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[WebGPU] Update and Correct example and backend #8831

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d29a5f9
Update webgpu backend and example 1
manuel5975p Jul 23, 2025
f0640b8
Update example and Makefile
manuel5975p Jul 23, 2025
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Update webgpu backend and example 1
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@manuel5975p
manuel5975p committed Jul 23, 2025
commit d29a5f9fcfe27d5c5666ebb702bc5d3a1bc8445b
57 changes: 25 additions & 32 deletions backends/imgui_impl_wgpu.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -44,13 +44,14 @@
// 2021-01-28: Initial version.

#include "imgui.h"
#include <cstdlib>

// 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
//#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!
Expand Down Expand Up @@ -254,11 +255,11 @@ static void SafeRelease(FrameResources& res)
SafeRelease(res.VertexBufferHost);
}

static WGPUProgrammableStageDescriptor ImGui_ImplWGPU_CreateShaderModule(const char* wgsl_source)
static WGPUShaderModule ImGui_ImplWGPU_CreateShaderModule(const char* wgsl_source)
{
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_DAWN) || defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU) || defined(IMGUI_IMPLE_WEBGPU_BACKEND_WGVK)
WGPUShaderSourceWGSL wgsl_desc = {};
wgsl_desc.chain.sType = WGPUSType_ShaderSourceWGSL;
wgsl_desc.code = { wgsl_source, WGPU_STRLEN };
Expand All @@ -271,15 +272,7 @@ static WGPUProgrammableStageDescriptor ImGui_ImplWGPU_CreateShaderModule(const c
WGPUShaderModuleDescriptor desc = {};
desc.nextInChain = reinterpret_cast<WGPUChainedStruct*>(&wgsl_desc);

WGPUProgrammableStageDescriptor stage_desc = {};
stage_desc.module = wgpuDeviceCreateShaderModule(bd->wgpuDevice, &desc);

#if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) || defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
stage_desc.entryPoint = { "main", WGPU_STRLEN };
#else
stage_desc.entryPoint = "main";
#endif
return stage_desc;
return wgpuDeviceCreateShaderModule(bd->wgpuDevice, &desc);
}

static WGPUBindGroup ImGui_ImplWGPU_CreateImageBindGroup(WGPUBindGroupLayout layout, WGPUTextureView texture)
Expand Down Expand Up @@ -367,7 +360,7 @@ void ImGui_ImplWGPU_RenderDrawData(ImDrawData* draw_data, WGPURenderPassEncoder
// Avoid rendering when minimized
int fb_width = (int)(draw_data->DisplaySize.x * draw_data->FramebufferScale.x);
int fb_height = (int)(draw_data->DisplaySize.y * draw_data->FramebufferScale.y);
if (fb_width <= 0 || fb_height <= 0 || draw_data->CmdLists.Size == 0)
if (fb_width <= 0 || fb_height <= 0 || draw_data->CmdListsCount == 0)
return;

// Catch up with texture updates. Most of the times, the list will have 1 element with an OK status, aka nothing to do.
Expand Down Expand Up @@ -442,8 +435,9 @@ void ImGui_ImplWGPU_RenderDrawData(ImDrawData* draw_data, WGPURenderPassEncoder
// Upload vertex/index data into a single contiguous GPU buffer
ImDrawVert* vtx_dst = (ImDrawVert*)fr->VertexBufferHost;
ImDrawIdx* idx_dst = (ImDrawIdx*)fr->IndexBufferHost;
for (const ImDrawList* draw_list : draw_data->CmdLists)
for (int n = 0; n < draw_data->CmdListsCount; n++)
{
const ImDrawList* draw_list = draw_data->CmdLists[n];
memcpy(vtx_dst, draw_list->VtxBuffer.Data, draw_list->VtxBuffer.Size * sizeof(ImDrawVert));
memcpy(idx_dst, draw_list->IdxBuffer.Data, draw_list->IdxBuffer.Size * sizeof(ImDrawIdx));
vtx_dst += draw_list->VtxBuffer.Size;
Expand All @@ -470,8 +464,9 @@ void ImGui_ImplWGPU_RenderDrawData(ImDrawData* draw_data, WGPURenderPassEncoder
int global_idx_offset = 0;
ImVec2 clip_scale = draw_data->FramebufferScale;
ImVec2 clip_off = draw_data->DisplayPos;
for (const ImDrawList* draw_list : draw_data->CmdLists)
for (int n = 0; n < draw_data->CmdListsCount; n++)
{
const ImDrawList* draw_list = draw_data->CmdLists[n];
for (int cmd_i = 0; cmd_i < draw_list->CmdBuffer.Size; cmd_i++)
{
const ImDrawCmd* pcmd = &draw_list->CmdBuffer[cmd_i];
Expand Down Expand Up @@ -510,7 +505,7 @@ void ImGui_ImplWGPU_RenderDrawData(ImDrawData* draw_data, WGPURenderPassEncoder
continue;

