readme update

README.md

@@ -1,35 +1,78 @@
 # Crafter.Graphics
 
-Vulkan-based graphics library built around C++20 modules and the bindless
-`VK_EXT_descriptor_heap` extension. Provides window management, ray
-tracing, and a compute-shader-driven UI on a single, opinionated stack.
+Vulkan + WebGPU graphics library built around C++20 modules and
+bindless heaps. Provides window management, ray tracing, and a
+compute-shader-driven UI on a single, opinionated stack. Native
+builds use Vulkan with `VK_EXT_descriptor_heap`; `wasm32-*` builds
+target the browser via WebGPU and a DOM window backend.
+
+## Backends
+
+Backends are chosen at build time by the target triple:
+
+| Target              | Window                 | Renderer            | Shaders |
+|---------------------|------------------------|---------------------|---------|
+| native Linux        | Wayland                | Vulkan (heap-bound) | GLSL → SPIR-V |
+| native Windows      | Win32                  | Vulkan (heap-bound) | GLSL → SPIR-V |
+| `wasm32-*` (any)    | DOM (canvas + JS env)  | WebGPU              | WGSL (loaded at runtime) |
+
+The two backends share the same C++ surface for the high-level pieces
+(`UIRenderer`, `Mesh`, `RenderingElement3D`, `RTPass`, item structs,
+`FontAtlas`, `Image2D`, `ComputeShader`). Backend-typed pieces
+(`*Vulkan` vs `*WebGPU`) live behind `#ifdef CRAFTER_GRAPHICS_WINDOW_DOM`.
+Vulkan ray tracing is hardware (`VK_KHR_ray_tracing_pipeline`); WebGPU
+ray tracing is a library-built software path (BVH + traceRay in a
+compute pipeline composed from user-supplied WGSL stages).
 
 ## What's in here
 
-- **Window** — Wayland and Win32 backends, swapchain ring, frame pacing,
-  input events. Pick a backend at build time via the target triple.
-- **Device** — single-Vulkan-instance bring-up. The library targets
-  `VK_EXT_descriptor_heap` exclusively; pipelines are created with
+- **Window** — Wayland, Win32, and DOM backends, swapchain ring / canvas
+  framing, input events. Pick a backend at build time via the target
+  triple. The DOM backend routes every dynamic symbol through
+  [additional/dom-env.js](additional/dom-env.js) and
+  [additional/dom-webgpu.js](additional/dom-webgpu.js).
+- **Device** *(Vulkan only)* — single-instance bring-up targeting
+  `VK_EXT_descriptor_heap`; pipelines are created with
   `VK_PIPELINE_CREATE_2_DESCRIPTOR_HEAP_BIT_EXT` so there are no
   descriptor-set layouts and push constants travel via
   `vkCmdPushDataEXT`.
-- **DescriptorHeapVulkan** — bindless slot allocator. `AllocateImageSlots`
-  / `AllocateBufferSlots` / `AllocateSamplerSlots`, with byte-offset
-  helpers for direct descriptor writes.
-- **VulkanBuffer\<T, Mapped\>** — typed buffer with optional host mapping
-  and a `FlushDevice` that issues the right host-write barrier.
-- **ImageVulkan\<Pixel\>** — image + staging buffer, mip-chain support,
-  one-shot uploads via a command buffer.
-- **PipelineRTVulkan / ShaderBindingTableVulkan / RTPass** — ray-tracing
-  pipeline, SBT, and a `RenderPass` that dispatches it.
-- **ComputeShader** — the Tier 1 wrapper used by the UI system. Loads a
-  `.spv`, builds a heap-bound compute pipeline, dispatches with
-  `vkCmdPushDataEXT`. Use it directly for any custom compute.
-- **UI** — three-tier UI system; see below.
+- **DescriptorHeapVulkan / DescriptorHeapWebGPU** — bindless slot
+  allocators. Vulkan side allocates image/buffer/sampler slots in a
+  `VK_EXT_descriptor_heap`; WebGPU side resolves slots to JS-side
+  handle-table cookies that the dispatch bridge binds per pass.
+- **VulkanBuffer\<T, Mapped\> / WebGPUBuffer\<T\>** — typed buffer.
+  Vulkan variant has optional host mapping and a `FlushDevice` that
+  issues the right host-write barrier; WebGPU variant goes through
+  `queue.writeBuffer` over the JS bridge.
+- **ImageVulkan\<Pixel\> / Image2D\<Pixel\> / Image2DArray\<Pixel\>** —
+  image + staging buffer with mip-chain support on Vulkan; on WebGPU,
+  `rgba8unorm` 2D / 2D-array textures created and written via the
+  bridge. Atlas (`r8unorm`, sub-region writes) is a separate path.
+- **PipelineRTVulkan / PipelineRTWebGPU / ShaderBindingTableVulkan /
+  ShaderBindingTableWebGPU / RTPass** — ray-tracing pipelines. Vulkan
+  uses native RT pipelines + SBTs; WebGPU composes one compute
+  pipeline by stitching the traversal library, a generated hit-group
+  switch, and the user's raygen / closesthit / miss / anyhit WGSL.
+- **ComputeShader / WebGPUComputeShader** — Tier 1 wrapper used by the
+  UI system. Vulkan loads a `.spv` and dispatches with
+  `vkCmdPushDataEXT`; WebGPU loads a user-supplied `.wgsl` blob at
+  runtime via `wgpuLoadCustomShader`. Use it directly for any custom
+  compute.
+- **UI** — three-tier UI system; see below. The standard shaders ship
+  as four `.spv` blobs on native and four WGSL strings baked into the
+  WebGPU dispatcher.
 - **FontAtlas** — single-channel SDF atlas (1024×1024, 32pt base,
   shelf-packed, lazy `Ensure` per codepoint, dirty-flush via `Update`).
+  Backend-agnostic.
 - **Mesh / RenderingElement3D / Animation** — BLAS/TLAS construction
-  and 3D scene plumbing for the ray-tracing path.
+  and 3D scene plumbing. Vulkan calls `vkCmdBuildAccelerationStructures`;
+  WebGPU registers BLAS data (verts, idx, BVH nodes, primRemap, optional
+  per-vertex attribs) into global mesh heaps and builds the TLAS in a
+  library compute pass.
+- **Clipboard / Input / Gamepad / Router / Dom** — input plumbing.
+  Gamepad uses libudev+libevdev on Linux and WGI on Windows; the DOM
+  backend exposes the host page DOM (`Dom::HtmlElement`) and a router
+  for hash-routed wasm apps.
 
