Replaces the standalone wgpu-only clear-color spike in main_web.cpp
with a real WebViewportHost implementation: surface creation via the
emdawnwebgpu canvas-selector source, framebufferSize through
emscripten_get_element_css_size + dpr, requestFrame as a deferred
flag the RAF main_loop consumes, quit through emscripten_force_exit.
main_web.cpp now does the same lifecycle the desktop initWgpu shell
does: core_.initWgpu(web_limits=true) → buildPipelines → buildHiz/
Edge/Pick. The render loop runs core_.render() once per RAF tick when
the host has flagged a frame pending, with a surface reconfigure on
size changes.
Builds clean under emcc 6.0 + emdawnwebgpu (1.4 MB wasm, 278 KB JS
glue). Renders an empty scene with the configured background — the
plumbing is end-to-end through the same ViewportCore code path the
desktop build uses. No sidecar load yet: that lands with the
emscripten_fetch streaming backend (#88).
First Emscripten target. main_web.cpp brings up a wgpu instance against
a <canvas id="viewer-canvas">, requests adapter+device asynchronously
via the standard webgpu.h callback chain, configures the surface, and
clears to the BonsaiViewer slate background on each RAF tick. No
sidecar load, no pipelines, no scene state yet — the goal is to end-
to-end verify the build + canvas + wgpu plumbing.
src/ifcviewer-web/ is a separate CMake root (not a subdir under the
desktop cmake/CMakeLists.txt) so the web build doesn't have to opt out
of Qt / OpenCASCADE / IfcGeom find_packages it can't satisfy. It adds
src/ifcviewer EXCLUDE_FROM_ALL and consumes only IfcViewerCore.
src/ifcviewer/CMakeLists.txt now gates the wgpu-native fetch + the
Qt-using IfcViewer target + install commands behind NOT EMSCRIPTEN.
The wgpu_native link target still resolves under Emscripten as an
INTERFACE library that activates --use-port=emdawnwebgpu (Dawn's
webgpu.h, replaces the legacy -sUSE_WEBGPU=1).
Build:
source path/to/emsdk_env.sh
emcmake cmake -S src/ifcviewer-web -B build-web -G Ninja
ninja -C build-web
python3 -m http.server --directory build-web 8080
# open http://localhost:8080/IfcViewerWeb.html in a WebGPU-capable
# browser (Chrome 113+, Edge 113+).
Phase B step 3 of #45.
Dion Moult