle();
    ImGui::StyleColorsDark();
    //ImGui::StyleColorsLight();
    //style.FontSizeBase = 16.0f;           // Default to 13.0f when unspecified, which allows crisp legacy font for non-4K screens.
    style.FrameRounding = 3.0f;
    style.GrabRounding = 3.0f;

    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
    {
        style.WindowRounding = 0.0f;
        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
    }

    // Setup Platform/Renderer backends
    [[self openGLContext] makeCurrentContext]; // ImGui_ImplOpenGL3_Init() requires a current GL context.
    ImGui_ImplOSX_Init(self);
    ImGui_ImplOpenGL3_Init();

    // Load Fonts
    // - If fonts are not explicitly loaded, Dear ImGui will select an embedded font: either AddFontDefaultVector() or AddFontDefaultBitmap().
    //   This selection is based on (style.FontSizeBase * style.FontScaleMain * style.FontScaleDpi) reaching a threshold.
    // - You can load multiple fonts and use ImGui::PushFont()/PopFont() to select them.
    // - If a file cannot be loaded, AddFont functions will return a nullptr. Please handle those errors in your code (e.g. use an assertion, display an error and quit).
    // - Read 'docs/FONTS.md' for more instructions and details.
    // - Use '#define IMGUI_ENABLE_FREETYPE' in your imconfig file to use FreeType for higher quality font rendering.
    // - 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->AddFontDefaultVector();
    //io.Fonts->AddFontDefaultBitmap();
    //io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\segoeui.ttf");
    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/DroidSans.ttf");
    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Roboto-Medium.ttf");
    //io.Fonts->AddFontFromFileTTF("../../misc/fonts/Cousine-Regular.ttf");
    //ImFont* font = io.Fonts->AddFontFromFileTTF("c:\\Windows\\Fonts\\ArialUni.ttf");
    //IM_ASSERT(font != nullptr);
}

-(void)updateAndDrawDemoView
{
    // Start the Dear ImGui frame
    ImGuiIO& io = ImGui::GetIO();
    ImGui_ImplOpenGL3_NewFrame();
    ImGui_ImplOSX_NewFrame(self);
    ImGui::NewFrame();

    // Our state (make them static = more or less global) as a convenience to keep the example terse.
    static bool show_demo_window = true;
    static bool show_another_window = false;
    static ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);

    // 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();
    ImDrawData* draw_data = ImGui::GetDrawData();

    [[self openGLContext] makeCurrentContext];
    GLsizei width  = (GLsizei)(draw_data->DisplaySize.x * draw_data->FramebufferScale.x + 0.5f);
    GLsizei height = (GLsizei)(draw_data->DisplaySize.y * draw_data->FramebufferScale.y + 0.5f);
    glViewport(0, 0, width, height);
    glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
    glClear(GL_COLOR_BUFFER_BIT);

    ImGui_ImplOpenGL3_RenderDrawData(draw_data);

    // Update and Render additional Platform Windows
    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
    {
        ImGui::UpdatePlatformWindows();
        ImGui::RenderPlatformWindowsDefault();
    }

    // Present
    [[self openGLContext] flushBuffer];

    if (!animationTimer)
        animationTimer = [NSTimer scheduledTimerWithTimeInterval:0.017 target:self selector:@selector(animationTimerFired:) userInfo:nil repeats:YES];
}

-(void)reshape                              { [super reshape]; [[self openGLContext] update]; [self updateAndDrawDemoView]; }
-(void)drawRect:(NSRect)bounds              { [self updateAndDrawDemoView]; }
-(void)animationTimerFired:(NSTimer*)timer  { [self setNeedsDisplay:YES]; }
-(void)dealloc                              { animationTimer = nil; }

@end

//-----------------------------------------------------------------------------------
// AppDelegate
//-----------------------------------------------------------------------------------

@interface AppDelegate : NSObject <NSApplicationDelegate>
@property (nonatomic, readonly) NSWindow* window;
@end

@implementation AppDelegate
@synthesize window = _window;

-(BOOL)applicationShouldTerminateAfterLastWindowClosed:(NSApplication *)theApplication
{
    return YES;
}

-(NSWindow*)window
{
    if (_window != nil)
        return _window;

    NSRect viewRect = NSMakeRect(100.0, 100.0, 100.0 + 1280.0, 100 + 800.0);

    _window = [[NSWindow alloc] initWithContentRect:viewRect styleMask:NSWindowStyleMaskTitled|NSWindowStyleMaskMiniaturizable|NSWindowStyleMaskResizable|NSWindowStyleMaskClosable backing:NSBackingStoreBuffered defer:YES];
    [_window setTitle:@"Dear ImGui OSX+OpenGL3 Example"];
    [_window setAcceptsMouseMovedEvents:YES];
    [_window setOpaque:YES];
    [_window makeKeyAndOrderFront:NSApp];

    return _window;
}

-(void)setupMenu
{
    NSMenu* mainMenuBar = [[NSMenu alloc] init];
    NSMenu* appMenu;
    NSMenuItem* menuItem;

    appMenu = [[NSMenu alloc] initWithTitle:@"Dear ImGui OSX+OpenGL3 Example"];
    menuItem = [appMenu addItemWithTitle:@"Quit Dear ImGui OSX+OpenGL3 Example" action:@selector(terminate:) keyEquivalent:@"q"];
    [menuItem setKeyEquivalentModifierMask:NSEventModifierFlagCommand];

    menuItem = [[NSMenuItem alloc] init];
    [menuItem setSubmenu:appMenu];

    [mainMenuBar addItem:menuItem];

    appMenu = nil;
    [NSApp setMainMenu:mainMenuBar];
}

-(void)dealloc
{
    _window = nil;
}

-(void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    // Make the application a foreground application (else it won't receive keyboard events)
    ProcessSerialNumber psn = {0, kCurrentProcess};
    TransformProcessType(&psn, kProcessTransformToForegroundApplication);

    // Menu
    [self setupMenu];

    NSOpenGLPixelFormatAttribute attrs[] =
    {
        NSOpenGLPFAOpenGLProfile, NSOpenGLProfileVersion3_2Core,
        NSOpenGLPFADoubleBuffer,
        NSOpenGLPFADepthSize, 32,
        0
    };

    NSOpenGLPixelFormat* format = [[NSOpenGLPixelFormat alloc] initWithAttributes:attrs];
    AppView* view = [[AppView alloc] initWithFrame:self.window.frame pixelFormat:format];
    format = nil;
#if MAC_OS_X_VERSION_MAX_ALLOWED >= 1070
    if (floor(NSAppKitVersionNumber) > NSAppKitVersionNumber10_6)
        [view setWantsBestResolutionOpenGLSurface:YES];
#endif // MAC_OS_X_VERSION_MAX_ALLOWED >= 1070
    [self.window setContentView:view];

    if ([view openGLContext] == nil)
        NSLog(@"No OpenGL Context!");

    [view initialize];
}

@end

//-----------------------------------------------------------------------------------
// Application main() function
//-----------------------------------------------------------------------------------

int main(int argc, const char* argv[])
{
    @autoreleasepool
    {
        NSApp = [NSApplication sharedApplication];
        AppDelegate* delegate = [[AppDelegate alloc] init];
        [[NSApplication sharedApplication] setDelegate:delegate];
        [NSApp run];
    }
    return NSApplicationMain(argc, argv);
}