Backends, Examples: Added support for WebGPU and corresponding example (#3632)

(Squashed 11 commits)

.github/workflows/build.yml

@@ -400,6 +400,13 @@ jobs:
         popd
         make -C examples/example_emscripten_opengl3
 
+    - name: Build example_emscripten_wgpu
+      run: |
+        pushd emsdk-master
+        source ./emsdk_env.sh
+        popd
+        make -C examples/example_emscripten_wgpu
+
   Discord-CI:
     runs-on: ubuntu-18.04
     if: always()

backends/imgui_impl_wgpu.cpp

@@ -0,0 +1,783 @@
+// dear imgui: Renderer for WebGPU
+// This needs to be used along with a Platform Binding (e.g. GLFW)
+
+// Implemented features:
+//  [X] Renderer: User texture binding. Use 'WGPUTextureView' as ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
+
+// You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
+// 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
+
+// CHANGELOG
+// (minor and older changes stripped away, please see git history for details)
+
+#include "imgui.h"
+#include "imgui_impl_wgpu.h"
+
+// CRT
+#include <limits.h>
+
+// WebGPU
+#include <webgpu/webgpu.h>
+
+// ImGui prototypes
+ImGuiID ImHashData(const void* data_p, size_t data_size, ImU32 seed = 0);
+
+// WebGPU data
+static WGPUDevice                      g_wgpuDevice = NULL;
+static WGPUTextureFormat               g_renderTargetFormat = WGPUTextureFormat_Undefined;
+static WGPURenderPipeline              g_pipelineState = NULL;
+
+struct RenderResources
+{
+    // Font texture
+    WGPUTexture FontTexture;
+
+    // Texture view for font texture
+    WGPUTextureView FontTextureView;
+
+    // Sampler for the font texture
+    WGPUSampler Sampler;
+
+    // Shader uniforms
+    WGPUBuffer Uniforms;
+
+    // Resources bind-group to bind the common resources to pipeline
+    WGPUBindGroup CommonBindGroup;
+
+    // Bind group layout for image textures
+    WGPUBindGroupLayout ImageBindGroupLayout;
+
+    // Resources bind-group to bind the font/image resources to pipeline
+    ImGuiStorage ImageBindGroups;
+
+    // Default font-resource of ImGui
+    WGPUBindGroup ImageBindGroup;
+};
+static RenderResources g_resources;
+
+struct FrameResources
+{
+    WGPUBuffer  IndexBuffer;
+    WGPUBuffer  VertexBuffer;
+    ImDrawIdx*  IndexBufferHost;
+    ImDrawVert* VertexBufferHost;
+    int         IndexBufferSize;
+    int         VertexBufferSize;
+};
+static FrameResources*  g_pFrameResources = NULL;
+static unsigned int     g_numFramesInFlight = 0;
+static unsigned int     g_frameIndex = UINT_MAX;
+
+struct Uniforms
+{
+    float MVP[4][4];
+};
+
+//-----------------------------------------------------------------------------
+// SHADERS
+//-----------------------------------------------------------------------------
+
+// glsl_shader.vert, compiled with:
+// # glslangValidator -V -x -o glsl_shader.vert.u32 glsl_shader.vert
+/*
+#version 450 core
+layout(location = 0) in vec2 aPos;
+layout(location = 1) in vec2 aUV;
+layout(location = 2) in vec4 aColor;
+layout(set=0, binding = 0) uniform transform { mat4 mvp; };
+
+out gl_PerVertex { vec4 gl_Position; };
+layout(location = 0) out struct { vec4 Color; vec2 UV; } Out;
+
+void main()
+{
+    Out.Color = aColor;
+    Out.UV = aUV;
+    gl_Position = mvp * vec4(aPos, 0, 1);
+}
+*/
+static uint32_t __glsl_shader_vert_spv[] =
+{
+    0x07230203,0x00010000,0x00080007,0x0000002c,0x00000000,0x00020011,0x00000001,0x0006000b,
+    0x00000001,0x4c534c47,0x6474732e,0x3035342e,0x00000000,0x0003000e,0x00000000,0x00000001,
+    0x000a000f,0x00000000,0x00000004,0x6e69616d,0x00000000,0x0000000b,0x0000000f,0x00000015,
+    0x0000001b,0x00000023,0x00030003,0x00000002,0x000001c2,0x00040005,0x00000004,0x6e69616d,
+    0x00000000,0x00030005,0x00000009,0x00000000,0x00050006,0x00000009,0x00000000,0x6f6c6f43,
+    0x00000072,0x00040006,0x00000009,0x00000001,0x00005655,0x00030005,0x0000000b,0x0074754f,
+    0x00040005,0x0000000f,0x6c6f4361,0x0000726f,0x00030005,0x00000015,0x00565561,0x00060005,
+    0x00000019,0x505f6c67,0x65567265,0x78657472,0x00000000,0x00060006,0x00000019,0x00000000,
+    0x505f6c67,0x7469736f,0x006e6f69,0x00030005,0x0000001b,0x00000000,0x00050005,0x0000001d,
+    0x6e617274,0x726f6673,0x0000006d,0x00040006,0x0000001d,0x00000000,0x0070766d,0x00030005,
+    0x0000001f,0x00000000,0x00040005,0x00000023,0x736f5061,0x00000000,0x00040047,0x0000000b,
+    0x0000001e,0x00000000,0x00040047,0x0000000f,0x0000001e,0x00000002,0x00040047,0x00000015,
+    0x0000001e,0x00000001,0x00050048,0x00000019,0x00000000,0x0000000b,0x00000000,0x00030047,
+    0x00000019,0x00000002,0x00040048,0x0000001d,0x00000000,0x00000005,0x00050048,0x0000001d,
+    0x00000000,0x00000023,0x00000000,0x00050048,0x0000001d,0x00000000,0x00000007,0x00000010,
+    0x00030047,0x0000001d,0x00000002,0x00040047,0x0000001f,0x00000022,0x00000000,0x00040047,
+    0x0000001f,0x00000021,0x00000000,0x00040047,0x00000023,0x0000001e,0x00000000,0x00020013,
+    0x00000002,0x00030021,0x00000003,0x00000002,0x00030016,0x00000006,0x00000020,0x00040017,
+    0x00000007,0x00000006,0x00000004,0x00040017,0x00000008,0x00000006,0x00000002,0x0004001e,
+    0x00000009,0x00000007,0x00000008,0x00040020,0x0000000a,0x00000003,0x00000009,0x0004003b,
+    0x0000000a,0x0000000b,0x00000003,0x00040015,0x0000000c,0x00000020,0x00000001,0x0004002b,
+    0x0000000c,0x0000000d,0x00000000,0x00040020,0x0000000e,0x00000001,0x00000007,0x0004003b,
+    0x0000000e,0x0000000f,0x00000001,0x00040020,0x00000011,0x00000003,0x00000007,0x0004002b,
+    0x0000000c,0x00000013,0x00000001,0x00040020,0x00000014,0x00000001,0x00000008,0x0004003b,
+    0x00000014,0x00000015,0x00000001,0x00040020,0x00000017,0x00000003,0x00000008,0x0003001e,
+    0x00000019,0x00000007,0x00040020,0x0000001a,0x00000003,0x00000019,0x0004003b,0x0000001a,
+    0x0000001b,0x00000003,0x00040018,0x0000001c,0x00000007,0x00000004,0x0003001e,0x0000001d,
+    0x0000001c,0x00040020,0x0000001e,0x00000002,0x0000001d,0x0004003b,0x0000001e,0x0000001f,
+    0x00000002,0x00040020,0x00000020,0x00000002,0x0000001c,0x0004003b,0x00000014,0x00000023,
+    0x00000001,0x0004002b,0x00000006,0x00000025,0x00000000,0x0004002b,0x00000006,0x00000026,
+    0x3f800000,0x00050036,0x00000002,0x00000004,0x00000000,0x00000003,0x000200f8,0x00000005,
+    0x0004003d,0x00000007,0x00000010,0x0000000f,0x00050041,0x00000011,0x00000012,0x0000000b,
+    0x0000000d,0x0003003e,0x00000012,0x00000010,0x0004003d,0x00000008,0x00000016,0x00000015,
+    0x00050041,0x00000017,0x00000018,0x0000000b,0x00000013,0x0003003e,0x00000018,0x00000016,
+    0x00050041,0x00000020,0x00000021,0x0000001f,0x0000000d,0x0004003d,0x0000001c,0x00000022,
+    0x00000021,0x0004003d,0x00000008,0x00000024,0x00000023,0x00050051,0x00000006,0x00000027,
+    0x00000024,0x00000000,0x00050051,0x00000006,0x00000028,0x00000024,0x00000001,0x00070050,
