From c0c5eeb27e447df7eee9a98277d88c5cca252180 Mon Sep 17 00:00:00 2001
From: rdb <git@rdb.name>
Date: Fri, 18 Feb 2022 17:23:30 +0100
Subject: [PATCH] display: Don't start/stop collectors for empty window list

---
 panda/src/display/graphicsEngine.cxx | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/panda/src/display/graphicsEngine.cxx b/panda/src/display/graphicsEngine.cxx
index bc98317a01..ec047a8ac0 100644
--- a/panda/src/display/graphicsEngine.cxx
+++ b/panda/src/display/graphicsEngine.cxx
@@ -2579,10 +2579,18 @@ void GraphicsEngine::WindowRenderer::
 do_frame(GraphicsEngine *engine, Thread *current_thread) {
   LightReMutexHolder holder(_wl_lock);
 
-  engine->cull_to_bins(_cull, current_thread);
-  engine->cull_and_draw_together(_cdraw, current_thread);
-  engine->draw_bins(_draw, current_thread);
-  engine->process_events(_window, current_thread);
+  if (!_cull.empty()) {
+    engine->cull_to_bins(_cull, current_thread);
+  }
+  if (!_cdraw.empty()) {
+    engine->cull_and_draw_together(_cdraw, current_thread);
+  }
+  if (!_draw.empty()) {
+    engine->draw_bins(_draw, current_thread);
+  }
+  if (!_window.empty()) {
+    engine->process_events(_window, current_thread);
+  }
 
   // If any GSG's on the list have no more outstanding pointers, clean them
   // up.  (We are in the draw thread for all of these GSG's.)