From 104dc1170bd6de4208e34aafaf31922b5f5f01ef Mon Sep 17 00:00:00 2001
From: Thomas Geymayer <tomgey@gmail.com>
Date: Thu, 18 Sep 2014 00:16:09 +0200
Subject: [PATCH] Use black clear color only at high altitudes.

Black clear color can cause visual glitches on low
altitudes, but a black space is much nicer, so just
switch at 300.000 ft.
---
 src/Viewer/renderer.cxx | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/Viewer/renderer.cxx b/src/Viewer/renderer.cxx
index 811b0225a..15de4785b 100644
--- a/src/Viewer/renderer.cxx
+++ b/src/Viewer/renderer.cxx
@@ -1615,7 +1615,14 @@ FGRenderer::update( ) {
     current__view->set_dirty();
   
     osg::Camera *camera = viewer->getCamera();
-    camera->setClearColor(osg::Vec4(0, 0, 0, 0));
+
+    osg::Vec4 clear_color = _altitude_ft->getDoubleValue() < 300000
+                          ? toOsg(l->adj_fog_color())
+                          // skydome ends at ~328000 ft and would produce a
+                          // strange looking grey space -> black looks much
+                          // better :-)
+                          : osg::Vec4(0, 0, 0, 1);
+    camera->setClearColor(clear_color);
 
     updateSky();