ifcviewer: visibility (hide/isolate/show-all) + X-ray — desktop parity on web

Lift the visibility + X-ray ops into ViewportCore so desktop and web share them.
The cull already reads visibility_ (hidden objects skipped) and the frame uniform
reads xray_alpha_cap_, both per frame, so each op just mutates state + schedules
a frame — no GPU buffers to rebuild, no rendering work:
- hideSelected (hide the selection, then deselect), isolateSelected (hide every
  non-selected object in a visible model), showAll (clear the hidden set),
  toggleXray (flip the alpha cap 1.0<->0.3; cull routes all to the transparent
  pass), xrayActive().
- Desktop ViewportWindow: the H / Shift+H / Alt+H / Alt+X keys and the menu-action
  wrappers now call the core; the four inline/duplicated implementations are gone.
- Web main_web: same keys (H hide · Shift+H isolate · Alt+H show all · Alt+X
  x-ray) + toolbar buttons (Hide / Isolate / Show all / X-ray, the last reflecting
  active state).

Verified on web: x-ray toggles and visibly translucent-izes the scene, hide after
a pick removes geometry, 0 GPU errors. 113/113 desktop + 6/6 web smoke; desktop
app builds.

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

src/ifcviewer-web/CMakeLists.txt

@@ -104,7 +104,7 @@ target_link_options(IfcViewerWeb PRIVATE
     # EMSCRIPTEN_KEEPALIVE alone keeps the symbols in the binary but doesn't
     # add them to Module. ccall lets shell.html pass a JS string (the ?model
     # URL) to load_sidecar_from_url_c without manual heap marshalling.
-    "-sEXPORTED_FUNCTIONS=['_main','_raf_tick_c','_load_sidecar_from_source_c','_clear_scene_c','_ifcv_on_range_done','_ifcv_chunks_resident_c','_ifcv_chunks_total_c','_ifcv_model_count_c','_ifcv_model_resident_c','_ifcv_model_total_c','_ifcv_bytes_total_c','_ifcv_bytes_needed_c','_ifcv_bytes_loaded_c','_view_all_c','_frame_selection_c','_toggle_projection_c','_projection_is_ortho_c','_standard_view_c','_toggle_fly_c','_fly_is_active_c']"
+    "-sEXPORTED_FUNCTIONS=['_main','_raf_tick_c','_load_sidecar_from_source_c','_clear_scene_c','_ifcv_on_range_done','_ifcv_chunks_resident_c','_ifcv_chunks_total_c','_ifcv_model_count_c','_ifcv_model_resident_c','_ifcv_model_total_c','_ifcv_bytes_total_c','_ifcv_bytes_needed_c','_ifcv_bytes_loaded_c','_view_all_c','_frame_selection_c','_toggle_projection_c','_projection_is_ortho_c','_standard_view_c','_toggle_fly_c','_fly_is_active_c','_hide_selected_c','_isolate_selected_c','_show_all_c','_toggle_xray_c','_xray_is_active_c']"
     # ccall: shell.html passes the ?model URL string to load_sidecar_from_url_c.
     # HEAPU8: lets tooling/tests read the wasm heap size (e.g. to verify a large
     # sidecar streams by range instead of loading whole). Standard, zero-cost.

src/ifcviewer-web/main_web.cpp

@@ -227,6 +227,16 @@ EM_BOOL onKeyDown(int, const EmscriptenKeyboardEvent* e, void* user) {
     // While flying, WASDQE/Shift are held-movement keys, not hotkeys.
     if (app->fly_mode) { if (setFlyKey(app, code, true)) return EM_TRUE; return EM_FALSE; }
     if (e->repeat) return EM_FALSE;
+    const bool alt = e->altKey;
+    // Visibility + X-ray, matching desktop: H hide selected · Shift+H isolate ·
+    // Alt+H show all · Alt+X x-ray.
+    if (!std::strcmp(code, "KeyH")) {
+        if      (alt)   app->core.showAll();
+        else if (shift) app->core.isolateSelected();
+        else            app->core.hideSelected();
+        return EM_TRUE;
+    }
+    if (!std::strcmp(code, "KeyX") && alt) { app->core.toggleXray(); return EM_TRUE; }
     using SV = ViewportCore::StandardView;
     if      (!std::strcmp(code, "Home"))            app->core.viewAll();
     else if (!std::strcmp(code, "KeyF") && !shift)  app->core.frameSelection();
@@ -356,6 +366,13 @@ extern "C" EMSCRIPTEN_KEEPALIVE int fly_is_active_c() {
     return (g_app && g_app->ready && g_app->fly_mode) ? 1 : 0;
 }
 
+// Visibility + X-ray, for the toolbar (same ops as the H/Shift+H/Alt+H/Alt+X keys).
+extern "C" EMSCRIPTEN_KEEPALIVE void hide_selected_c()    { if (g_app && g_app->ready) g_app->core.hideSelected(); }
+extern "C" EMSCRIPTEN_KEEPALIVE void isolate_selected_c() { if (g_app && g_app->ready) g_app->core.isolateSelected(); }
+extern "C" EMSCRIPTEN_KEEPALIVE void show_all_c()         { if (g_app && g_app->ready) g_app->core.showAll(); }
+extern "C" EMSCRIPTEN_KEEPALIVE void toggle_xray_c()      { if (g_app && g_app->ready) g_app->core.toggleXray(); }
+extern "C" EMSCRIPTEN_KEEPALIVE int  xray_is_active_c()   { return (g_app && g_app->ready && g_app->core.xrayActive()) ? 1 : 0; }
+
 // id: 0 Front, 1 Back, 2 Left, 3 Right, 4 Top, 5 Bottom.
 extern "C" EMSCRIPTEN_KEEPALIVE void standard_view_c(int id) {
     if (!g_app || !g_app->ready || id < 0 || id > 5) return;

src/ifcviewer-web/shell.html

@@ -86,6 +86,11 @@
   <button data-view="3" title="Right (Y)">Right</button>
   <button data-view="4" title="Top (Z)">Top</button>
   <button data-view="5" title="Bottom (Shift+Z)">Bottom</button>
+  <span class="sep"></span>
+  <button data-act="hide"    title="Hide selected (H)">Hide</button>
+  <button data-act="isolate" title="Isolate selected (Shift+H)">Isolate</button>
+  <button data-act="showall" title="Show all (Alt+H)">Show all</button>
+  <button data-act="xray"    id="xray-btn" title="X-ray — translucent everything (Alt+X)">X-ray</button>
 </div>
 <div id="status">Starting…</div>
 <script>
@@ -162,6 +167,10 @@
             var fb = document.getElementById('fly-btn');
             if (fb) fb.classList.toggle('active', !!Module._fly_is_active_c());
           }
+          if (Module._xray_is_active_c) {
+            var xb = document.getElementById('xray-btn');
+            if (xb) xb.classList.toggle('active', !!Module._xray_is_active_c());
+          }
           Module._raf_tick_c(Module._app_ptr);
         }
         requestAnimationFrame(shellTick);
@@ -338,6 +347,10 @@
       else if (act === 'focus') Module._frame_selection_c();
       else if (act === 'ortho') { Module._toggle_projection_c(); refreshOrthoLabel(); }
       else if (act === 'fly')   Module._toggle_fly_c();
+      else if (act === 'hide')    Module._hide_selected_c();
+      else if (act === 'isolate') Module._isolate_selected_c();
+      else if (act === 'showall') Module._show_all_c();
+      else if (act === 'xray')    Module._toggle_xray_c();
       else if (view !== null)   Module._standard_view_c(parseInt(view, 10));
     });
   });