+    0x00000007,0x00000029,0x00000027,0x00000028,0x00000025,0x00000026,0x00050091,0x00000007,
+    0x0000002a,0x00000022,0x00000029,0x00050041,0x00000011,0x0000002b,0x0000001b,0x0000000d,
+    0x0003003e,0x0000002b,0x0000002a,0x000100fd,0x00010038
+};
+
+// glsl_shader.frag, compiled with:
+// # glslangValidator -V -x -o glsl_shader.frag.u32 glsl_shader.frag
+/*
+#version 450 core
+layout(location = 0) out vec4 fColor;
+layout(set=0, binding=1) uniform sampler s;
+layout(set=1, binding=0) uniform texture2D t;
+layout(location = 0) in struct { vec4 Color; vec2 UV; } In;
+void main()
+{
+    fColor = In.Color * texture(sampler2D(t, s), In.UV.st);
+}
+*/
+static uint32_t __glsl_shader_frag_spv[] =
+{
+    0x07230203,0x00010000,0x00080007,0x00000023,0x00000000,0x00020011,0x00000001,0x0006000b,
+    0x00000001,0x4c534c47,0x6474732e,0x3035342e,0x00000000,0x0003000e,0x00000000,0x00000001,
+    0x0007000f,0x00000004,0x00000004,0x6e69616d,0x00000000,0x00000009,0x0000000d,0x00030010,
+    0x00000004,0x00000007,0x00030003,0x00000002,0x000001c2,0x00040005,0x00000004,0x6e69616d,
+    0x00000000,0x00040005,0x00000009,0x6c6f4366,0x0000726f,0x00030005,0x0000000b,0x00000000,
+    0x00050006,0x0000000b,0x00000000,0x6f6c6f43,0x00000072,0x00040006,0x0000000b,0x00000001,
+    0x00005655,0x00030005,0x0000000d,0x00006e49,0x00030005,0x00000015,0x00000074,0x00030005,
+    0x00000019,0x00000073,0x00040047,0x00000009,0x0000001e,0x00000000,0x00040047,0x0000000d,
+    0x0000001e,0x00000000,0x00040047,0x00000015,0x00000022,0x00000001,0x00040047,0x00000015,
+    0x00000021,0x00000000,0x00040047,0x00000019,0x00000022,0x00000000,0x00040047,0x00000019,
+    0x00000021,0x00000001,0x00020013,0x00000002,0x00030021,0x00000003,0x00000002,0x00030016,
+    0x00000006,0x00000020,0x00040017,0x00000007,0x00000006,0x00000004,0x00040020,0x00000008,
+    0x00000003,0x00000007,0x0004003b,0x00000008,0x00000009,0x00000003,0x00040017,0x0000000a,
+    0x00000006,0x00000002,0x0004001e,0x0000000b,0x00000007,0x0000000a,0x00040020,0x0000000c,
+    0x00000001,0x0000000b,0x0004003b,0x0000000c,0x0000000d,0x00000001,0x00040015,0x0000000e,
+    0x00000020,0x00000001,0x0004002b,0x0000000e,0x0000000f,0x00000000,0x00040020,0x00000010,
+    0x00000001,0x00000007,0x00090019,0x00000013,0x00000006,0x00000001,0x00000000,0x00000000,
+    0x00000000,0x00000001,0x00000000,0x00040020,0x00000014,0x00000000,0x00000013,0x0004003b,
+    0x00000014,0x00000015,0x00000000,0x0002001a,0x00000017,0x00040020,0x00000018,0x00000000,
+    0x00000017,0x0004003b,0x00000018,0x00000019,0x00000000,0x0003001b,0x0000001b,0x00000013,
+    0x0004002b,0x0000000e,0x0000001d,0x00000001,0x00040020,0x0000001e,0x00000001,0x0000000a,
+    0x00050036,0x00000002,0x00000004,0x00000000,0x00000003,0x000200f8,0x00000005,0x00050041,
+    0x00000010,0x00000011,0x0000000d,0x0000000f,0x0004003d,0x00000007,0x00000012,0x00000011,
+    0x0004003d,0x00000013,0x00000016,0x00000015,0x0004003d,0x00000017,0x0000001a,0x00000019,
+    0x00050056,0x0000001b,0x0000001c,0x00000016,0x0000001a,0x00050041,0x0000001e,0x0000001f,
+    0x0000000d,0x0000001d,0x0004003d,0x0000000a,0x00000020,0x0000001f,0x00050057,0x00000007,
+    0x00000021,0x0000001c,0x00000020,0x00050085,0x00000007,0x00000022,0x00000012,0x00000021,
+    0x0003003e,0x00000009,0x00000022,0x000100fd,0x00010038
+};
+
+static void SafeRelease(ImDrawIdx*& res)
+{
+    if (res)
+        delete[] res;
+    res = NULL;
+}
+static void SafeRelease(ImDrawVert*& res)
+{
+    if (res)
+        delete[] res;
+    res = NULL;
+}
+static void SafeRelease(WGPUBindGroupLayout& res)
+{
+    if (res)
+        wgpuBindGroupLayoutRelease(res);
+    res = NULL;
+}
+static void SafeRelease(WGPUBindGroup& res)
+{
+    if (res)
+        wgpuBindGroupRelease(res);
+    res = NULL;
+}
+static void SafeRelease(WGPUBuffer& res)
+{
+    if (res)
+        wgpuBufferRelease(res);
+    res = NULL;
+}
+static void SafeRelease(WGPURenderPipeline& res)
+{
+    if (res)
+        wgpuRenderPipelineRelease(res);
+    res = NULL;
+}
+static void SafeRelease(WGPUSampler& res)
+{
+    if (res)
+        wgpuSamplerRelease(res);
+    res = NULL;
+}
+static void SafeRelease(WGPUShaderModule& res)
+{
+    if (res)
+        wgpuShaderModuleRelease(res);
+    res = NULL;
+}
+static void SafeRelease(WGPUTextureView& res)
+{
+    if (res)
+        wgpuTextureViewRelease(res);
+    res = NULL;
+}
+static void SafeRelease(WGPUTexture& res)
+{
+    if (res)
+        wgpuTextureRelease(res);
+    res = NULL;
+}
+
+static void SafeRelease(RenderResources& res)
+{
+    SafeRelease(res.FontTexture);
+    SafeRelease(res.FontTextureView);
+    SafeRelease(res.Sampler);
+    SafeRelease(res.Uniforms);
+    SafeRelease(res.CommonBindGroup);
+    SafeRelease(res.ImageBindGroupLayout);
+    SafeRelease(res.ImageBindGroup);
+};
+
+static void SafeRelease(FrameResources& res)
+{
+    SafeRelease(res.IndexBuffer);
+    SafeRelease(res.VertexBuffer);
+    SafeRelease(res.IndexBufferHost);
+    SafeRelease(res.VertexBufferHost);
+}
+
+static WGPUProgrammableStageDescriptor ImGui_ImplWGPU_CreateShaderModule(uint32_t* binary_data, uint32_t binary_data_size)
+{
+    WGPUShaderModuleSPIRVDescriptor spirv_desc = {};
+    spirv_desc.chain.sType = WGPUSType_ShaderModuleSPIRVDescriptor;
+    spirv_desc.codeSize = binary_data_size;
+    spirv_desc.code = binary_data;
+
+    WGPUShaderModuleDescriptor desc;
+    desc.nextInChain = reinterpret_cast<WGPUChainedStruct*>(&spirv_desc);
+
+    WGPUProgrammableStageDescriptor stage_desc = {};
+    stage_desc.module = wgpuDeviceCreateShaderModule(g_wgpuDevice, &desc);
+    stage_desc.entryPoint = "main";
+    return stage_desc;
+}
+
+static WGPUBindGroup ImGui_ImplWGPU_CreateImageBindGroup(WGPUBindGroupLayout layout, WGPUTextureView texture)
+{
+    WGPUBindGroupEntry image_bg_entries[] = {
+        { 0, 0, 0, 0, 0, texture },
+    };
+
+    WGPUBindGroupDescriptor image_bg_descriptor = {};
+    image_bg_descriptor.layout = layout;
+    image_bg_descriptor.entryCount = sizeof(image_bg_entries) / sizeof(WGPUBindGroupEntry);
+    image_bg_descriptor.entries = image_bg_entries;
+    return wgpuDeviceCreateBindGroup(g_wgpuDevice, &image_bg_descriptor);
+}
+
+static void ImGui_ImplWGPU_SetupRenderState(ImDrawData* draw_data, WGPURenderPassEncoder ctx, FrameResources* fr)
+{
+    // Setup orthographic projection matrix into our constant buffer
+    // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right).
+    {
+        float L = draw_data->DisplayPos.x;
+        float R = draw_data->DisplayPos.x + draw_data->DisplaySize.x;
+        float T = draw_data->DisplayPos.y;
+        float B = draw_data->DisplayPos.y + draw_data->DisplaySize.y;
+        float mvp[4][4] =
+        {
+            { 2.0f/(R-L),   0.0f,           0.0f,       0.0f },
+            { 0.0f,         2.0f/(T-B),     0.0f,       0.0f },
+            { 0.0f,         0.0f,           0.5f,       0.0f },
