X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=src%2FMain%2Fviewer.cxx;h=57e60f48110007c8eff18f06cd0f8fc05f2271b9;hb=38226af24ec01e8f0a20d7fd73ef838a69f6ef25;hp=ffa05fc3f3499b4160771df8af9b43eb1759ee81;hpb=11a371b31377905933b2d89f752a32d1b988e5cb;p=flightgear.git

diff --git a/src/Main/viewer.cxx b/src/Main/viewer.cxx
index ffa05fc3f..57e60f481 100644
--- a/src/Main/viewer.cxx
+++ b/src/Main/viewer.cxx
@@ -28,13 +28,13 @@
 #endif
 
 #include <simgear/compiler.h>
+#include <cassert>
 
 #include "fg_props.hxx"
 
 #include <simgear/debug/logstream.hxx>
 #include <simgear/constants.h>
 #include <simgear/scene/model/placement.hxx>
-#include <simgear/math/vector.hxx>
 
 #include <Main/globals.hxx>
 #include <Scenery/scenery.hxx>
@@ -289,7 +289,14 @@ void
 FGViewer::setHeadingOffset_deg (double heading_offset_deg)
 {
   _dirty = true;
-  _heading_offset_deg = heading_offset_deg;
+  if (_at_model && (_offset_m.x() == 0.0)&&(_offset_m.z() == 0.0))
+  {
+      /* avoid optical effects (e.g. rotating sky) when "looking at" with
+       * heading offsets x==z==0 (view heading cannot change). */
+      _heading_offset_deg = 0.0;
+  }
+  else
+      _heading_offset_deg = heading_offset_deg;
 }
 
 void
@@ -317,6 +324,14 @@ void
 FGViewer::setGoalHeadingOffset_deg (double goal_heading_offset_deg)
 {
   _dirty = true;
+  if (_at_model && (_offset_m.x() == 0.0)&&(_offset_m.z() == 0.0))
+  {
+      /* avoid optical effects (e.g. rotating sky) when "looking at" with
+       * heading offsets x==z==0 (view heading cannot change). */
+      _goal_heading_offset_deg = 0.0;
+      return;
+  }
+  
   _goal_heading_offset_deg = goal_heading_offset_deg;
   while ( _goal_heading_offset_deg < 0.0 ) {
     _goal_heading_offset_deg += 360;
@@ -651,6 +666,8 @@ FGViewer::update (double dt)
     }
   }
   recalc();
-  _cameraGroup->update(toOsg(_absolute_view_pos), toOsg(mViewOrientation));
-  _cameraGroup->setCameraParameters(get_v_fov(), get_aspect_ratio());
+  if( fgGetBool( "/sim/rendering/draw-otw", true ) ) {
+    _cameraGroup->update(toOsg(_absolute_view_pos), toOsg(mViewOrientation));
+    _cameraGroup->setCameraParameters(get_v_fov(), get_aspect_ratio());
+  }
 }