 ## UI system (three tiers)
 
@@ -78,27 +121,47 @@ The repository is built with `crafter-build` (a project-config based
 build system; the project description lives in `project.cpp`):
 
 ```bash
-crafter-build           # build the library
+crafter-build                        # native: Wayland on Linux, Win32 on Windows
+crafter-build --target=wasm32-wasip1 # browser: DOM window + WebGPU renderer
 crafter-build -r                     # build and run (in an example directory)
 ```
 
-The build picks the window backend automatically: Wayland on Linux,
-Win32 on Windows / mingw. Cross-compile via the standard `--target=...`
-flag.
+The build picks the window + renderer pair automatically from the
+target triple: any `wasm32-*` triple flips to DOM + WebGPU (no Vulkan
+loader linked), everything else stays on the native Vulkan path. Each
+example with both backends ships GLSL *and* WGSL copies of its shaders
+side-by-side (e.g. [raygen.glsl](examples/Sponza/raygen.glsl) +
+[raygen.wgsl](examples/Sponza/raygen.wgsl)); `project.cpp` selects the
+right set per target.
 
 ## Examples
 
 See [examples/](examples/). Quick map:
 
-- [HelloWindow](examples/HelloWindow/) — minimal window, no rendering.
-- [VulkanTriangle](examples/VulkanTriangle/) — ray-traced triangle, the
-  smallest test of the bindless + ray-tracing path.
+- [HelloWindow](examples/HelloWindow/) — minimal native window, no rendering.
+- [HelloDom](examples/HelloDom/) — wasm-only smoke test of the DOM
+  partition: page-level events, `HtmlElement::CreateInBody`, and
+  `Router::PushState`-driven SPA navigation. No GPU work.
+- [VulkanTriangle](examples/VulkanTriangle/) — ray-traced triangle on
+  both Vulkan and WebGPU. The smallest test of the bindless + RT path
+  on each backend.
+- [Sponza](examples/Sponza/) — ray-traced Sponza atrium on both
+  backends. Exercises `.cmesh` / `.ctex` decompression (GPU
+  `VK_EXT_memory_decompression` on Vulkan, CPU on WebGPU) and a
+  textured closest-hit. See [its README](examples/Sponza/README.md)
+  for asset provenance.
 - [HelloUI](examples/HelloUI/) — UI smoke test using all three tiers
   (background quad, slider, progress bar, button with text label,
   cursor-tracking circle).
 - [CustomShader](examples/CustomShader/) — Tier 1 demo: a user-authored
   compute shader inverting RGB under a list of item-circles, dispatched
-  alongside the standard `drawQuads`. The "could attempt #2 do this?" test.
+  alongside the standard `drawQuads`. Shipped as both
+  [`.comp.glsl`](examples/CustomShader/inverse-circle.comp.glsl) and
+  [`.comp.wgsl`](examples/CustomShader/inverse-circle.comp.wgsl).
+- [Decompression](examples/Decompression/) — `Crafter::Compression`
+  CPU round-trip smoke test (used by the WebGPU asset path).
+- [InputSystem](examples/InputSystem/) — keyboard / mouse / gamepad
+  event surface check.
 
 ## License