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Examples: Emscripten+WebGPU: slightly refactor like other Emscripten …
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…compatible Desktop examples, as aiming to make this suppot desktop eventually.

Also aimed at reducing diff for #7132 tho this will lead in conflict.
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@ocornut
ocornut committed Jan 22, 2024
1 parent 1590850 commit e3c7ff9
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0 examples/example_emscripten_wgpu/Makefile → ...ample_emscripten_wgpu/Makefile.emscripten
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2 changes: 1 addition & 1 deletion examples/example_emscripten_wgpu/README.md
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Expand Up @@ -6,7 +6,7 @@

- You may also refer to our [Continuous Integration setup](https://github.com/ocornut/imgui/tree/master/.github/workflows) for Emscripten setup.

- Then build using `make` while in the `example_emscripten_wgpu/` directory.
- Then build using `make -f Makefile.emscripten` while in the `example_emscripten_wgpu/` directory.

- Requires recent Emscripten as WGPU is still a work-in-progress API.

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289 changes: 155 additions & 134 deletions examples/example_emscripten_wgpu/main.cpp
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Expand Up @@ -11,13 +11,20 @@
#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>
#endif
#include <GLFW/glfw3.h>
#include <webgpu/webgpu.h>
#include <webgpu/webgpu_cpp.h>

// This example can also compile and run with Emscripten! See 'Makefile.emscripten' for details.
#ifdef __EMSCRIPTEN__
#include "../libs/emscripten/emscripten_mainloop_stub.h"
#endif

// Global WebGPU required states
static WGPUDevice wgpu_device = nullptr;
static WGPUSurface wgpu_surface = nullptr;
Expand All @@ -27,27 +34,41 @@ static int wgpu_swap_chain_width = 0;
static int wgpu_swap_chain_height = 0;

// Forward declarations
static void MainLoopStep(void* window);
static bool InitWGPU();
static void print_glfw_error(int error, const char* description);
static void print_wgpu_error(WGPUErrorType error_type, const char* message, void*);
static void CreateSwapChain(int width, int height);

static void glfw_error_callback(int error, const char* description)
{
printf("GLFW Error %d: %s\n", error, description);
}

static void wgpu_error_callback(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);
}

// Main code
int main(int, char**)
{
glfwSetErrorCallback(print_glfw_error);
glfwSetErrorCallback(glfw_error_callback);
if (!glfwInit())
return 1;

// 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(1280, 720, "Dear ImGui GLFW+WebGPU example", nullptr, nullptr);
if (!window)
{
glfwTerminate();
if (window == nullptr)
return 1;
}

// Initialize the WebGPU environment
if (!InitWGPU())
Expand All @@ -66,17 +87,15 @@ int main(int, char**)
io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard; // Enable Keyboard Controls
io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad; // Enable Gamepad Controls

// 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.
io.IniFilename = nullptr;

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

// Setup Platform/Renderer backends
ImGui_ImplGlfw_InitForOther(window, true);
#ifdef __EMSCRIPTEN__
ImGui_ImplGlfw_InstallEmscriptenCanvasResizeCallback("#canvas");
#endif
ImGui_ImplWGPU_Init(wgpu_device, 3, wgpu_preferred_fmt, WGPUTextureFormat_Undefined);

// Load Fonts
Expand All @@ -99,10 +118,117 @@ int main(int, char**)
//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.
emscripten_set_main_loop_arg(MainLoopStep, window, 0, false);
// 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
#ifdef __EMSCRIPTEN__
// 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.
io.IniFilename = nullptr;
EMSCRIPTEN_MAINLOOP_BEGIN
#else
while (!glfwWindowShouldClose(window))
#endif
{
// 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, 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.
glfwPollEvents();

// React to changes in screen size
int width, height;
glfwGetFramebufferSize((GLFWwindow*)window, &width, &height);
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();

// 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, &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);
wgpuQueueSubmit(queue, 1, &cmd_buffer);
}
#ifdef __EMSCRIPTEN__
EMSCRIPTEN_MAINLOOP_END;
#endif

// Cleanup
ImGui_ImplWGPU_Shutdown();
ImGui_ImplGlfw_Shutdown();
ImGui::DestroyContext();

glfwDestroyWindow(window);
glfwTerminate();

return 0;
}
Expand All @@ -113,7 +239,7 @@ static bool InitWGPU()
if (!wgpu_device)
return false;

wgpuDeviceSetUncapturedErrorCallback(wgpu_device, print_wgpu_error, nullptr);
wgpuDeviceSetUncapturedErrorCallback(wgpu_device, wgpu_error_callback, nullptr);

// Use C++ wrapper due to misbehavior in Emscripten.
// Some offset computation for wgpuInstanceCreateSurface in JavaScript
Expand All @@ -133,122 +259,17 @@ static bool InitWGPU()
return true;
}

static void MainLoopStep(void* window)
static void CreateSwapChain(int width, int height)
{
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();
if (wgpu_swap_chain)
wgpuSwapChainRelease(wgpu_swap_chain);
wgpu_swap_chain_width = width;
wgpu_swap_chain_height = height;
WGPUSwapChainDescriptor swap_chain_desc = {};
swap_chain_desc.usage = WGPUTextureUsage_RenderAttachment;
swap_chain_desc.format = wgpu_preferred_fmt;
swap_chain_desc.width = width;
swap_chain_desc.height = height;
swap_chain_desc.presentMode = WGPUPresentMode_Fifo;
wgpu_swap_chain = wgpuDeviceCreateSwapChain(wgpu_device, wgpu_surface, &swap_chain_desc);
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, &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);
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);
if (wgpu_swap_chain)
wgpuSwapChainRelease(wgpu_swap_chain);
wgpu_swap_chain_width = width;
wgpu_swap_chain_height = height;
WGPUSwapChainDescriptor swap_chain_desc = {};
swap_chain_desc.usage = WGPUTextureUsage_RenderAttachment;
swap_chain_desc.format = wgpu_preferred_fmt;
swap_chain_desc.width = width;
swap_chain_desc.height = height;
swap_chain_desc.presentMode = WGPUPresentMode_Fifo;
wgpu_swap_chain = wgpuDeviceCreateSwapChain(wgpu_device, wgpu_surface, &swap_chain_desc);
}

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