+            { (R+L)/(L-R),  (T+B)/(B-T),    0.5f,       1.0f },
+        };
+        wgpuQueueWriteBuffer(wgpuDeviceGetDefaultQueue(g_wgpuDevice), g_resources.Uniforms, 0, mvp, sizeof(mvp));
+    }
+
+    // Setup viewport
+    wgpuRenderPassEncoderSetViewport(ctx, 0, 0, draw_data->DisplaySize.x, draw_data->DisplaySize.y, 0, 1);
+
+    // Bind shader and vertex buffers
+    unsigned int stride = sizeof(ImDrawVert);
+    unsigned int offset = 0;
+    wgpuRenderPassEncoderSetVertexBuffer(ctx, 0, fr->VertexBuffer, offset, fr->VertexBufferSize * stride);
+    wgpuRenderPassEncoderSetIndexBuffer(ctx, fr->IndexBuffer, sizeof(ImDrawIdx) == 2 ? WGPUIndexFormat_Uint16 : WGPUIndexFormat_Uint32, 0, fr->IndexBufferSize * sizeof(ImDrawIdx));
+    wgpuRenderPassEncoderSetPipeline(ctx, g_pipelineState);
+    wgpuRenderPassEncoderSetBindGroup(ctx, 0, g_resources.CommonBindGroup, 0, NULL);
+
+    // Setup blend factor
+    WGPUColor blend_color = { 0.f, 0.f, 0.f, 0.f };
+    wgpuRenderPassEncoderSetBlendColor(ctx, &blend_color);
+}
+
+// Render function
+// (this used to be set in io.RenderDrawListsFn and called by ImGui::Render(), but you can now call this directly from your main loop)
+void ImGui_ImplWGPU_RenderDrawData(ImDrawData* draw_data, WGPURenderPassEncoder pass_encoder)
+{
+    // Avoid rendering when minimized
+    if (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f)
+        return;
+
+    // FIXME: I'm assuming that this only gets called once per frame!
+    // If not, we can't just re-allocate the IB or VB, we'll have to do a proper allocator.
+    g_frameIndex = g_frameIndex + 1;
+    FrameResources* fr = &g_pFrameResources[g_frameIndex % g_numFramesInFlight];
+
+    // Create and grow vertex/index buffers if needed
+    if (fr->VertexBuffer == NULL || fr->VertexBufferSize < draw_data->TotalVtxCount)
+    {
+        SafeRelease(fr->VertexBuffer);
+        SafeRelease(fr->VertexBufferHost);
+        fr->VertexBufferSize = draw_data->TotalVtxCount + 5000;
+
+        WGPUBufferDescriptor vb_desc = {
+            nullptr,
+            "IMGUI Vertex buffer",
+            WGPUBufferUsage_CopyDst | WGPUBufferUsage_Vertex,
+            fr->VertexBufferSize * sizeof(ImDrawVert),
+            false
+        };
+        fr->VertexBuffer = wgpuDeviceCreateBuffer(g_wgpuDevice, &vb_desc);
+        if (!fr->VertexBuffer)
+            return;
+
+        fr->VertexBufferHost = new ImDrawVert[fr->VertexBufferSize];
+    }
+    if (fr->IndexBuffer == NULL || fr->IndexBufferSize < draw_data->TotalIdxCount)
+    {
+        SafeRelease(fr->IndexBuffer);
+        SafeRelease(fr->IndexBufferHost);
+        fr->IndexBufferSize = draw_data->TotalIdxCount + 10000;
+
+        WGPUBufferDescriptor ib_desc = {
+            nullptr,
+            "IMGUI Index buffer",
+            WGPUBufferUsage_CopyDst | WGPUBufferUsage_Index,
+            fr->IndexBufferSize * sizeof(ImDrawIdx),
+            false
+        };
+        fr->IndexBuffer = wgpuDeviceCreateBuffer(g_wgpuDevice, &ib_desc);
+        if (!fr->IndexBuffer)
+            return;
+
+        fr->IndexBufferHost = new ImDrawIdx[fr->IndexBufferSize];
+    }
+
+    // Upload vertex/index data into a single contiguous GPU buffer
+    ImDrawVert* vtx_dst = (ImDrawVert*)fr->VertexBufferHost;
+    ImDrawIdx* idx_dst = (ImDrawIdx*)fr->IndexBufferHost;
+    for (int n = 0; n < draw_data->CmdListsCount; n++)
+    {
+        const ImDrawList* cmd_list = draw_data->CmdLists[n];
+        memcpy(vtx_dst, cmd_list->VtxBuffer.Data, cmd_list->VtxBuffer.Size * sizeof(ImDrawVert));
+        memcpy(idx_dst, cmd_list->IdxBuffer.Data, cmd_list->IdxBuffer.Size * sizeof(ImDrawIdx));
+        vtx_dst += cmd_list->VtxBuffer.Size;
+        idx_dst += cmd_list->IdxBuffer.Size;
+    }
+    int64_t vb_write_size = ((char*)vtx_dst - (char*)fr->VertexBufferHost + 3) & ~3;
+    int64_t ib_write_size = ((char*)idx_dst - (char*)fr->IndexBufferHost  + 3) & ~3;
+    wgpuQueueWriteBuffer(wgpuDeviceGetDefaultQueue(g_wgpuDevice), fr->VertexBuffer, 0, fr->VertexBufferHost, vb_write_size);
+    wgpuQueueWriteBuffer(wgpuDeviceGetDefaultQueue(g_wgpuDevice), fr->IndexBuffer,  0, fr->IndexBufferHost,  ib_write_size);
+
+    // Setup desired render state
+    ImGui_ImplWGPU_SetupRenderState(draw_data, pass_encoder, fr);
+
+    // Render command lists
+    // (Because we merged all buffers into a single one, we maintain our own offset into them)
+    int global_vtx_offset = 0;
+    int global_idx_offset = 0;
+    ImVec2 clip_off = draw_data->DisplayPos;
+    for (int n = 0; n < draw_data->CmdListsCount; n++)
+    {
+        const ImDrawList* cmd_list = draw_data->CmdLists[n];
+        for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
+        {
+            const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
+            if (pcmd->UserCallback != NULL)
+            {
+                // User callback, registered via ImDrawList::AddCallback()
+                // (ImDrawCallback_ResetRenderState is a special callback value used by the user to request the renderer to reset render state.)
+                if (pcmd->UserCallback == ImDrawCallback_ResetRenderState)
+                    ImGui_ImplWGPU_SetupRenderState(draw_data, pass_encoder, fr);
+                else
+                    pcmd->UserCallback(cmd_list, pcmd);
+            }
+            else
+            {
+                // Bind custom texture
+                auto bind_group = g_resources.ImageBindGroups.GetVoidPtr(ImHashData(&pcmd->TextureId, sizeof(ImTextureID)));
+                if (bind_group) {
+                    wgpuRenderPassEncoderSetBindGroup(pass_encoder, 1, (WGPUBindGroup)bind_group, 0, NULL);
+                }
+                else {
+                    WGPUBindGroup image_bind_group = ImGui_ImplWGPU_CreateImageBindGroup(g_resources.ImageBindGroupLayout, (WGPUTextureView) pcmd->TextureId);
+                    g_resources.ImageBindGroups.SetVoidPtr(ImHashData(&pcmd->TextureId, sizeof(ImTextureID)), image_bind_group);
+
+                    wgpuRenderPassEncoderSetBindGroup(pass_encoder, 1, image_bind_group, 0, NULL);
+                }
+
+                // Apply Scissor, Bind texture, Draw
+                uint32_t clip_rect[4];
+                clip_rect[0] = static_cast<uint32_t>(pcmd->ClipRect.x - clip_off.x);
+                clip_rect[1] = static_cast<uint32_t>(pcmd->ClipRect.y - clip_off.y);
+                clip_rect[2] = static_cast<uint32_t>(pcmd->ClipRect.z - clip_off.x);
+                clip_rect[3] = static_cast<uint32_t>(pcmd->ClipRect.w - clip_off.y);
+                wgpuRenderPassEncoderSetScissorRect(pass_encoder, clip_rect[0], clip_rect[1], clip_rect[2] - clip_rect[0], clip_rect[3] - clip_rect[1]);
+                wgpuRenderPassEncoderDrawIndexed(pass_encoder, pcmd->ElemCount, 1, pcmd->IdxOffset + global_idx_offset, pcmd->VtxOffset + global_vtx_offset, 0);
