Update example_emscripten_wgpu demo

Split emscripten only sections off
Added callbacks for getting device & adapter
Added multi viewport code
Added swapchain creation function
Added temporary canvas resize on creation until ocornut#6751 is merged in
(Refreshing will resize the canvas)

examples/example_emscripten_wgpu/main.cpp

@@ -0,0 +1,329 @@
+// Dear ImGui: standalone example application for Emscripten, using GLFW + WebGPU
+// (Emscripten is a C++-to-javascript compiler, used to publish executables for the web. See https://emscripten.org/)
+
+// 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
+
+#include "imgui.h"
+#include "imgui_impl_glfw.h"
+#include "imgui_impl_wgpu.h"
+#include <stdio.h>
+#ifdef __EMSCRIPTEN__
+#include <emscripten.h>
+#include <emscripten/html5.h>
+#include <emscripten/html5_webgpu.h>
+#else
+#include <webgpu/webgpu_glfw.h>
+#endif
+#include <GLFW/glfw3.h>
+#include <webgpu/webgpu.h>
+#include <webgpu/webgpu_cpp.h>
+
+// Global WebGPU required states
+static wgpu::Instance      wgpu_instance = nullptr;
+static wgpu::Surface       wgpu_surface = nullptr;
+static wgpu::Device        wgpu_device = nullptr;
+static WGPUTextureFormat   wgpu_preferred_fmt = WGPUTextureFormat_BGRA8Unorm;
+static WGPUSwapChain       wgpu_swap_chain = nullptr;
+static int                 wgpu_swap_chain_width = 1280;
+static int                 wgpu_swap_chain_height = 720;
+
+// Forward declarations
+static void MainLoopStep(void* window);
+static void InitWGPU(void (*callback)(wgpu::Device));
+static bool CreateWGPUSurface(GLFWwindow* window);
+static void CreateSwapChain(int width, int height);
+static void print_glfw_error(int error, const char* description);
+static void print_wgpu_error(WGPUErrorType error_type, const char* message, void*);
+static void RequestDeviceCallback(WGPURequestDeviceStatus status, WGPUDevice cDevice, const char* message, void* userdata);
+static void RequestAdapterCallback(WGPURequestAdapterStatus status, WGPUAdapter cAdapter,const char* message, void* userdata);
+// ------ Remove pending https://github.com/ocornut/imgui/pull/6751
+// glfwGetFramebufferSize not reporting changes in size
+#if defined(__EMSCRIPTEN__)
+EM_JS(int, canvas_get_width, (), {
+  return document.getElementById('canvas').width;
+});
+
+EM_JS(int, canvas_get_height, (), {
+  return document.getElementById('canvas').height;
+});
+#endif
+// -------------------------------
+
+// Main code
+int main(int, char**)
+{
+    InitWGPU([](wgpu::Device device) {
+        wgpu_device = device;
+
+        glfwSetErrorCallback(print_glfw_error);
+        if (!glfwInit())
+            exit(1);
+
+#if defined(__EMSCRIPTEN__)
+        wgpu_swap_chain_width = canvas_get_width();
+        wgpu_swap_chain_height = canvas_get_height();
+#endif
+        // Make sure GLFW does not initialize any graphics context.
+        // This needs to be done explicitly later.
+        glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
+        GLFWwindow* window = glfwCreateWindow(wgpu_swap_chain_width, wgpu_swap_chain_height, "Dear ImGui GLFW+WebGPU example", nullptr, nullptr);
+        if (!window)
+        {
+            glfwTerminate();
+            exit(1);
+        }
+
+        // Initialize the WebGPU surface
+        if (!CreateWGPUSurface(window))
+        {
+            if (window)
+                glfwDestroyWindow(window);
+            glfwTerminate();
+            exit(1);
+        }
+
+        glfwShowWindow(window);
+
+        // 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
+        io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multiviewport for docking branch 
+
+        // For an Emscripten build we are disabling file-system access, so let's not attempt to do a fopen() of the imgui.ini file.
