wgpu backend: --camera flag + request adapter's max buffer limits

Two pieces that block proper side-by-side parity with the GL minimal:

1. --camera tx,ty,tz,dist,yaw,pitch. Same format string as the GL
   minimal so a pasted camera arg lands the same view on both backends.
   setCamera() also flips initial_view_applied_ = true so the auto-
   viewAll-on-first-load doesn't snap away from the script-set position
   when the model finishes uploading.

2. Real BIM models exceed the conservative WebGPU defaults at device
   create time. A 114k-instance / 19M-index sidecar's vertex storage is
   139 MB, which trips wgpu's default 128 MB max_storage_buffer_binding_
   size and bind-group creation fails. Now wgpuAdapterGetLimits is
   called first and the device is requested at the adapter's full
   ceiling — every desktop driver supports multi-GB.

   Trade-off worth flagging: web parity will fail here because browsers
   cap at the defaults. The eventual fix is to split a model's vertex/
   instance storage into ≤128 MB chunks with a small per-frame routing
   table, which is a real chunk of work. For now this unblocks all the
   native benchmarking the user is actually doing.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/ifcviewer-wgpu-minimal/main.cpp

@@ -45,6 +45,9 @@ int main(int argc, char* argv[]) {
         "Render one frame, save to PATH as PNG, exit.", "path"});
     parser.addOption({{"b", "benchmark"},
         "Render N frames (yaw-sweeping the camera), print stats, exit.", "frames"});
+    parser.addOption({{"c", "camera"},
+        "Set camera as tx,ty,tz,dist,yaw,pitch (same format as IfcViewerMinimal).",
+        "params"});
     parser.process(app);
 
     auto* viewport = new WgpuViewportWindow;
@@ -65,6 +68,23 @@ int main(int argc, char* argv[]) {
         viewport->queueLoadSidecar(path);
     }
 
+    if (parser.isSet("camera")) {
+        const QStringList parts = parser.value("camera").split(',');
+        if (parts.size() == 6) {
+            bool ok = true;
+            float v[6];
+            for (int i = 0; i < 6 && ok; ++i) v[i] = parts[i].toFloat(&ok);
+            if (ok) {
+                viewport->setCamera(v[0], v[1], v[2], v[3], v[4], v[5]);
+            } else {
+                qWarning() << "--camera: failed to parse" << parser.value("camera");
+            }
+        } else {
+            qWarning() << "--camera: expected 6 comma-separated floats, got"
+                       << parts.size();
+        }
+    }
+
     if (parser.isSet("screenshot")) {
         viewport->captureNextFrameToPng(parser.value("screenshot"),
                                         /*quit_after=*/true);

src/ifcviewer-wgpu/WgpuViewportWindow.cpp

@@ -631,7 +631,19 @@ bool WgpuViewportWindow::initWgpu() {
     struct DeviceReq { WGPUDevice device = nullptr; bool done = false; bool ok = false; };
     DeviceReq dreq;
 
+    // Query what the adapter can do, and request the same headroom on the
+    // device so a single large model's vertex/instance storage buffer doesn't
+    // hit the conservative defaults (128 MB binding, 256 MB buffer). Real
+    // BIM models routinely cross 100 MB of vertex bytes; without this the
+    // first applyCachedModel fails with a bind-group validation error.
+    //
+    // For eventual web parity this needs revisiting — browsers cap at the
+    // defaults — but native targets always support the requested ceilings.
+    WGPULimits adapter_limits = {};
+    wgpuAdapterGetLimits(adapter_, &adapter_limits);
+
     WGPUDeviceDescriptor dev_desc = {};
+    dev_desc.requiredLimits = &adapter_limits;
     // Surface uncaptured errors (validation failures etc.) into qWarning so
     // they're attributable rather than silently swallowed.
     dev_desc.uncapturedErrorCallbackInfo.callback = onUncapturedError;
@@ -1543,6 +1555,20 @@ bool WgpuViewportWindow::computeSceneAabb(float mn[3], float mx[3]) const {
     return any;
 }
 
+void WgpuViewportWindow::setCamera(float tx, float ty, float tz,
+                                   float dist, float yaw_deg, float pitch_deg) {
+    camera_target_[0] = tx;
+    camera_target_[1] = ty;
+    camera_target_[2] = tz;
+    camera_distance_  = std::max(0.01f, dist);
+    camera_yaw_deg_   = yaw_deg;
+    camera_pitch_deg_ = std::clamp(pitch_deg, -89.9f, 89.9f);
+    // Suppress the auto-viewAll on the first model load so the script-set
+    // camera survives. Manual viewAll() calls after this still work.
+    initial_view_applied_ = true;
+    if (isExposed()) requestUpdate();
+}
+
 void WgpuViewportWindow::viewAll() {
     float mn[3], mx[3];
     if (!computeSceneAabb(mn, mx)) return;

src/ifcviewer-wgpu/WgpuViewportWindow.h

@@ -72,10 +72,17 @@ public:
     size_t modelCount() const { return models_gpu_.size(); }
 
     // Frame the union of all loaded models' world AABBs. No-op on empty
-    // scenes. Called automatically after the first model loads; clients
-    // can re-invoke to re-frame.
+    // scenes. Called automatically after the first model loads (unless
+    // setCamera was already invoked); clients can re-invoke to re-frame.
     void viewAll();
 
+    // Explicit camera state, mirroring the GL ViewportWindow API. Suppresses
+    // the auto-viewAll on first load so a script-driven camera survives
+    // model loading. Parameters match the GL --camera tx,ty,tz,dist,yaw,pitch
+    // order so a pasted camera string lands the same view in both backends.
+    void setCamera(float tx, float ty, float tz,
+                   float dist, float yaw_deg, float pitch_deg);
+
     // Queue a one-shot framebuffer capture: the next rendered frame is
     // copied back to host memory and saved to `path` as PNG. If
     // `quit_after` is true, QCoreApplication::quit() is called once the