+            }
+        }
+        global_idx_offset += cmd_list->IdxBuffer.Size;
+        global_vtx_offset += cmd_list->VtxBuffer.Size;
+    }
+}
+
+static WGPUBuffer ImGui_ImplWGPU_CreateBufferFromData(const WGPUDevice& device, const void* data, uint64_t size, WGPUBufferUsage usage)
+{
+    WGPUBufferDescriptor descriptor = {};
+    descriptor.size = size;
+    descriptor.usage = usage | WGPUBufferUsage_CopyDst;
+    WGPUBuffer buffer = wgpuDeviceCreateBuffer(device, &descriptor);
+
+    WGPUQueue queue = wgpuDeviceGetDefaultQueue(g_wgpuDevice);
+    wgpuQueueWriteBuffer(queue, buffer, 0, data, size);
+    return buffer;
+}
+
+
+static void ImGui_ImplWGPU_CreateFontsTexture()
+{
+    // Build texture atlas
+    ImGuiIO& io = ImGui::GetIO();
+    unsigned char* pixels;
+    int width, height, size_pp;
+    io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height, &size_pp);
+
+    // Upload texture to graphics system
+    {
+        WGPUTextureDescriptor tex_desc = {};
+        tex_desc.label = "IMGUI Font Texture";
+        tex_desc.dimension = WGPUTextureDimension_2D;
+        tex_desc.size.width = width;
+        tex_desc.size.height = height;
+        tex_desc.size.depth = 1;
+        tex_desc.sampleCount = 1;
+        tex_desc.format = WGPUTextureFormat_RGBA8Unorm;
+        tex_desc.mipLevelCount = 1;
+        tex_desc.usage = WGPUTextureUsage_CopyDst | WGPUTextureUsage_Sampled;
+        g_resources.FontTexture = wgpuDeviceCreateTexture(g_wgpuDevice, &tex_desc);
+
+        WGPUTextureViewDescriptor tex_view_desc = {};
+        tex_view_desc.format = WGPUTextureFormat_RGBA8Unorm;
+        tex_view_desc.dimension = WGPUTextureViewDimension_2D;
+        tex_view_desc.baseMipLevel = 0;
+        tex_view_desc.mipLevelCount = 1;
+        tex_view_desc.baseArrayLayer = 0;
+        tex_view_desc.arrayLayerCount = 1;
+        tex_view_desc.aspect = WGPUTextureAspect_All;
+        g_resources.FontTextureView = wgpuTextureCreateView(g_resources.FontTexture, &tex_view_desc);
+    }
+
+    // Upload texture data
+    {
+        WGPUBuffer staging_buffer = ImGui_ImplWGPU_CreateBufferFromData(g_wgpuDevice, pixels, static_cast<uint32_t>(width * size_pp * height), WGPUBufferUsage_CopySrc);
+
+        WGPUBufferCopyView bufferCopyView = {};
+        bufferCopyView.buffer = staging_buffer;
+        bufferCopyView.layout.offset = 0;
+        bufferCopyView.layout.bytesPerRow = width * size_pp;
+        bufferCopyView.layout.rowsPerImage = height;
+
+        WGPUTextureCopyView textureCopyView = {};
+        textureCopyView.texture = g_resources.FontTexture;
+        textureCopyView.mipLevel = 0;
+        textureCopyView.origin = { 0, 0, 0 };
+#ifndef __EMSCRIPTEN__
+        textureCopyView.aspect = WGPUTextureAspect_All;
+#endif
+
+        WGPUExtent3D copySize = { static_cast<uint32_t>(width), static_cast<uint32_t>(height), 1 };
+
+        WGPUCommandEncoderDescriptor enc_desc = {};
+        WGPUCommandEncoder encoder = wgpuDeviceCreateCommandEncoder(g_wgpuDevice, &enc_desc);
+        wgpuCommandEncoderCopyBufferToTexture(encoder, &bufferCopyView, &textureCopyView, &copySize);
+        WGPUCommandBufferDescriptor cmd_buf_desc = {};
+        WGPUCommandBuffer copy = wgpuCommandEncoderFinish(encoder, &cmd_buf_desc);
+        WGPUQueue queue = wgpuDeviceGetDefaultQueue(g_wgpuDevice);
+        wgpuQueueSubmit(queue, 1, &copy);
+
+        wgpuCommandEncoderRelease(encoder);
+        wgpuBufferRelease(staging_buffer);
+    }
+
+    // Create the associated sampler
+    {
+        WGPUSamplerDescriptor sampler_desc = {};
+        sampler_desc.minFilter = WGPUFilterMode_Linear;
+        sampler_desc.magFilter = WGPUFilterMode_Linear;
+        sampler_desc.mipmapFilter = WGPUFilterMode_Linear;
+        sampler_desc.addressModeU = WGPUAddressMode_Repeat;
+        sampler_desc.addressModeV = WGPUAddressMode_Repeat;
+        sampler_desc.addressModeW = WGPUAddressMode_Repeat;
+        g_resources.Sampler = wgpuDeviceCreateSampler(g_wgpuDevice, &sampler_desc);
+    }
+
+    // Store our identifier
+    static_assert(sizeof(ImTextureID) >= sizeof(g_resources.FontTexture), "Can't pack descriptor handle into TexID, 32-bit not supported yet.");
+    io.Fonts->TexID = (ImTextureID)g_resources.FontTextureView;
+}
+
+static void ImGui_ImplWGPU_CreateUniformBuffer()
+{
+    WGPUBufferDescriptor ub_desc = {
+        nullptr,
+        "IMGUI Uniform buffer",
+        WGPUBufferUsage_CopyDst | WGPUBufferUsage_Uniform,
+        sizeof(Uniforms),
+        false
+    };
+    g_resources.Uniforms = wgpuDeviceCreateBuffer(g_wgpuDevice, &ub_desc);
+}
+
+bool ImGui_ImplWGPU_CreateDeviceObjects()
+{
+    if (!g_wgpuDevice)
+        return false;
+    if (g_pipelineState)
+        ImGui_ImplWGPU_InvalidateDeviceObjects();
+
+    // Create render pipeline
+    WGPURenderPipelineDescriptor graphics_pipeline_desc = {};
+
+    graphics_pipeline_desc.primitiveTopology = WGPUPrimitiveTopology_TriangleList;
+    graphics_pipeline_desc.sampleCount = 1;
+    graphics_pipeline_desc.sampleMask = UINT_MAX;
+
+
+    WGPUBindGroupLayoutEntry common_bg_layout_entries[2] = {};
+    common_bg_layout_entries[0].binding = 0;
+    common_bg_layout_entries[0].visibility = WGPUShaderStage_Vertex;
+    common_bg_layout_entries[0].type = WGPUBindingType_UniformBuffer;
+    common_bg_layout_entries[1].binding = 1;
+    common_bg_layout_entries[1].visibility = WGPUShaderStage_Fragment;
+    common_bg_layout_entries[1].type = WGPUBindingType_Sampler;
+
+    WGPUBindGroupLayoutEntry image_bg_layout_entries[1] = {};
+    image_bg_layout_entries[0].binding = 0;
+    image_bg_layout_entries[0].visibility = WGPUShaderStage_Fragment;
+    image_bg_layout_entries[0].type = WGPUBindingType_SampledTexture;
+
+    WGPUBindGroupLayoutDescriptor common_bg_layout_desc = {};
+    common_bg_layout_desc.entryCount = 2;
+    common_bg_layout_desc.entries = common_bg_layout_entries;
+
+    WGPUBindGroupLayoutDescriptor image_bg_layout_desc = {};
+    image_bg_layout_desc.entryCount = 1;
+    image_bg_layout_desc.entries = image_bg_layout_entries;
+
+    WGPUBindGroupLayout bg_layouts[2];
+    bg_layouts[0] = wgpuDeviceCreateBindGroupLayout(g_wgpuDevice, &common_bg_layout_desc);
+    bg_layouts[1] = wgpuDeviceCreateBindGroupLayout(g_wgpuDevice, &image_bg_layout_desc);
+
+    WGPUPipelineLayoutDescriptor layout_desc = {};
+    layout_desc.bindGroupLayoutCount = 2;
+    layout_desc.bindGroupLayouts = bg_layouts;
+    graphics_pipeline_desc.layout = wgpuDeviceCreatePipelineLayout(g_wgpuDevice, &layout_desc);
+
+    // Create the vertex shader
+    WGPUProgrammableStageDescriptor vertex_shader_desc = ImGui_ImplWGPU_CreateShaderModule(__glsl_shader_vert_spv, sizeof(__glsl_shader_vert_spv) / sizeof(uint32_t));
