1. tuned arrow mesh drawing

2. centralixzed arrow config in layout.py
3. seperate mesh render and display resolution to speed up (~40 fps)

examples/gui/mesh_render_worker.py

@@ -0,0 +1,74 @@
+"""Background Open3D mesh rendering for the Qt dashboard."""
+
+from __future__ import annotations
+
+import numpy as np
+from PyQt5.QtCore import QMutex, QMutexLocker, QThread, pyqtSignal
+
+
+class MeshRenderWorker(QThread):
+    """Render finger mesh off the GUI thread; drops stale frames."""
+
+    rgb_ready = pyqtSignal(object)
+
+    def __init__(self, parent=None):
+        super().__init__(parent)
+        self._mutex = QMutex()
+        self._stop = False
+        self._wake = False
+        self._renderer = None
+        self._pending: dict | None = None
+
+    def set_renderer(self, renderer) -> None:
+        with QMutexLocker(self._mutex):
+            self._renderer = renderer
+
+    def clear_renderer(self) -> None:
+        with QMutexLocker(self._mutex):
+            self._renderer = None
+            self._pending = None
+
+    def submit(self, *, flow, scalar_map, centroid, centroid_found, fnormal) -> None:
+        with QMutexLocker(self._mutex):
+            self._pending = {
+                "flow": flow,
+                "scalar_map": scalar_map,
+                "centroid": centroid,
+                "centroid_found": centroid_found,
+                "fnormal": fnormal,
+            }
+            self._wake = True
+        if not self.isRunning():
+            self.start()
+
+    def stop_worker(self) -> None:
+        with QMutexLocker(self._mutex):
+            self._stop = True
+            self._wake = True
+        self.wait(2000)
+
+    def run(self) -> None:
+        while True:
+            with QMutexLocker(self._mutex):
+                if self._stop:
+                    break
+                if not self._wake or self._renderer is None or self._pending is None:
+                    self.msleep(1)
+                    continue
+                job = self._pending
+                self._pending = None
+                self._wake = False
+                renderer = self._renderer
+
+            rgb = renderer.render(
+                flow=job["flow"],
+                scalar_map=job["scalar_map"],
+                centroid=job["centroid"],
+                centroid_found=job["centroid_found"],
+                fnormal=job["fnormal"],
+            )
+            self.rgb_ready.emit(np.ascontiguousarray(rgb))
+
+            with QMutexLocker(self._mutex):
+                if self._pending is not None:
+                    self._wake = True