try to fix wsl open3d crash

examples/gui/widgets/mesh_viewport.py

@@ -2,8 +2,6 @@
 
 from __future__ import annotations
 
-import sys
-
 from PyQt5.QtCore import QEvent, Qt
 from PyQt5.QtGui import QMouseEvent
 
@@ -105,10 +103,6 @@ class MeshViewportWidget(ImagePanel):
             return
         self.label.setText("")
         self._init_renderer(pipeline)
-        if self._layout.mesh_async_render and sys.platform != "win32":
-            self._mesh_worker = MeshRenderWorker(self)
-            self._mesh_worker.rgb_ready.connect(self._on_rgb_ready)
-            self._mesh_worker.set_renderer(self._renderer)
 
     def _init_renderer(self, pipeline) -> None:
         if not self._enable_3d or pipeline.uv_mesh is None:
@@ -156,22 +150,12 @@ class MeshViewportWidget(ImagePanel):
         self.set_source_pixmap(ndarray_to_pixmap(rgb, bgr=False))
 
     def update_frame(self, frame: FingerFrameView, *, async_render: bool | None = None) -> float:
-        """Update mesh colors. Returns render wall time (0 when async submit only)."""
+        """Update mesh colors on the same thread that owns the renderer."""
         if not self._enable_3d or self._renderer is None:
             return 0.0
 
         self._last_frame = frame
-        use_async = self._layout.mesh_async_render if async_render is None else async_render
-        if use_async and self._mesh_worker is not None:
-            self._mesh_worker.submit(
-                flow=frame.flow,
-                scalar_map=frame.depth_map,
-                centroid=frame.centroid,
-                centroid_found=frame.centroid_found,
-                fnormal=frame.fnormal,
-                valid_mask=frame.valid_mask,
-            )
-            return 0.0
+        del async_render  # Offscreen Open3D renderers are not safe to drive from a QThread.
 
         import time