From dca213208720b7a3d83c1130ed4f3b64bdf3bff1 Mon Sep 17 00:00:00 2001
From: ThorstenB <brehmt@gmail.com>
Date: Mon, 28 Mar 2011 00:16:27 +0200
Subject: [PATCH] New property reporting worst-case frame latency. Shows
 maximum latency of any frame within the last second.

---
 src/Time/TimeManager.cxx | 10 ++++++++--
 src/Time/TimeManager.hxx |  4 +++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/Time/TimeManager.cxx b/src/Time/TimeManager.cxx
index 2e2389695..7d4ed5607 100644
--- a/src/Time/TimeManager.cxx
+++ b/src/Time/TimeManager.cxx
@@ -88,9 +88,11 @@ void TimeManager::init()
                _warp->getIntValue());
   globals->set_time_params(_impl);
     
-// frame/update-rate counters
+  // frame-rate / worst-case delay / update-rate counters
   _frameRate = fgGetNode("/sim/frame-rate", true);
+  _frameDelayMax = fgGetNode("/sim/frame-delay-max-ms", true);
   _lastFrameTime = 0;
+  _wcFrameDelayMax = 0.0;
   _frameCount = 0;
 }
 
@@ -160,7 +162,9 @@ void TimeManager::computeTimeDeltas(double& simDt, double& realDt)
   SGTimeStamp currentStamp;
   currentStamp.stamp();
   double dt = (currentStamp - _lastStamp).toSecs();
-  
+  if (dt > _wcFrameDelayMax)
+      _wcFrameDelayMax = dt;
+
 // Limit the time we need to spend in simulation loops
 // That means, if the /sim/max-simtime-per-frame value is strictly positive
 // you can limit the maximum amount of time you will do simulations for
@@ -251,7 +255,9 @@ void TimeManager::computeFrameRate()
   // Calculate frame rate average
   if ((_impl->get_cur_time() != _lastFrameTime)) {
     _frameRate->setIntValue(_frameCount);
+    _frameDelayMax->setDoubleValue(_wcFrameDelayMax*1000);
     _frameCount = 0;
+    _wcFrameDelayMax = 0.0;
   }
   
   _lastFrameTime = _impl->get_cur_time();
diff --git a/src/Time/TimeManager.hxx b/src/Time/TimeManager.hxx
index 59aa03616..edf498013 100644
--- a/src/Time/TimeManager.hxx
+++ b/src/Time/TimeManager.hxx
@@ -78,9 +78,11 @@ private:
   SGPropertyNode_ptr _longitudeDeg;
   SGPropertyNode_ptr _latitudeDeg;
   
-// frame-rate / update-rate counters  
+  // frame-rate / worst-case delay / update-rate counters
   SGPropertyNode_ptr _frameRate;
+  SGPropertyNode_ptr _frameDelayMax;
   time_t _lastFrameTime;
+  double _wcFrameDelayMax;
   int _frameCount;
 };