// Apply scissor/clipping rectangle, Draw
wgpuRenderPassEncoderSetScissorRect(pass_encoder, (uint32_t)clip_min.x, (uint32_t)clip_min.y, (uint32_t)(clip_max.x - clip_min.x), (uint32_t)(clip_max.y - clip_min.y));
//wgpuRenderPassEncoderSetScissorRect(pass_encoder, (uint32_t)clip_min.x, (uint32_t)clip_min.y, (uint32_t)(clip_max.x - clip_min.x), (uint32_t)(clip_max.y - clip_min.y));
wgpuRenderPassEncoderDrawIndexed(pass_encoder, pcmd->ElemCount, 1, pcmd->IdxOffset + global_idx_offset, pcmd->VtxOffset + global_vtx_offset, 0);
}
}
Expand Down Expand Up @@ -560,11 +555,7 @@ void ImGui_ImplWGPU_UpdateTexture(ImTextureData* tex)

// Create texture
WGPUTextureDescriptor tex_desc = {};
#if defined(IMGUI_IMPL_WEBGPU_BACKEND_DAWN) || defined(IMGUI_IMPL_WEBGPU_BACKEND_WGPU)
tex_desc.label = { "Dear ImGui Texture", WGPU_STRLEN };
#else
tex_desc.label = "Dear ImGui Texture";
#endif
tex_desc.dimension = WGPUTextureDimension_2D;
tex_desc.size.width = tex->Width;
tex_desc.size.height = tex->Height;
Expand Down Expand Up @@ -696,9 +687,9 @@ bool ImGui_ImplWGPU_CreateDeviceObjects()
graphics_pipeline_desc.layout = wgpuDeviceCreatePipelineLayout(bd->wgpuDevice, &layout_desc);

// Create the vertex shader
WGPUProgrammableStageDescriptor vertex_shader_desc = ImGui_ImplWGPU_CreateShaderModule(__shader_vert_wgsl);
graphics_pipeline_desc.vertex.module = vertex_shader_desc.module;
graphics_pipeline_desc.vertex.entryPoint = vertex_shader_desc.entryPoint;
WGPUShaderModule vertex_shader_module = ImGui_ImplWGPU_CreateShaderModule(__shader_vert_wgsl);
graphics_pipeline_desc.vertex.module = vertex_shader_module;
graphics_pipeline_desc.vertex.entryPoint = WGPUStringView{"main", sizeof("main") - 1};

// Vertex input configuration
WGPUVertexAttribute attribute_desc[] =
Expand All @@ -724,7 +715,7 @@ bool ImGui_ImplWGPU_CreateDeviceObjects()
graphics_pipeline_desc.vertex.buffers = buffer_layouts;

// Create the pixel shader
WGPUProgrammableStageDescriptor pixel_shader_desc = ImGui_ImplWGPU_CreateShaderModule(__shader_frag_wgsl);
WGPUShaderModule pixel_shader_module = ImGui_ImplWGPU_CreateShaderModule(__shader_frag_wgsl);

// Create the blending setup
WGPUBlendState blend_state = {};
Expand All @@ -741,8 +732,8 @@ bool ImGui_ImplWGPU_CreateDeviceObjects()
color_state.writeMask = WGPUColorWriteMask_All;

WGPUFragmentState fragment_state = {};
fragment_state.module = pixel_shader_desc.module;
fragment_state.entryPoint = pixel_shader_desc.entryPoint;
fragment_state.module = pixel_shader_module;
fragment_state.entryPoint = WGPUStringView{"main", sizeof("main") - 1};
fragment_state.targetCount = 1;
fragment_state.targets = &color_state;

Expand Down Expand Up @@ -770,7 +761,9 @@ bool ImGui_ImplWGPU_CreateDeviceObjects()
graphics_pipeline_desc.depthStencil = (bd->depthStencilFormat == WGPUTextureFormat_Undefined) ? nullptr : &depth_stencil_state;

bd->pipelineState = wgpuDeviceCreateRenderPipeline(bd->wgpuDevice, &graphics_pipeline_desc);

if(bd->pipelineState == nullptr){
abort();
}
ImGui_ImplWGPU_CreateUniformBuffer();

// Create sampler
Expand Down Expand Up @@ -798,8 +791,8 @@ bool ImGui_ImplWGPU_CreateDeviceObjects()
bd->renderResources.CommonBindGroup = wgpuDeviceCreateBindGroup(bd->wgpuDevice, &common_bg_descriptor);
bd->renderResources.ImageBindGroupLayout = bg_layouts[1];

SafeRelease(vertex_shader_desc.module);
SafeRelease(pixel_shader_desc.module);
SafeRelease(vertex_shader_module);
SafeRelease(pixel_shader_module);
SafeRelease(graphics_pipeline_desc.layout);
SafeRelease(bg_layouts[0]);

Expand Down Expand Up @@ -905,4 +898,4 @@ void ImGui_ImplWGPU_NewFrame()

//-----------------------------------------------------------------------------

#endif // #ifndef IMGUI_DISABLE
#endif // #ifndef IMGUI_DISABLE
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