+    graphics_pipeline_desc.vertexStage = vertex_shader_desc;
+
+    // Vertex input configuration
+    WGPUVertexAttributeDescriptor attribute_binding_desc[] = {
+        { WGPUVertexFormat_Float2,     (uint64_t)IM_OFFSETOF(ImDrawVert, pos), 0 },
+        { WGPUVertexFormat_Float2,     (uint64_t)IM_OFFSETOF(ImDrawVert, uv),  1 },
+        { WGPUVertexFormat_UChar4Norm, (uint64_t)IM_OFFSETOF(ImDrawVert, col), 2 },
+    };
+
+    WGPUVertexBufferLayoutDescriptor buffer_binding_desc;
+    buffer_binding_desc.arrayStride = sizeof(ImDrawVert);
+    buffer_binding_desc.stepMode = WGPUInputStepMode_Vertex;
+    buffer_binding_desc.attributeCount = 3;
+    buffer_binding_desc.attributes = attribute_binding_desc;
+
+    WGPUVertexStateDescriptor vertex_state_desc = {};
+    vertex_state_desc.indexFormat = WGPUIndexFormat_Undefined;
+    vertex_state_desc.vertexBufferCount = 1;
+    vertex_state_desc.vertexBuffers = &buffer_binding_desc;
+
+    graphics_pipeline_desc.vertexState = &vertex_state_desc;
+
+    // Create the pixel shader
+    WGPUProgrammableStageDescriptor pixel_shader_desc = ImGui_ImplWGPU_CreateShaderModule(__glsl_shader_frag_spv, sizeof(__glsl_shader_frag_spv) / sizeof(uint32_t));
+    graphics_pipeline_desc.fragmentStage = &pixel_shader_desc;
+
+    // Create the blending setup
+    WGPUColorStateDescriptor color_state = {};
+    {
+        color_state.format = g_renderTargetFormat;
+        color_state.alphaBlend.operation = WGPUBlendOperation_Add;
+        color_state.alphaBlend.srcFactor = WGPUBlendFactor_OneMinusSrcAlpha;
+        color_state.alphaBlend.dstFactor = WGPUBlendFactor_Zero;
+        color_state.colorBlend.operation = WGPUBlendOperation_Add;
+        color_state.colorBlend.srcFactor = WGPUBlendFactor_SrcAlpha;
+        color_state.colorBlend.dstFactor = WGPUBlendFactor_OneMinusSrcAlpha;
+        color_state.writeMask = WGPUColorWriteMask_All;
+
+        graphics_pipeline_desc.colorStateCount = 1;
+        graphics_pipeline_desc.colorStates = &color_state;
+        graphics_pipeline_desc.alphaToCoverageEnabled = false;
+    }
+
+    // Create the rasterizer state
+    WGPURasterizationStateDescriptor raster_desc = {};
+    {
+        raster_desc.cullMode = WGPUCullMode_None;
+        raster_desc.frontFace = WGPUFrontFace_CW;
+        raster_desc.depthBias = 0;
+        raster_desc.depthBiasClamp = 0;
+        raster_desc.depthBiasSlopeScale = 0;
+        graphics_pipeline_desc.rasterizationState = &raster_desc;
+    }
+
+    // Create depth-stencil State
+    WGPUDepthStencilStateDescriptor depth_desc = {};
+    {
+        // Configure disabled state
+        depth_desc.format = WGPUTextureFormat_Undefined;
+
+        depth_desc.depthWriteEnabled = true;
+        depth_desc.depthCompare = WGPUCompareFunction_Always;
+        depth_desc.stencilReadMask = 0;
+        depth_desc.stencilWriteMask = 0;
+        depth_desc.stencilBack.compare = WGPUCompareFunction_Always;
+        depth_desc.stencilBack.failOp = WGPUStencilOperation_Keep;
+        depth_desc.stencilBack.depthFailOp = WGPUStencilOperation_Keep;
+        depth_desc.stencilBack.passOp = WGPUStencilOperation_Keep;
+        depth_desc.stencilFront.compare = WGPUCompareFunction_Always;
+        depth_desc.stencilFront.failOp = WGPUStencilOperation_Keep;
+        depth_desc.stencilFront.depthFailOp = WGPUStencilOperation_Keep;
+        depth_desc.stencilFront.passOp = WGPUStencilOperation_Keep;
+
+        // No depth buffer corresponds to no configuration
+        graphics_pipeline_desc.depthStencilState = nullptr;
+    }
+
+    g_pipelineState = wgpuDeviceCreateRenderPipeline(g_wgpuDevice, &graphics_pipeline_desc);
+
+    ImGui_ImplWGPU_CreateFontsTexture();
+    ImGui_ImplWGPU_CreateUniformBuffer();
+
+    // Create resource bind group
+    WGPUBindGroupEntry common_bg_entries[] = {
+        { 0, g_resources.Uniforms, 0, sizeof(Uniforms), 0, 0 },
+        { 1, 0, 0, 0, g_resources.Sampler, 0 },
+    };
+
+    WGPUBindGroupDescriptor common_bg_descriptor = {};
+    common_bg_descriptor.layout = bg_layouts[0];
+    common_bg_descriptor.entryCount = sizeof(common_bg_entries) / sizeof(WGPUBindGroupEntry);
+    common_bg_descriptor.entries = common_bg_entries;
+    g_resources.CommonBindGroup = wgpuDeviceCreateBindGroup(g_wgpuDevice, &common_bg_descriptor);
+    g_resources.ImageBindGroupLayout = bg_layouts[1];
+
+    WGPUBindGroup image_bind_group = ImGui_ImplWGPU_CreateImageBindGroup(bg_layouts[1], g_resources.FontTextureView);
+    g_resources.ImageBindGroup = image_bind_group;
+    g_resources.ImageBindGroups.SetVoidPtr(ImHashData(&g_resources.FontTextureView, sizeof(ImTextureID)), image_bind_group);
+
+    SafeRelease(vertex_shader_desc.module);
+    SafeRelease(pixel_shader_desc.module);
+    SafeRelease(bg_layouts[0]);
+
+    return true;
+}
+
+void ImGui_ImplWGPU_InvalidateDeviceObjects()
+{
+    if (!g_wgpuDevice)
+        return;
+
+    SafeRelease(g_pipelineState);
+    SafeRelease(g_resources);
+
+    ImGuiIO& io = ImGui::GetIO();
+    io.Fonts->TexID = NULL; // We copied g_pFontTextureView to io.Fonts->TexID so let's clear that as well.
+
+    for (unsigned int i = 0; i < g_numFramesInFlight; i++)
+    {
+        SafeRelease(g_pFrameResources[i]);
+    }
+}
+
+bool ImGui_ImplWGPU_Init(WGPUDevice device, int num_frames_in_flight, WGPUTextureFormat rt_format)
+{
+    // Setup back-end capabilities flags
+    ImGuiIO& io = ImGui::GetIO();
+    io.BackendRendererName = "imgui_impl_webgpu";
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
+
+    g_wgpuDevice = device;
+    g_renderTargetFormat = rt_format;
+    g_pFrameResources = new FrameResources[num_frames_in_flight];
+    g_numFramesInFlight = num_frames_in_flight;
+    g_frameIndex = UINT_MAX;
+
+    g_resources.FontTexture = NULL;
+    g_resources.FontTextureView = NULL;
+    g_resources.Sampler = NULL;
+    g_resources.Uniforms = NULL;
+    g_resources.CommonBindGroup = NULL;
+    g_resources.ImageBindGroupLayout = NULL;
+    g_resources.ImageBindGroups.Data.reserve(100);
+    g_resources.ImageBindGroup = NULL;
+
+    // Create buffers with a default size (they will later be grown as needed)
+    for (int i = 0; i < num_frames_in_flight; i++)
+    {
+        FrameResources* fr = &g_pFrameResources[i];
+        fr->IndexBuffer = NULL;
+        fr->VertexBuffer = NULL;
+        fr->IndexBufferHost = NULL;
+        fr->VertexBufferHost = NULL;
+        fr->IndexBufferSize = 10000;
+        fr->VertexBufferSize = 5000;
+    }
+
+    return true;
+}
+
+void ImGui_ImplWGPU_Shutdown()
+{
+    ImGui_ImplWGPU_InvalidateDeviceObjects();
+    delete[] g_pFrameResources;
+    g_pFrameResources = NULL;
+    g_wgpuDevice = NULL;
+    g_numFramesInFlight = 0;
+    g_frameIndex = UINT_MAX;
+}
+
+void ImGui_ImplWGPU_NewFrame()
+{
+    if (!g_pipelineState)
+        ImGui_ImplWGPU_CreateDeviceObjects();
+}