+        // You may manually call LoadIniSettingsFromMemory() to load settings from your own storage.
+#if defined(__EMSCRIPTEN__)
+        io.IniFilename = nullptr;
+#endif
+
+        // Setup Dear ImGui style
+        ImGui::StyleColorsDark();
+        //ImGui::StyleColorsLight();
+
+        // Setup Platform/Renderer backends
+        ImGui_ImplGlfw_InitForOther(window, true);
+        ImGui_ImplWGPU_Init(wgpu_device.Get(), 3, wgpu_preferred_fmt, WGPUTextureFormat_Undefined, wgpu_instance.Get());
+
+        CreateSwapChain(wgpu_swap_chain_width, wgpu_swap_chain_height);
+
+        // 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 a nullptr. 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 \\ !
+        // - Emscripten allows preloading a file or folder to be accessible at runtime. See Makefile for details.
+        //io.Fonts->AddFontDefault();
+#ifndef IMGUI_DISABLE_FILE_FUNCTIONS
+        //io.Fonts->AddFontFromFileTTF("fonts/segoeui.ttf", 18.0f);
+        io.Fonts->AddFontFromFileTTF("fonts/DroidSans.ttf", 16.0f);
+        //io.Fonts->AddFontFromFileTTF("fonts/Roboto-Medium.ttf", 16.0f);
+        //io.Fonts->AddFontFromFileTTF("fonts/Cousine-Regular.ttf", 15.0f);
+        //io.Fonts->AddFontFromFileTTF("fonts/ProggyTiny.ttf", 10.0f);
+        //ImFont* font = io.Fonts->AddFontFromFileTTF("fonts/ArialUni.ttf", 18.0f, nullptr, io.Fonts->GetGlyphRangesJapanese());
+        //IM_ASSERT(font != nullptr);
+#endif
+
+        // This function will directly return and exit the main function.
+        // Make sure that no required objects get cleaned up.
+        // This way we can use the browsers 'requestAnimationFrame' to control the rendering.
+#if defined(__EMSCRIPTEN__)
+        emscripten_set_main_loop_arg(MainLoopStep, window, 0, false);
+#else
+        while (!glfwWindowShouldClose(window)) {
+            MainLoopStep(window);
+            wgpuSwapChainPresent(wgpu_swap_chain);
+            if (ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+            {
+                ImGui::UpdatePlatformWindows();
+                ImGui::RenderPlatformWindowsDefault();
+            }
+        }
+#endif
+    });
+
+    return 0;
+}
+
+static void RequestDeviceCallback(WGPURequestDeviceStatus status, WGPUDevice cDevice, const char* message, void* userdata)
+{
+    wgpu::Device device = wgpu::Device::Acquire(cDevice);
+    wgpuDeviceSetUncapturedErrorCallback(cDevice, print_wgpu_error, nullptr);
+    reinterpret_cast<void (*)(wgpu::Device)>(userdata)(device);
+}
+
+static void RequestAdapterCallback(WGPURequestAdapterStatus status, WGPUAdapter cAdapter, const char* message, void* userdata)
+{
+    if (status != WGPURequestAdapterStatus_Success) {
+        exit(0);
+    }
+
+    wgpu::Adapter adapter = wgpu::Adapter::Acquire(cAdapter);
+
+    adapter.RequestDevice(nullptr, RequestDeviceCallback, userdata);
+}
+
+static void InitWGPU(void (*callback)(wgpu::Device))
+{
+    wgpu_instance = wgpu::Instance::Acquire(wgpuCreateInstance(nullptr));
+    wgpu_instance.RequestAdapter(nullptr, RequestAdapterCallback, reinterpret_cast<void*>(callback));
+}
+
+static bool CreateWGPUSurface(GLFWwindow* window)
+{
+    // Use C++ wrapper due to misbehavior in Emscripten.
+    // Some offset computation for wgpuInstanceCreateSurface in JavaScript
+    // seem to be inline with struct alignments in the C++ structure
+#if defined(__EMSCRIPTEN__)
+    wgpu::SurfaceDescriptorFromCanvasHTMLSelector html_surface_desc = {};
+    html_surface_desc.selector = "#canvas";
+
+    wgpu::SurfaceDescriptor surfaceDesc = {};
+    surfaceDesc.nextInChain = &html_surface_desc;
+
+    wgpu_surface = wgpu_instance.CreateSurface(&surfaceDesc);
+#else
+    wgpu_surface = wgpu::glfw::CreateSurfaceForWindow(wgpu_instance, window);
+#endif
+
+    return wgpu_surface != nullptr;
+}
+
