From 86b3469fbff161a99db39131a810c06ba0ba2767 Mon Sep 17 00:00:00 2001
From: Torsten Dreyer <torsten@t3r.de>
Date: Wed, 30 Apr 2014 16:41:27 +0200
Subject: [PATCH] JSBSim: fix zero agl above scenery discontinuity

see http://osdir.com/ml/flightgear-sim/2014-04/msg00145.html
---
 src/FDM/JSBSim/JSBSim.cxx | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/FDM/JSBSim/JSBSim.cxx b/src/FDM/JSBSim/JSBSim.cxx
index 91c4dd615..c27356da2 100644
--- a/src/FDM/JSBSim/JSBSim.cxx
+++ b/src/FDM/JSBSim/JSBSim.cxx
@@ -1331,9 +1331,11 @@ FGJSBsim::get_agl_ft(double t, const double pt[3], double alt_off,
 {
   const simgear::BVHMaterial* material;
   simgear::BVHNode::Id id;
-  if (!FGInterface::get_agl_ft(t, pt, alt_off, contact, normal, vel,
-                               angularVel, material, id))
-    return false;
+
+  // don't check the return value and continue above scenery discontinuity
+  // see http://osdir.com/ml/flightgear-sim/2014-04/msg00145.html
+  FGInterface::get_agl_ft(t, pt, alt_off, contact, normal, vel,
+                               angularVel, material, id);
 
   SGGeod geodPt = SGGeod::fromCart(SG_FEET_TO_METER*SGVec3d(pt));
   SGQuatd hlToEc = SGQuatd::fromLonLat(geodPt);