Backends: WebGPU: update to compile with Dawn and Emscripten's 4.0.10+ '--use-port=emdawnwebgpu' ports. (#8381, #8898)

backends/imgui_impl_wgpu.cpp

@@ -1,6 +1,6 @@
 // dear imgui: Renderer for WebGPU
-// This needs to be used along with a Platform Binding (e.g. GLFW)
-// (Please note that WebGPU is currently experimental, will not run on non-beta browsers, and may break.)
+// This needs to be used along with a Platform Binding (e.g. GLFW, SDL2, SDL3)
+// (Please note that WebGPU is a recent API, may not be supported by all browser, and its ecosystem is generally a mess)
 
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'WGPUTextureView' as ImTextureID. Read the FAQ about ImTextureID/ImTextureRef!
@@ -8,6 +8,8 @@
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
 //  [X] Renderer: Texture updates support for dynamic font system (ImGuiBackendFlags_RendererHasTextures).
 
+// Read imgui_impl_wgpu.h about how to use the IMGUI_IMPL_WEBGPU_BACKEND_WGPU or IMGUI_IMPL_WEBGPU_BACKEND_DAWN flags.
+
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
 // Learn about Dear ImGui:
@@ -18,6 +20,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2025-10-16: Update to compile with Dawn and Emscripten's 4.0.10+ '--use-port=emdawnwebgpu' ports. (#8381, #8898)
 //  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-06-12: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas. (#8465)
 //  2025-02-26: Recreate image bind groups during render. (#8426, #8046, #7765, #8027) + Update for latest webgpu-native changes.
@@ -46,20 +49,20 @@
 
 #include "imgui.h"
 
-// When targeting native platforms (i.e. NOT Emscripten), one of IMGUI_IMPL_WEBGPU_BACKEND_DAWN
-// or IMGUI_IMPL_WEBGPU_BACKEND_WGPU must be provided. See imgui_impl_wgpu.h for more details.
-#ifndef __EMSCRIPTEN__
-    #if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) == defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
-    #error exactly one of IMGUI_IMPL_WEBGPU_BACKEND_DAWN or IMGUI_IMPL_WEBGPU_BACKEND_WGPU must be defined!
-    #endif
-#else
-    #if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) || defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
-    #error neither IMGUI_IMPL_WEBGPU_BACKEND_DAWN nor IMGUI_IMPL_WEBGPU_BACKEND_WGPU may be defined if targeting emscripten!
-    #endif
-#endif
-
 #ifndef IMGUI_DISABLE
 #include "imgui_impl_wgpu.h"
+
+// One of IMGUI_IMPL_WEBGPU_BACKEND_DAWN or IMGUI_IMPL_WEBGPU_BACKEND_WGPU must be provided. See imgui_impl_wgpu.h for more details.
+#if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) == defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
+#error Exactly one of IMGUI_IMPL_WEBGPU_BACKEND_DAWN or IMGUI_IMPL_WEBGPU_BACKEND_WGPU must be defined!
+#endif
+
+// This condition is true when it's built with EMSCRIPTEN using -sUSE_WEBGPU=1 flag  (deprecated from 4.0.10)
+// This condition is false for all other 3 cases: WGPU-Native, DAWN-Native or DAWN-EMSCRIPTEN (using --use-port=emdawnwebgpu flag)
+#if defined(__EMSCRIPTEN__) && defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
+#define IMGUI_IMPL_WEBGPU_BACKEND_WGPU_EMSCRIPTEN
+#endif
+
 #include <limits.h>
 #include <webgpu/webgpu.h>
 
@@ -259,7 +262,7 @@ static WGPUProgrammableStageDescriptor ImGui_ImplWGPU_CreateShaderModule(const c
 {
     ImGui_ImplWGPU_Data* bd = ImGui_ImplWGPU_GetBackendData();
 
-#if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) || defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
+#if !defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU_EMSCRIPTEN)
     WGPUShaderSourceWGSL wgsl_desc = {};
     wgsl_desc.chain.sType = WGPUSType_ShaderSourceWGSL;
     wgsl_desc.code = { wgsl_source, WGPU_STRLEN };
@@ -275,7 +278,7 @@ static WGPUProgrammableStageDescriptor ImGui_ImplWGPU_CreateShaderModule(const c
     WGPUProgrammableStageDescriptor stage_desc = {};
     stage_desc.module = wgpuDeviceCreateShaderModule(bd->wgpuDevice, &desc);
 
