NYXGFX/examples/imgui/imgui.zig

//! ----------------------------------------------------
//! SDL3 + Vulkan
//!
//! Used dear_bindings with docking imgui branch
//! https://mrscriptx.github.io/devlog/zig/2025/04/30/zig-linking-dear-imgui.html
//! ----------------------------------------------------

const im = @import("imgui");
const im_vk = @import("imgui_impl_vulkan");
const im_sdl = @import("imgui_impl_sdl3");

const std = @import("std");
const sdl = @import("sdl");
const Gfx = @import("gfx");

pub fn main(init: std.process.Init) !void {

    //
    // SDL
    //

    // --- # ---
    if (!sdl.SDL_Init(sdl.SDL_INIT_VIDEO)) return error.FailedToInitSDL;
    defer sdl.SDL_Quit();

    // --- # ---
    const window = sdl.SDL_CreateWindow("NYXGFX", 800, 600, sdl.SDL_WINDOW_VULKAN) orelse return error.FailedTomakeWindow;
    defer sdl.SDL_DestroyWindow(window);

    // --- # ---
    const props = sdl.SDL_GetWindowProperties(window);
    const display = sdl.SDL_GetPointerProperty(props, sdl.SDL_PROP_WINDOW_X11_DISPLAY_POINTER, null);
    const xwindow = sdl.SDL_GetNumberProperty(props, sdl.SDL_PROP_WINDOW_X11_WINDOW_NUMBER, 0);

    //
    // GFX
    //

    // --- # ---
    var gfx: Gfx = try .init(
        init.gpa,
        init.io,
    );
    defer gfx.deinit();

    // --- # ---
    const instance = try gfx.makeInstance(.{
        .vulkan = .{
            .api_version = .v1_3,
        },
    });

    const surface = try gfx.makeSurface(.{
        .xlib = .{
            .window = @intCast(xwindow),
            .display = display.?,
        },
    }, instance);

    const adapter = try gfx.makeAdapter(.{}, instance);
    const device = try gfx.makeDevice(adapter, surface);
    const swapchain = try gfx.makeSwapchain(adapter, device, surface);

    //
    // IMGUI
    //

    // --- CREATE IMGUI CTX ---
    const ctx = im.ImGui_CreateContext(null) orelse return error.FailedToCreateImGuiContext;
    defer im.ImGui_DestroyContext(ctx);

    // --- INIT IMGUI FOR SDL3 + VK ---
    if (!im_sdl.cImGui_ImplSDL3_InitForVulkan(@ptrCast(window))) return error.FailedToImplImGuiForSDL;
    defer im_sdl.cImGui_ImplSDL3_Shutdown();

    // --- SET IO ---
    const io = im.ImGui_GetIO() orelse return error.FailedToGetImGuiIO;
    io.*.ConfigFlags |= im.ImGuiConfigFlags_NavEnableKeyboard;
    io.*.ConfigFlags |= im.ImGuiConfigFlags_DockingEnable;

    // --- GET VK RAW DEVICE ---
    const raw_device = switch (try gfx.getRawDevice(device)) {
        .vulkan => |v| v,
    };

    // --- GET VK RAW SWAPCHAIN ---
    const raw_swapchain = try gfx.getRawSwapchain(swapchain);

    // --- INIT IMGUI FOR VK ---
    var color_format: im_vk.VkFormat = raw_swapchain.format;
    var im_info: im_vk.ImGui_ImplVulkan_InitInfo = .{
        .Instance = @ptrCast((try gfx.getRawInstance(instance)).vulkan),
        .PhysicalDevice = blk: {
            switch (try gfx.getRawAdapter(adapter)) {
                .vulkan => |v| break :blk @ptrCast(v),
            }
        },
        .Device = @ptrCast(raw_device.device),
        .Queue = @ptrCast(raw_device.present_queue),
        .DescriptorPoolSize = 1024,
        .MinImageCount = 2,
        .ImageCount = @intCast(raw_swapchain.images.len),
        .PipelineInfoMain = .{
            .MSAASamples = im_vk.VK_SAMPLE_COUNT_1_BIT,
            .PipelineRenderingCreateInfo = .{
                .sType = im_vk.VK_STRUCTURE_TYPE_PIPELINE_RENDERING_CREATE_INFO_KHR,
                .colorAttachmentCount = 1,
                .pColorAttachmentFormats = &color_format,
            },
        },

        .UseDynamicRendering = true, // <--- vulkan implementation specific
    };
    if (!im_vk.cImGui_ImplVulkan_Init(&im_info)) return error.FailedToImplImGuiForVulkan;
    defer {
        _ = im_vk.vkDeviceWaitIdle(@ptrCast(raw_device.device));
        im_vk.cImGui_ImplVulkan_Shutdown();
    }

    //
    // MAIN LOOP
    //

    // --- MISC ---
    var event: sdl.SDL_Event = undefined;
    var running: bool = true;

    while (running) {
        // --- INPUTS ---
        while (sdl.SDL_PollEvent(&event)) {
            switch (event.type) {
                sdl.SDL_EVENT_QUIT => running = false,
                else => {},
            }
            _ = im_sdl.cImGui_ImplSDL3_ProcessEvent(@ptrCast(&event));
        }

        { // IMGUI
            // --- NEW IMGUI FRAME ---
            im_sdl.cImGui_ImplSDL3_NewFrame();
            im_vk.cImGui_ImplVulkan_NewFrame();
            im.ImGui_NewFrame();

            // --- UI ---
            if (im.ImGui_Begin("Inspector", null, 0)) {
                defer im.ImGui_End();

                im.ImGui_Text("Hello World");
                if (im.ImGui_Button("Click Me")) {}
            }

            // --- DEMO ---
            im.ImGui_ShowDemoWindow(null);

            // --- RENDER IMGUI ---
            im.ImGui_Render();
        }

        // --- FRAME ---
        try gfx.beginFrame(swapchain, device);
        defer gfx.endFrame(swapchain, device) catch unreachable;

        // --- NEW PASS ---
        if (gfx.beginPass(swapchain, .{
            .clear_color = .{ 0.01, 0.01, 0.01, 1.0 },
        })) |pass| {
            defer pass.end();

            // --- RENDER IMGUI ---
            switch (try gfx.getRawFrame()) {
                .vulkan => |v| {
                    const draw_data = im.ImGui_GetDrawData() orelse return;

                    im_vk.cImGui_ImplVulkan_RenderDrawData(
                        @ptrCast(draw_data),
                        @ptrCast(v.cmd_buf),
                    );
                },
            }
        }
    }
}