From 600726976c2513cac582538bf4cb8e4a569e4010 Mon Sep 17 00:00:00 2001
From: timoore <timoore>
Date: Tue, 4 Mar 2008 08:53:27 +0000
Subject: [PATCH] Add methods to SGGeod to return OSG Matrix objects for local
 frames.

Methods have been added for Z down (simulation) and Z up frames.
---
 simgear/math/Makefile.am |  1 +
 simgear/math/SGGeod.cxx  | 51 ++++++++++++++++++++++++++++++++++++++++
 simgear/math/SGGeod.hxx  | 14 +++++++++++
 3 files changed, 66 insertions(+)
 create mode 100644 simgear/math/SGGeod.cxx

diff --git a/simgear/math/Makefile.am b/simgear/math/Makefile.am
index d9124926..75bec30e 100644
--- a/simgear/math/Makefile.am
+++ b/simgear/math/Makefile.am
@@ -48,6 +48,7 @@ libsgmath_a_SOURCES = \
 	leastsqs.cxx \
 	sg_random.c \
 	vector.cxx \
+	SGGeod.cxx \
 	SGGeodesy.cxx
 
 INCLUDES = -I$(top_srcdir)
diff --git a/simgear/math/SGGeod.cxx b/simgear/math/SGGeod.cxx
new file mode 100644
index 00000000..01e857a2
--- /dev/null
+++ b/simgear/math/SGGeod.cxx
@@ -0,0 +1,51 @@
+// Copyright (C) 2008  Tim Moore timoore@redhat.com
+//
+// This library is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Library General Public
+// License as published by the Free Software Foundation; either
+// version 2 of the License, or (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Library General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+//
+
+#include "SGMath.hxx"
+
+osg::Matrix SGGeod::makeSimulationFrameRelative()
+{
+    SGQuatd hlOr = SGQuatd::fromLonLat(*this);
+    return osg::Matrix(hlOr.osg());
+}
+
+osg::Matrix SGGeod::makeSimulationFrame()
+{
+    osg::Matrix result(makeSimulationFrameRelative());
+    SGVec3d coord;
+    SGGeodesy::SGGeodToCart(*this, coord);
+    result.setTrans(coord.osg());
+    return result;
+}
+
+osg::Matrix SGGeod::makeZUpFrameRelative()
+{
+    osg::Matrix result(makeSimulationFrameRelative());
+    // 180 degree rotation around Y axis
+    osg::Quat flip(0.0, 1.0, 0.0, 0.0);
+    result.preMult(osg::Matrix(flip));
+    return result;
+}
+
+osg::Matrix SGGeod::makeZUpFrame()
+{
+    osg::Matrix result(makeZUpFrameRelative());
+    SGVec3d coord;
+    SGGeodesy::SGGeodToCart(*this, coord);
+    result.setTrans(coord.osg());
+    return result;
+}
diff --git a/simgear/math/SGGeod.hxx b/simgear/math/SGGeod.hxx
index 50c6b97d..4fea57ac 100644
--- a/simgear/math/SGGeod.hxx
+++ b/simgear/math/SGGeod.hxx
@@ -20,6 +20,8 @@
 
 #include <simgear/constants.h>
 
+#include <osg/Matrix>
+
 // #define SG_GEOD_NATIVE_DEGREE
 
 /// Class representing a geodetic location
@@ -78,6 +80,18 @@ public:
   /// Set the geodetic elevation from the argument given in feet
   void setElevationFt(double elevation);
 
+  // Create a local coordinate frame in the earth-centered frame of
+  // reference. X points north, Z points down.
+  // makeSimulationFrameRelative() only includes rotation.
+    
+  osg::Matrix makeSimulationFrameRelative();
+  osg::Matrix makeSimulationFrame();    
+
+  // Create a Z-up local coordinate frame in the earth-centered frame
+  // of reference. This is what scenery models, etc. expect.
+  // makeZUpFrameRelative() only includes rotation.
+  osg::Matrix makeZUpFrameRelative();
+  osg::Matrix makeZUpFrame();    
 private:
   /// This one is private since construction is not unique if you do
   /// not know the units of the arguments. Use the factory methods for
-- 
2.39.5