-#if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) || defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
+#if !defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU_EMSCRIPTEN)
     stage_desc.entryPoint = { "main", WGPU_STRLEN };
 #else
     stage_desc.entryPoint = "main";
@@ -398,9 +401,10 @@ void ImGui_ImplWGPU_RenderDrawData(ImDrawData* draw_data, WGPURenderPassEncoder
         WGPUBufferDescriptor vb_desc =
         {
             nullptr,
+#if !defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU_EMSCRIPTEN)
+            { "Dear ImGui Vertex buffer", WGPU_STRLEN, },
+#else
             "Dear ImGui Vertex buffer",
-#if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) || defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
-            WGPU_STRLEN,
 #endif
             WGPUBufferUsage_CopyDst | WGPUBufferUsage_Vertex,
             MEMALIGN(fr->VertexBufferSize * sizeof(ImDrawVert), 4),
@@ -425,9 +429,10 @@ void ImGui_ImplWGPU_RenderDrawData(ImDrawData* draw_data, WGPURenderPassEncoder
         WGPUBufferDescriptor ib_desc =
         {
             nullptr,
+#if !defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU_EMSCRIPTEN)
+            { "Dear ImGui Index buffer", WGPU_STRLEN, },
+#else
             "Dear ImGui Index buffer",
-#if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) || defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
-            WGPU_STRLEN,
 #endif
             WGPUBufferUsage_CopyDst | WGPUBufferUsage_Index,
             MEMALIGN(fr->IndexBufferSize * sizeof(ImDrawIdx), 4),
@@ -560,7 +565,7 @@ void ImGui_ImplWGPU_UpdateTexture(ImTextureData* tex)
 
         // Create texture
         WGPUTextureDescriptor tex_desc = {};
-#if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) || defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
+#if !defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU_EMSCRIPTEN)
         tex_desc.label = { "Dear ImGui Texture", WGPU_STRLEN };
 #else
         tex_desc.label = "Dear ImGui Texture";
@@ -605,7 +610,7 @@ void ImGui_ImplWGPU_UpdateTexture(ImTextureData* tex)
 
         // Update full texture or selected blocks. We only ever write to textures regions which have never been used before!
         // This backend choose to use tex->UpdateRect but you can use tex->Updates[] to upload individual regions.
-#if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) || defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
+#if !defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU_EMSCRIPTEN)
         WGPUTexelCopyTextureInfo dst_view = {};
 #else
         WGPUImageCopyTexture dst_view = {};
@@ -614,7 +619,7 @@ void ImGui_ImplWGPU_UpdateTexture(ImTextureData* tex)
         dst_view.mipLevel = 0;
         dst_view.origin = { (uint32_t)upload_x, (uint32_t)upload_y, 0 };
         dst_view.aspect = WGPUTextureAspect_All;
-#if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) || defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
+#if !defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU_EMSCRIPTEN)
         WGPUTexelCopyBufferLayout layout = {};
 #else
         WGPUTextureDataLayout layout = {};
@@ -636,9 +641,10 @@ static void ImGui_ImplWGPU_CreateUniformBuffer()
     WGPUBufferDescriptor ub_desc =
     {
         nullptr,
+#if !defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU_EMSCRIPTEN)
+        { "Dear ImGui Uniform buffer", WGPU_STRLEN, },
+#else
         "Dear ImGui Uniform buffer",
-#if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) || defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
-        WGPU_STRLEN,
 #endif
         WGPUBufferUsage_CopyDst | WGPUBufferUsage_Uniform,
         MEMALIGN(sizeof(Uniforms), 16),
@@ -751,7 +757,7 @@ bool ImGui_ImplWGPU_CreateDeviceObjects()
     // Create depth-stencil State
     WGPUDepthStencilState depth_stencil_state = {};
     depth_stencil_state.format = bd->depthStencilFormat;
-#if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) || defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
+#if !defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU_EMSCRIPTEN)
     depth_stencil_state.depthWriteEnabled = WGPUOptionalBool_False;
 #else
     depth_stencil_state.depthWriteEnabled = false;
@@ -833,14 +839,18 @@ bool ImGui_ImplWGPU_Init(ImGui_ImplWGPU_InitInfo* init_info)
     // Setup backend capabilities flags
     ImGui_ImplWGPU_Data* bd = IM_NEW(ImGui_ImplWGPU_Data)();
     io.BackendRendererUserData = (void*)bd;
+#if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN)
 #if defined(__EMSCRIPTEN__)
-    io.BackendRendererName = "imgui_impl_webgpu_emscripten";
-#elif defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN)
-    io.BackendRendererName = "imgui_impl_webgpu_dawn";
+    io.BackendRendererName = "imgui_impl_wgpu (Dawn, Emscripten)"; // compiled & linked using EMSCRIPTEN with "--use-port=emdawnwebgpu" flag
+#else
+    io.BackendRendererName = "imgui_impl_wgpu (Dawn, Native)";
+#endif
 #elif defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
-    io.BackendRendererName = "imgui_impl_webgpu_wgpu";
+#if defined(__EMSCRIPTEN__)
+    io.BackendRendererName = "imgui_impl_wgpu (WGPU, Emscripten)"; // linked using EMSCRIPTEN with "-sUSE_WEBGPU=1" flag, deprecated from EMSCRIPTEN 4.0.10
 #else
-    io.BackendRendererName = "imgui_impl_webgpu";
+    io.BackendRendererName = "imgui_impl_wgpu (WGPU, Native)";
+#endif
 #endif
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
     io.BackendFlags |= ImGuiBackendFlags_RendererHasTextures;   // We can honor ImGuiPlatformIO::Textures[] requests during render.