backends/imgui_impl_wgpu.h

@@ -0,0 +1,26 @@
+// dear imgui: Renderer for WebGPU
+// This needs to be used along with a Platform Binding (e.g. GLFW)
+
+// Implemented features:
+//  [X] Renderer: User texture binding. Use 'WGPUTextureView' as ImTextureID. Read the FAQ about ImTextureID!
+//  [X] Renderer: Support for large meshes (64k+ vertices) with 16-bit indices.
+
+// You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
+// 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
+
+#pragma once
+#include "imgui.h"      // IMGUI_IMPL_API
+
+// WebGPU
+#include <webgpu/webgpu.h>
+
+// cmd_list is the command list that the implementation will use to render imgui draw lists.
+IMGUI_IMPL_API bool ImGui_ImplWGPU_Init(WGPUDevice device, int num_frames_in_flight, WGPUTextureFormat rt_format);
+IMGUI_IMPL_API void ImGui_ImplWGPU_Shutdown();
+IMGUI_IMPL_API void ImGui_ImplWGPU_NewFrame();
+IMGUI_IMPL_API void ImGui_ImplWGPU_RenderDrawData(ImDrawData* draw_data, WGPURenderPassEncoder pass_encoder);
+
+// Use if you want to reset your rendering device without losing Dear ImGui state.
+IMGUI_IMPL_API void ImGui_ImplWGPU_InvalidateDeviceObjects();
+IMGUI_IMPL_API bool ImGui_ImplWGPU_CreateDeviceObjects();