+static void CreateSwapChain(int width, int height)
+{
+    if (wgpu_swap_chain) {
+        wgpuSwapChainRelease(wgpu_swap_chain);
+        wgpu_swap_chain = nullptr;
+    }
+
+    wgpu_swap_chain_width = width;
+    wgpu_swap_chain_height = height;
+
+    WGPUSwapChainDescriptor swapDescriptor = {};
+    swapDescriptor.usage = WGPUTextureUsage_RenderAttachment;
+    swapDescriptor.format = wgpu_preferred_fmt;
+    swapDescriptor.width = wgpu_swap_chain_width;
+    swapDescriptor.height = wgpu_swap_chain_height;
+    swapDescriptor.presentMode = WGPUPresentMode_Fifo;
+
+    wgpu_swap_chain = wgpuDeviceCreateSwapChain(wgpu_device.Get(), wgpu_surface.Get(), &swapDescriptor);
+}
+
+static void MainLoopStep(void* window)
+{
+    ImGuiIO& io = ImGui::GetIO();
+
+    glfwPollEvents();
+
+    int width, height;
+    glfwGetFramebufferSize((GLFWwindow*)window, &width, &height);
+
+    // React to changes in screen size
+    if (width != wgpu_swap_chain_width && height != wgpu_swap_chain_height)
+    {
+        ImGui_ImplWGPU_InvalidateDeviceObjects();
+        CreateSwapChain(width, height);
+        ImGui_ImplWGPU_CreateDeviceObjects();
+    }
+
+    // Start the Dear ImGui frame
+    ImGui_ImplWGPU_NewFrame();
+    ImGui_ImplGlfw_NewFrame();
+    ImGui::NewFrame();
+
+    // Our state
+    // (we use static, which essentially makes the variable globals, as a convenience to keep the example code easy to follow)
+    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();
+
+    WGPURenderPassColorAttachment color_attachments = {};
+    color_attachments.loadOp = WGPULoadOp_Clear;
+    color_attachments.storeOp = WGPUStoreOp_Store;
+    color_attachments.clearValue = { clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w };
+    color_attachments.view = wgpuSwapChainGetCurrentTextureView(wgpu_swap_chain);
+
+    WGPURenderPassDescriptor render_pass_desc = {};
+    render_pass_desc.colorAttachmentCount = 1;
+    render_pass_desc.colorAttachments = &color_attachments;
+    render_pass_desc.depthStencilAttachment = nullptr;
+
+    WGPUCommandEncoderDescriptor enc_desc = {};
+    WGPUCommandEncoder encoder = wgpuDeviceCreateCommandEncoder(wgpu_device.Get(), &enc_desc);
+
+    WGPURenderPassEncoder pass = wgpuCommandEncoderBeginRenderPass(encoder, &render_pass_desc);
+    ImGui_ImplWGPU_RenderDrawData(ImGui::GetDrawData(), pass);
+    wgpuRenderPassEncoderEnd(pass);
+
+    WGPUCommandBufferDescriptor cmd_buffer_desc = {};
+    WGPUCommandBuffer cmd_buffer = wgpuCommandEncoderFinish(encoder, &cmd_buffer_desc);
+    WGPUQueue queue = wgpuDeviceGetQueue(wgpu_device.Get());
+    wgpuQueueSubmit(queue, 1, &cmd_buffer);
+}
+
+static void print_glfw_error(int error, const char* description)
+{
+    printf("GLFW Error %d: %s\n", error, description);
+}
+
+static void print_wgpu_error(WGPUErrorType error_type, const char* message, void*)
+{
+    const char* error_type_lbl = "";
+    switch (error_type)
+    {
+    case WGPUErrorType_Validation:  error_type_lbl = "Validation"; break;
+    case WGPUErrorType_OutOfMemory: error_type_lbl = "Out of memory"; break;
+    case WGPUErrorType_Unknown:     error_type_lbl = "Unknown"; break;
+    case WGPUErrorType_DeviceLost:  error_type_lbl = "Device lost"; break;
+    default:                        error_type_lbl = "Unknown";
+    }
+    printf("%s error: %s\n", error_type_lbl, message);
+}

examples/example_glfw_wgpu/web/index.html

@@ -73,6 +73,11 @@
       }
 
       {
+        // ------ Remove once https://github.com/ocornut/imgui/pull/6751 is merged in
+        let canvas = document.getElementById('canvas');
+          canvas.width = window.innerWidth;
+          canvas.height = window.innerHeight;
+        // ------ 
           const js = document.createElement('script');
           js.async = true;
           js.src = "index.js";