ifcviewer-web: load user sidecars via a file-browse button (#46)

Adds an "Open .ifcview…" button that opens the browser's native file
chooser. The picked file's bytes are written into MEMFS and a new
exported entry point, load_uploaded_model_c, reads them back via the
existing loadSidecarFromPath: it resetScene()s the current model
(replace, not append), loads the sidecar, and viewAll()s it. Geometry
becomes resident over subsequent frames through render()'s inline
driveStreamingLoads, same as the embedded sample.

Deliberately a file picker, not drag-drop: browser file drag-drop needs
an X11 drag source (a file manager) to drag *from*, which a minimal WM
(ratpoison) doesn't provide. The native chooser is WM-independent.

Exports _load_uploaded_model_c and the FS runtime method; URL/byte-range
fetch of remote models stays for #88.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/ifcviewer-web/CMakeLists.txt

@@ -96,10 +96,17 @@ target_link_options(IfcViewerWeb PRIVATE
     # main() to set noExitRuntime as a side effect — registers a RAF
     # that starves the device promise (observed: ~10s delay in Firefox).
     "-sEXIT_RUNTIME=0"
-    # Expose the C tick entry point to JS so shell.html's RAF loop
-    # can call Module._raf_tick_c. EMSCRIPTEN_KEEPALIVE alone keeps
-    # the symbol in the binary but doesn't add it to Module.
-    "-sEXPORTED_FUNCTIONS=['_main','_raf_tick_c']"
+    # Expose the C entry points to JS. _raf_tick_c drives the RAF loop
+    # (shell.html); _load_uploaded_model_c loads a user-picked sidecar
+    # that JS has written into MEMFS. EMSCRIPTEN_KEEPALIVE alone keeps
+    # the symbols in the binary but doesn't add them to Module.
+    "-sEXPORTED_FUNCTIONS=['_main','_raf_tick_c','_load_uploaded_model_c']"
+    # FS lets shell.html's file-browse handler write the picked file's
+    # bytes into MEMFS before calling _load_uploaded_model_c (which
+    # fopen()s the virtual path). Drag-drop is intentionally not used —
+    # it depends on an X11 drag source (file manager), which a minimal
+    # WM may not provide; the native file chooser is WM-independent.
+    "-sEXPORTED_RUNTIME_METHODS=['FS']"
     # Streaming + chunked geometry want a heap that can grow as buffers
     # arrive. 256 MB initial, 2 GB ceiling (matches the wasm32 pointer
     # cap; --shared64 / MEMORY64 would lift this later if we need it).

src/ifcviewer-web/main_web.cpp

@@ -41,6 +41,10 @@ namespace {
 // WebViewportHost selector below.
 constexpr const char* kCanvasSelector = "#viewer-canvas";
 
+// MEMFS path the file-browse handler writes the picked sidecar to, and
+// that load_uploaded_model_c reads back. Must match shell.html.
+constexpr const char* kUploadPath = "/uploads/model.ifcview";
+
 struct AppState {
     WebViewportHost host{ kCanvasSelector };
     ViewportCore    core{ &host };
@@ -152,6 +156,28 @@ extern "C" EMSCRIPTEN_KEEPALIVE void raf_tick_c(void* user) {
     }
 }
 
+// Called from shell.html's file-browse handler after it has written the
+// picked file's bytes into MEMFS at kUploadPath. Replaces whatever is
+// currently loaded (the embedded sample on first use, or a prior upload)
+// with the new sidecar and frames it. Geometry becomes resident over the
+// next frames via render()'s inline driveStreamingLoads. Exported to JS
+// via EXPORTED_FUNCTIONS in CMakeLists.txt.
+extern "C" EMSCRIPTEN_KEEPALIVE void load_uploaded_model_c() {
+    if (!g_app || !g_app->ready) return;
+
+    // resetScene drops the previous model's GPU resources so a fresh load
+    // replaces rather than accumulates (loadSidecarFromPath appends).
+    g_app->core.resetScene();
+    const unsigned int mid = g_app->core.loadSidecarFromPath(kUploadPath);
+    if (mid == 0) {
+        Log::warn() << "ifcviewer-web: uploaded model load failed";
+        return;
+    }
+    g_app->core.viewAll();
+    g_app->host.requestFrame();
+    Log::info() << "ifcviewer-web: loaded uploaded model (id " << mid << ")";
+}
+
 int main(int /*argc*/, char** /*argv*/) {
     Log::info() << "ifcviewer-web: starting";
     g_app = new AppState();

src/ifcviewer-web/shell.html

@@ -14,10 +14,17 @@
     background: rgba(20,22,28,.78); padding: 6px 10px; border-radius: 4px;
     white-space: pre-wrap; pointer-events: auto; }
   #status.error { background: rgba(120,30,30,.85); color: #fff; }
+  #open-btn { position: fixed; top: 8px; right: 12px; z-index: 10;
+    background: #2b6cb0; color: #fff; border: none; padding: 6px 12px;
+    border-radius: 4px; font-size: 12px; cursor: pointer; }
+  #open-btn:hover { background: #3182ce; }
+  #file-input { display: none; }
 </style>
 </head>
 <body>
 <canvas id="viewer-canvas" width="1280" height="800"></canvas>
+<button id="open-btn">Open .ifcview…</button>
+<input id="file-input" type="file" accept=".ifcview">
 <div id="status">Starting…</div>
 <script>
   // Emscripten Module hook: route stderr to the status overlay so any
@@ -69,6 +76,37 @@
     statusEl.textContent = 'navigator.gpu is missing — open in a browser with WebGPU enabled';
     statusEl.classList.add('error');
   }
+
+  // File-browse loading. The picked file's bytes are written into MEMFS
+  // (the same virtual FS the wasm fopen()s) and then load_uploaded_model_c
+  // is invoked to read + render it. No drag-drop: that needs an X11 drag
+  // source (a file manager), which a minimal WM may not provide; the
+  // native file chooser this button opens is WM-independent.
+  var openBtn = document.getElementById('open-btn');
+  var fileInput = document.getElementById('file-input');
+  openBtn.addEventListener('click', function() { fileInput.click(); });
+  fileInput.addEventListener('change', function(ev) {
+    var f = ev.target.files && ev.target.files[0];
+    if (!f) return;
+    if (!Module.FS || !Module._load_uploaded_model_c) {
+      statusEl.textContent += 'viewer not ready yet — wait for WebGPU init\n';
+      return;
+    }
+    var reader = new FileReader();
+    reader.onload = function() {
+      try {
+        var bytes = new Uint8Array(reader.result);
+        try { Module.FS.mkdir('/uploads'); } catch (e) { /* already exists */ }
+        Module.FS.writeFile('/uploads/model.ifcview', bytes);
+        Module._load_uploaded_model_c();
+      } catch (e) {
+        statusEl.textContent += 'load failed: ' + e + '\n';
+        statusEl.classList.add('error');
+      }
+      fileInput.value = '';  // let the same file be re-picked
+    };
+    reader.readAsArrayBuffer(f);
+  });
 </script>
 <!-- IfcViewerWeb.js is emitted alongside this shell by the emcc build;
      `--shell-file` injects this HTML around it. -->