docs/BACKENDS.md

@@ -68,6 +68,7 @@ List of Renderer Backends:
     imgui_impl_opengl2.cpp    ; OpenGL 2 (legacy, fixed pipeline <- don't use with modern OpenGL context)
     imgui_impl_opengl3.cpp    ; OpenGL 3/4, OpenGL ES 2, OpenGL ES 3 (modern programmable pipeline)
     imgui_impl_vulkan.cpp     ; Vulkan
+    imgui_impl_wgpu.cpp       ; WebGPU
 
 List of high-level Frameworks Backends (combining Platform + Renderer):
 

docs/CHANGELOG.txt

@@ -94,6 +94,7 @@ Breaking Changes:
   confusion with Tables API. Keep redirection enums (will obsolete). (#125, #513, #913, #1204, #1444, #2142, #2707)
 - Renamed io.ConfigWindowsMemoryCompactTimer to io.ConfigMemoryCompactTimer as the feature now applies
   to other data structures. (#2636)
+- Backends: WebGPU: Added backend for WebGPU support in imgui_impl_wgpu [@bfierz]
 
 Other Changes:
 

docs/EXAMPLES.md

@@ -98,6 +98,10 @@ Emcripten + SDL2 + OpenGL3+/ES2/ES3 example. <BR>
 Note that other examples based on SDL or GLFW + OpenGL could easily be modified to work with Emscripten.
 We provide this to make the Emscripten differences obvious, and have them not pollute all other examples.
 
+[example_emscripten_wgpu/](https://github.com/ocornut/imgui/blob/master/examples/example_emscripten_wgpu/) <BR>
+Emcripten + GLFW + WebGPU example. <BR>
+= main.cpp + imgui_impl_glfw.cpp + imgui_impl_wgpu.cpp
+
 [example_glfw_metal/](https://github.com/ocornut/imgui/blob/master/examples/example_glfw_metal/) <BR>
 GLFW (Mac) + Metal example. <BR>
 = main.mm + imgui_impl_glfw.cpp + imgui_impl_metal.mm

examples/example_emscripten_wgpu/Makefile

@@ -0,0 +1,80 @@
+#
+# Makefile to use with emscripten
+# See https://emscripten.org/docs/getting_started/downloads.html
+# for installation instructions.
+#
+# This Makefile assumes you have loaded emscripten's environment.
+# (On Windows, you may need to execute emsdk_env.bat or encmdprompt.bat ahead)
+#
+# Running `make` will produce two files:
+#  - example_emscripten_wgpu.js
+#  - example_emscripten_wgpu.wasm
+#
+# All three are needed to run the demo.
+
+CC = emcc
+CXX = em++
+EXE = example_emscripten_wgpu.js
+IMGUI_DIR = ../..
+SOURCES = main.cpp
+SOURCES += $(IMGUI_DIR)/imgui.cpp $(IMGUI_DIR)/imgui_demo.cpp $(IMGUI_DIR)/imgui_draw.cpp $(IMGUI_DIR)/imgui_widgets.cpp
+SOURCES += $(IMGUI_DIR)/backends/imgui_impl_glfw.cpp $(IMGUI_DIR)/backends/imgui_impl_wgpu.cpp
+OBJS = $(addsuffix .o, $(basename $(notdir $(SOURCES))))
+UNAME_S := $(shell uname -s)
+
+##---------------------------------------------------------------------
+## EMSCRIPTEN OPTIONS
+##---------------------------------------------------------------------
+
+EMS += -s USE_GLFW=3 -s USE_WEBGPU=1 -s WASM=1
+EMS += -s ALLOW_MEMORY_GROWTH=1
+EMS += -s DISABLE_EXCEPTION_CATCHING=1 -s NO_EXIT_RUNTIME=0
+EMS += -s ASSERTIONS=1
+
+# Emscripten allows preloading a file or folder to be accessible at runtime.
+# The Makefile for this example project suggests embedding the misc/fonts/ folder into our application, it will then be accessible as "/fonts"
+# See documentation for more details: https://emscripten.org/docs/porting/files/packaging_files.html
+# (Default value is 0. Set to 1 to enable file-system and include the misc/fonts/ folder as part of the build.)
+USE_FILE_SYSTEM ?= 0
+ifeq ($(USE_FILE_SYSTEM), 0)
+EMS += -s NO_FILESYSTEM=1 -DIMGUI_DISABLE_FILE_FUNCTIONS
+endif
+ifeq ($(USE_FILE_SYSTEM), 1)
+LDFLAGS += --no-heap-copy --preload-file ../../misc/fonts@/fonts
+endif
+
+##---------------------------------------------------------------------
+## FINAL BUILD FLAGS
+##---------------------------------------------------------------------
+
+CPPFLAGS += -I$(IMGUI_DIR)/ -I$(IMGUI_DIR)/backends
+#CPPFLAGS += -g
+CPPFLAGS += -Wall -Wformat -Os
+CPPFLAGS += $(EMS)
+LIBS += $(EMS)
+#LDFLAGS += --shell-file shell_minimal.html
+
+##---------------------------------------------------------------------
+## BUILD RULES
+##---------------------------------------------------------------------
+
+%.o:%.cpp
+	$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $<
+
+%.o:../%.cpp
+	$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $<
+
+%.o:$(IMGUI_DIR)/%.cpp
+	$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $<
+
+%.o:$(IMGUI_DIR)/backends/%.cpp
+	$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $<
+
+all: $(EXE)
+	@echo Build complete for $(EXE)
+
+$(EXE): $(OBJS)
+	$(CXX) -o $@ $^ $(LIBS) $(LDFLAGS)
+
+clean:
+	rm -f $(EXE) $(OBJS) *.js *.wasm *.wasm.pre

examples/example_emscripten_wgpu/README.md

@@ -0,0 +1,10 @@
+
+# How to Build
+
+- You need to install Emscripten from https://emscripten.org/docs/getting_started/downloads.html, and have the environment variables set, as described in https://emscripten.org/docs/getting_started/downloads.html#installation-instructions
+
+- Depending on your configuration, in Windows you may need to run `emsdk/emsdk_env.bat` in your console to access the Emscripten command-line tools.
+
+- Then build using `make` while in the `example_emscripten_wgpu/` directory.
+
+- Requires Emscripten 2.0.10 (December 2020) due to GLFW adaptations

