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/widgets/log_panel.py

@@ -2,7 +2,7 @@
 
 from __future__ import annotations
 
-from PyQt5.QtGui import QFont
+from PyQt5.QtGui import QFont, QTextCursor
 from PyQt5.QtWidgets import QPlainTextEdit
 
 
@@ -22,30 +22,68 @@ class TeeStream:
 
 
 class WidgetLogHandler:
-    """Mirror print output into a QPlainTextEdit."""
+    """Mirror print output into a QPlainTextEdit with a live status line at the bottom."""
 
     def __init__(self, widget: QPlainTextEdit):
         self.widget = widget
         self.buf = ""
+        self._has_status_line = False
 
     def write(self, text: str):
         self.buf += text
         while "\n" in self.buf:
             line, self.buf = self.buf.split("\n", 1)
             if line:
-                self.widget.appendPlainText(line)
+                self._append_log_line(line)
 
     def flush(self):
         if self.buf:
-            self.widget.appendPlainText(self.buf)
+            self._append_log_line(self.buf)
             self.buf = ""
 
+    def set_status_line(self, text: str) -> None:
+        """Update the pinned bottom line (FPS / forces) without scrolling the log."""
+        text = text.rstrip("\n")
+        if self._has_status_line:
+            cursor = QTextCursor(self.widget.document().lastBlock())
+            cursor.select(QTextCursor.BlockUnderCursor)
+            cursor.insertText(text)
+        else:
+            self.widget.appendPlainText(text)
+            self._has_status_line = True
+        scrollbar = self.widget.verticalScrollBar()
+        scrollbar.setValue(scrollbar.maximum())
 
-def make_log_widget() -> QPlainTextEdit:
+    def clear_status_line(self) -> None:
+        if not self._has_status_line:
+            return
+        cursor = QTextCursor(self.widget.document().lastBlock())
+        cursor.select(QTextCursor.BlockUnderCursor)
+        cursor.removeSelectedText()
+        self._has_status_line = False
+
+    def _append_log_line(self, line: str) -> None:
+        status = None
+        if self._has_status_line:
+            status = self.widget.document().lastBlock().text()
+            cursor = QTextCursor(self.widget.document().lastBlock())
+            cursor.select(QTextCursor.BlockUnderCursor)
+            cursor.removeSelectedText()
+            self._has_status_line = False
+        self.widget.appendPlainText(line)
+        if status is not None:
+            self.set_status_line(status)
+
+
+def make_log_widget(config=None) -> QPlainTextEdit:
+    if config is None:
+        from ..layout import LOG_CONFIG
+
+        config = LOG_CONFIG
     widget = QPlainTextEdit()
     widget.setReadOnly(True)
-    widget.setMaximumBlockCount(2000)
-    font = QFont("Consolas", 12)
+    widget.setMaximumBlockCount(config.max_lines)
+    font = QFont(config.font_family, config.font_pt)
     font.setStyleHint(QFont.Monospace)
     widget.setFont(font)
     return widget