backends/imgui_impl_wgpu.h

@@ -1,11 +1,14 @@
 // dear imgui: Renderer for WebGPU
-// This needs to be used along with a Platform Binding (e.g. GLFW)
-// (Please note that WebGPU is currently experimental, will not run on non-beta browsers, and may break.)
+// This needs to be used along with a Platform Binding (e.g. GLFW, SDL2, SDL3)
+// (Please note that WebGPU is a recent API, may not be supported by all browser, and its ecosystem is generally a mess)
 
-// Important note to dawn and/or wgpu users: when targeting native platforms (i.e. NOT emscripten),
-// one of IMGUI_IMPL_WEBGPU_BACKEND_DAWN or IMGUI_IMPL_WEBGPU_BACKEND_WGPU must be provided.
+// When targeting native platforms:
+//  - One of IMGUI_IMPL_WEBGPU_BACKEND_DAWN or IMGUI_IMPL_WEBGPU_BACKEND_WGPU *must* be provided.
+// When targeting Emscripten:
+//  - We now defaults to IMGUI_IMPL_WEBGPU_BACKEND_DAWN is Emscripten version is 4.0.10+, which correspond to using Emscripten '--use-port=emdawnwebgpu'.
+//  - We can still define IMGUI_IMPL_WEBGPU_BACKEND_WGPU to use Emscripten '-s USE_WEBGPU=1' which is marked as obsolete by Emscripten.
 // Add #define to your imconfig.h file, or as a compilation flag in your build system.
-// This requirement will be removed once WebGPU stabilizes and backends converge on a unified interface.
+// This requirement may be removed once WebGPU stabilizes and backends converge on a unified interface.
 //#define IMGUI_IMPL_WEBGPU_BACKEND_DAWN
 //#define IMGUI_IMPL_WEBGPU_BACKEND_WGPU
 
@@ -27,6 +30,16 @@
 #include "imgui.h"          // IMGUI_IMPL_API
 #ifndef IMGUI_DISABLE
 
+// Setup Emscripten default if not specified.
+#if defined(__EMSCRIPTEN__) && !defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) && !defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
+#include <emscripten/version.h>
+#if (__EMSCRIPTEN_major__ >= 4) && (__EMSCRIPTEN_minor__ >= 0) && (__EMSCRIPTEN_tiny__ >= 10)
+#define IMGUI_IMPL_WEBGPU_BACKEND_DAWN
+#else
+#define IMGUI_IMPL_WEBGPU_BACKEND_WGPU
+#endif
+#endif
+
 #include <webgpu/webgpu.h>
 
 // Initialization data, for ImGui_ImplWGPU_Init()

docs/CHANGELOG.txt

@@ -53,6 +53,11 @@ Other Changes:
   resizing the parent window while keeping the multi-line field active (which is
   most typically achieved when resizing programmatically or via a docking layout
   reacting to a platform window resize). (#3237, #9007) [@anton-kl, @ocornut]
+- Backends: WebGPU: update to compile with Dawn and Emscripten's 4.0.10+
+  '--use-port=emdawnwebgpu' ports. (#8381, #8898) [@brutpitt, @trbabb]
+  When using Emscripten 4.0.10+, backend now defaults to IMGUI_IMPL_WEBGPU_BACKEND_DAWN
+  instead of IMGUI_IMPL_WEBGPU_BACKEND_WGPU, if neither are specified.
+  (note: examples application were not updated yet)
 
 
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