examples/example_emscripten_wgpu/example_emscripten_wgpu.html

@@ -0,0 +1,80 @@
+<!doctype html>
+<html lang="en-us">
+  <head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, minimum-scale=1, user-scalable=no"/>
+    <title>Dear ImGui Emscripten example</title>
+    <style>
+        body { margin: 0; background-color: black }
+        .emscripten {
+            position: absolute;
+            top: 0px;
+            left: 0px;
+            margin: 0px;
+            border: 0;
+            width: 100%;
+            height: 100%;
+            overflow: hidden;
+            display: block;
+            image-rendering: optimizeSpeed;
+            image-rendering: -moz-crisp-edges;
+            image-rendering: -o-crisp-edges;
+            image-rendering: -webkit-optimize-contrast;
+            image-rendering: optimize-contrast;
+            image-rendering: crisp-edges;
+            image-rendering: pixelated;
+            -ms-interpolation-mode: nearest-neighbor;
+        }
+    </style>
+  </head>
+  <body>
+    <canvas class="emscripten" id="canvas" oncontextmenu="event.preventDefault()"></canvas>
+    <script type='text/javascript'>
+      var Module;
+      (async () => {
+        Module = {
+          preRun: [],
+          postRun: [],
+          print: (function() {
+              return function(text) {
+                  text = Array.prototype.slice.call(arguments).join(' ');
+                  console.log(text);
+              };
+          })(),
+          printErr: function(text) {
+              text = Array.prototype.slice.call(arguments).join(' ');
+              console.error(text);
+          },
+          canvas: (function() {
+              var canvas = document.getElementById('canvas');
+              //canvas.addEventListener("webglcontextlost", function(e) { alert('FIXME: WebGL context lost, please reload the page'); e.preventDefault(); }, false);
+              return canvas;
+          })(),
+          setStatus: function(text) {
+              console.log("status: " + text);
+          },
+          monitorRunDependencies: function(left) {
+              // no run dependencies to log
+          }
+        };
+        window.onerror = function() {
+          console.log("onerror: " + event);
+        };
+
+      // Initialize the graphics adapter
+      {
+          const adapter = await navigator.gpu.requestAdapter();
+          const device = await adapter.requestDevice();
+          Module.preinitializedWebGPUDevice = device;
+      }
+
+      {
+          const js = document.createElement('script');
+          js.async = true;
+          js.src = "example_emscripten_wgpu.js";
+          document.body.appendChild(js);
+      }
+      })();
+    </script>
+  </body>
+</html>

examples/example_emscripten_wgpu/main.cpp

@@ -0,0 +1,257 @@
+// 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/)
+// 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 mostly the same code as the SDL2 + OpenGL3 example, simply with the modifications needed to run on Emscripten.
+// It is possible to combine both code into a single source file that will compile properly on Desktop and using Emscripten.
+// See https://github.com/ocornut/imgui/pull/2492 as an example on how to do just that.
+
+#include "imgui.h"
+#include "imgui_impl_glfw.h"
+#include "imgui_impl_wgpu.h"
+#include <stdio.h>
+#include <emscripten.h>
+#include <emscripten/html5.h>
+#include <emscripten/html5_webgpu.h>
+#include <GLFW/glfw3.h>
+#include <webgpu/webgpu.h>
+#include <webgpu/webgpu_cpp.h>
+
+// Global WebGPU required states
+static WGPUDevice    wgpu_device = NULL;
+static WGPUSurface   wgpu_surface = NULL;
+static WGPUSwapChain wgpu_swap_chain = NULL;
+
+static int           wgpu_swap_chain_width = 0;
+static int           wgpu_swap_chain_height = 0;
+
+// States tracked across render frames
+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);
+
+// Forward declartions
+bool init_wgpu();
+void main_loop(void* window);
+void print_glfw_error(int error, const char* description);
+void print_wgpu_error(WGPUErrorType error_type, const char* message, void*);
+
+int main(int, char**)
+{
+    glfwSetErrorCallback(print_glfw_error);
+    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", NULL, NULL);
+    if (!window) {
+        glfwTerminate();
+        return 1;
+    }
+
+    // Initialize the WebGPU environment
+    if (!init_wgpu()) {
+        if (window)
+            glfwDestroyWindow(window);
+        glfwTerminate();
+        return 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
+
+    // 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 = NULL;
+
+    // Setup Dear ImGui style
+    ImGui::StyleColorsDark();
+    //ImGui::StyleColorsClassic();
+
+    // Setup Platform/Renderer backends
+    ImGui_ImplGlfw_InitForVulkan(window, true);
+    ImGui_ImplWGPU_Init(wgpu_device, 3, WGPUTextureFormat_RGBA8Unorm);
+
+    // 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.
+    // - 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/Roboto-Medium.ttf", 16.0f);
+    //io.Fonts->AddFontFromFileTTF("fonts/Cousine-Regular.ttf", 15.0f);
+    //io.Fonts->AddFontFromFileTTF("fonts/DroidSans.ttf", 16.0f);
+    //io.Fonts->AddFontFromFileTTF("fonts/ProggyTiny.ttf", 10.0f);
+    //ImFont* font = io.Fonts->AddFontFromFileTTF("fonts/ArialUni.ttf", 18.0f, NULL, io.Fonts->GetGlyphRangesJapanese());
+    //IM_ASSERT(font != NULL);
+#endif
+
+    // This function will directly return and extit he 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(main_loop, window, 0, false);
+
+    return 0;
+}
+
+bool init_wgpu()
+{
+    wgpu_device = emscripten_webgpu_get_device();
+    if (!wgpu_device)
+        return false;
+
+    wgpuDeviceSetUncapturedErrorCallback(wgpu_device, print_wgpu_error, nullptr);
+
+    // Use C++ wrapper due to malbehaviour in Emscripten.
+    // Some offset computation for wgpuInstanceCreateSurface in JavaScript
+    // seem to be inline with struct alignments in the C++ structure
+    wgpu::SurfaceDescriptorFromCanvasHTMLSelector html_surface_desc{};
+    html_surface_desc.selector = "#canvas";
+
+    wgpu::SurfaceDescriptor surface_desc{};
+    surface_desc.nextInChain = &html_surface_desc;
+
+    // Use 'null' instance
+    wgpu::Instance instance{};
+    wgpu_surface = instance.CreateSurface(&surface_desc).Release();
+
+    return true;
+}
+
+void main_loop(void* window)
+{
+    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_OutputAttachment;
+        swap_chain_desc.format = WGPUTextureFormat_RGBA8Unorm;
+        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();
+
+    // 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 created 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 / ImGui::GetIO().Framerate, ImGui::GetIO().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();
+    }
+    
+    // Render the generated ImGui frame
+    ImGui::Render();
+
+    WGPURenderPassColorAttachmentDescriptor color_attachments = {};
+    color_attachments.loadOp = WGPULoadOp_Clear;
+    color_attachments.storeOp = WGPUStoreOp_Store;
+    color_attachments.clearColor = { clear_color.x, clear_color.y, clear_color.z, clear_color.w };
+    color_attachments.attachment = 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);
+    wgpuRenderPassEncoderEndPass(pass);
+
+    WGPUCommandBufferDescriptor cmd_buffer_desc = {};
+    WGPUCommandBuffer cmd_buffer = wgpuCommandEncoderFinish(encoder, &cmd_buffer_desc);
+    WGPUQueue queue = wgpuDeviceGetDefaultQueue(wgpu_device);
+    wgpuQueueSubmit(queue, 1, &cmd_buffer);
+}
+
+void print_glfw_error(int error, const char* description)
+{
+    printf("Glfw Error %d: %s\n", error, description);
+}
+
+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);
+}