Backends: WGPU: add IMGUI_IMPL_WEBGPU_BACKEND_DAWN/IMGUI_IMPL_WEBGPU_…

…BACKEND_WGPU to support more targets. (#7977, #7969, #6602, #6188, #7523)
ocornut · Sep 16, 2024 · 1ac162f · 1ac162f
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diff --git a/backends/imgui_impl_wgpu.cpp b/backends/imgui_impl_wgpu.cpp
@@ -16,6 +16,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2024-09-16: Added support for optional IMGUI_IMPL_WEBGPU_BACKEND_DAWN / IMGUI_IMPL_WEBGPU_BACKEND_WGPU define to handle ever-changing native implementations. (#7977)
 //  2024-01-22: Added configurable PipelineMultisampleState struct. (#7240)
 //  2024-01-22: (Breaking) ImGui_ImplWGPU_Init() now takes a ImGui_ImplWGPU_InitInfo structure instead of variety of parameters, allowing for easier further changes.
 //  2024-01-22: Fixed pipeline layout leak. (#7245)
@@ -35,6 +36,18 @@
 //  2021-02-18: Change blending equation to preserve alpha in output buffer.
 //  2021-01-28: Initial version.
 
+// 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
+
 #include "imgui.h"
 #ifndef IMGUI_DISABLE
 #include "imgui_impl_wgpu.h"
@@ -245,7 +258,11 @@ static WGPUProgrammableStageDescriptor ImGui_ImplWGPU_CreateShaderModule(const c
     ImGui_ImplWGPU_Data* bd = ImGui_ImplWGPU_GetBackendData();
 
     WGPUShaderModuleWGSLDescriptor wgsl_desc = {};
+#ifdef IMGUI_IMPL_WEBGPU_BACKEND_DAWN
+    wgsl_desc.chain.sType = WGPUSType_ShaderSourceWGSL;
+#else
     wgsl_desc.chain.sType = WGPUSType_ShaderModuleWGSLDescriptor;
+#endif
     wgsl_desc.code = wgsl_source;
 
     WGPUShaderModuleDescriptor desc = {};
@@ -660,7 +677,11 @@ bool ImGui_ImplWGPU_CreateDeviceObjects()
     // Create depth-stencil State
     WGPUDepthStencilState depth_stencil_state = {};
     depth_stencil_state.format = bd->depthStencilFormat;
+#ifdef IMGUI_IMPL_WEBGPU_BACKEND_DAWN
+    depth_stencil_state.depthWriteEnabled = WGPUOptionalBool_False;
+#else
     depth_stencil_state.depthWriteEnabled = false;
+#endif
     depth_stencil_state.depthCompare = WGPUCompareFunction_Always;
     depth_stencil_state.stencilFront.compare = WGPUCompareFunction_Always;
     depth_stencil_state.stencilFront.failOp = WGPUStencilOperation_Keep;
@@ -730,7 +751,15 @@ 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(__EMSCRIPTEN__)
+    io.BackendRendererName = "imgui_impl_webgpu_emscripten";
+#elif defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN)
+    io.BackendRendererName = "imgui_impl_webgpu_dawn";
+#elif defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
+    io.BackendRendererName = "imgui_impl_webgpu_wgpu";
+#else
     io.BackendRendererName = "imgui_impl_webgpu";
+#endif
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
 
     bd->initInfo = *init_info;

diff --git a/backends/imgui_impl_wgpu.h b/backends/imgui_impl_wgpu.h
@@ -2,6 +2,13 @@
 // 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.)
 
+// 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.
+// 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.
+//#define IMGUI_IMPL_WEBGPU_BACKEND_DAWN
+//#define IMGUI_IMPL_WEBGPU_BACKEND_WGPU
+
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'WGPUTextureView' as ImTextureID. Read the FAQ about ImTextureID!
 //  [X] Renderer: Large meshes support (64k+ vertices) with 16-bit indices.

diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
@@ -77,6 +77,8 @@ Other changes:
 - Backends: SDL2: use SDL_Vulkan_GetDrawableSize() when available. (#7967, #3190) [@scribam]
 - Backends: GLFW+Emscripten: use OSX behaviors automatically when using contrib glfw port. (#7965, #7915)
   [@ypujante]
+- Backends: WebGPU: Added support for optional IMGUI_IMPL_WEBGPU_BACKEND_DAWN / IMGUI_IMPL_WEBGPU_BACKEND_WGPU
+  defines to handle ever-changing native implementations. (#7977, #7969, #6602, #6188, #7523) [@acgaudette]
 
 -----------------------------------------------------------------------
  VERSION 1.91.1 (Released 2024-09-04)

diff --git a/examples/example_glfw_wgpu/CMakeLists.txt b/examples/example_glfw_wgpu/CMakeLists.txt
@@ -79,6 +79,11 @@ add_executable(example_glfw_wgpu
   ${IMGUI_DIR}/imgui_tables.cpp
   ${IMGUI_DIR}/imgui_widgets.cpp
 )
+IF(NOT EMSCRIPTEN)
+  target_compile_definitions(example_glfw_wgpu PUBLIC
+    "IMGUI_IMPL_WEBGPU_BACKEND_DAWN"
+  )
+endif()
 target_include_directories(example_glfw_wgpu PUBLIC
   ${IMGUI_DIR}
   ${IMGUI_DIR}/backends