280 lines
10 KiB
C++
280 lines
10 KiB
C++
/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
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*
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* This library is open source and may be redistributed and/or modified under
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* the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
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* (at your option) any later version. The full license is in LICENSE file
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* included with this distribution, and on the openscenegraph.org website.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* OpenSceneGraph Public License for more details.
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*/
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#ifndef OSG_COORDINATESYSTEMNODE
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#define OSG_COORDINATESYSTEMNODE 1
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#include <osg/Group>
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#include <osg/Matrixd>
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namespace osg
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{
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const double WGS_84_RADIUS_EQUATOR = 6378137.0;
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const double WGS_84_RADIUS_POLAR = 6356752.3142;
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/** EllipsoidModel encapsulates the ellipsoid used to model astronomical bodies,
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* such as sun, planets, moon etc.
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* All distance quantities (i.e. heights + radius) are in meters,
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* and latitude and longitude are in radians.*/
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class EllipsoidModel : public Object
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{
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public:
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/** WGS_84 is a common representation of the earth's spheroid */
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EllipsoidModel(double radiusEquator = WGS_84_RADIUS_EQUATOR,
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double radiusPolar = WGS_84_RADIUS_POLAR):
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_radiusEquator(radiusEquator),
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_radiusPolar(radiusPolar) { computeCoefficients(); }
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EllipsoidModel(const EllipsoidModel& et,const CopyOp& copyop=CopyOp::SHALLOW_COPY):
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Object(et,copyop),
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_radiusEquator(et._radiusEquator),
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_radiusPolar(et._radiusPolar) { computeCoefficients(); }
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META_Object(osg,EllipsoidModel);
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void setRadiusEquator(double radius) { _radiusEquator = radius; computeCoefficients(); }
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double getRadiusEquator() const { return _radiusEquator; }
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void setRadiusPolar(double radius) { _radiusPolar = radius; computeCoefficients(); }
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double getRadiusPolar() const { return _radiusPolar; }
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inline void convertLatLongHeightToXYZ(double latitude, double longitude, double height,
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double& X, double& Y, double& Z) const;
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inline void convertXYZToLatLongHeight(double X, double Y, double Z,
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double& latitude, double& longitude, double& height) const;
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inline void computeLocalToWorldTransformFromLatLongHeight(double latitude, double longitude, double height, osg::Matrixd& localToWorld) const;
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inline void computeLocalToWorldTransformFromXYZ(double X, double Y, double Z, osg::Matrixd& localToWorld) const;
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inline void computeCoordinateFrame(double latitude, double longitude, osg::Matrixd& localToWorld) const;
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inline osg::Vec3d computeLocalUpVector(double X, double Y, double Z) const;
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// Convenience method for determining if EllipsoidModel is a stock WGS84 ellipsoid
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inline bool isWGS84() const {return(_radiusEquator == WGS_84_RADIUS_EQUATOR && _radiusPolar == WGS_84_RADIUS_POLAR);}
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// Compares two EllipsoidModel by comparing critical internal values.
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// Ignores _eccentricitySquared since it's just a cached value derived from
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// the _radiusEquator and _radiusPolar members.
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friend bool operator == ( const EllipsoidModel & e1, const EllipsoidModel& e2) {return(e1._radiusEquator == e2._radiusEquator && e1._radiusPolar == e2._radiusPolar);}
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protected:
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void computeCoefficients()
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{
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double flattening = (_radiusEquator-_radiusPolar)/_radiusEquator;
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_eccentricitySquared = 2*flattening - flattening*flattening;
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}
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double _radiusEquator;
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double _radiusPolar;
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double _eccentricitySquared;
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};
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/** CoordinateFrame encapsulates the orientation of east, north and up.*/
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typedef Matrixd CoordinateFrame;
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/** CoordinateSystem encapsulate the coordinate system that is associated with objects in a scene.
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For an overview of common earth bases coordinate systems see http://www.colorado.edu/geography/gcraft/notes/coordsys/coordsys_f.html */
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class OSG_EXPORT CoordinateSystemNode : public Group
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{
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public:
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CoordinateSystemNode();
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CoordinateSystemNode(const std::string& format, const std::string& cs);
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/** Copy constructor using CopyOp to manage deep vs shallow copy.*/
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CoordinateSystemNode(const CoordinateSystemNode&,const osg::CopyOp& copyop=osg::CopyOp::SHALLOW_COPY);
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META_Node(osg,CoordinateSystemNode);
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/** Set the coordinate system node up by copying the format, coordinate system string, and ellipsoid model of another coordinate system node.*/
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void set(const CoordinateSystemNode& csn);
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/** Set the coordinate system format string. Typical values would be WKT, PROJ4, USGS etc.*/
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void setFormat(const std::string& format) { _format = format; }
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/** Get the coordinate system format string.*/
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const std::string& getFormat() const { return _format; }
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/** Set the CoordinateSystem reference string, should be stored in a form consistent with the Format.*/
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void setCoordinateSystem(const std::string& cs) { _cs = cs; }
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/** Get the CoordinateSystem reference string.*/
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const std::string& getCoordinateSystem() const { return _cs; }
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/** Set EllipsoidModel to describe the model used to map lat, long and height into geocentric XYZ and back. */
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void setEllipsoidModel(EllipsoidModel* ellipsode) { _ellipsoidModel = ellipsode; }
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/** Get the EllipsoidModel.*/
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EllipsoidModel* getEllipsoidModel() { return _ellipsoidModel.get(); }
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/** Get the const EllipsoidModel.*/
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const EllipsoidModel* getEllipsoidModel() const { return _ellipsoidModel.get(); }
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/** Compute the local coordinate frame for specified point.*/
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CoordinateFrame computeLocalCoordinateFrame(const Vec3d& position) const;
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/** Compute the local up-vector for specified point.*/
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osg::Vec3d computeLocalUpVector(const Vec3d& position) const;
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protected:
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virtual ~CoordinateSystemNode() {}
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std::string _format;
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std::string _cs;
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ref_ptr<EllipsoidModel> _ellipsoidModel;
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};
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////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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// implement inline methods.
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//
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inline void EllipsoidModel::convertLatLongHeightToXYZ(double latitude, double longitude, double height,
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double& X, double& Y, double& Z) const
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{
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// for details on maths see http://www.colorado.edu/geography/gcraft/notes/datum/gif/llhxyz.gif
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double sin_latitude = sin(latitude);
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double cos_latitude = cos(latitude);
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double N = _radiusEquator / sqrt( 1.0 - _eccentricitySquared*sin_latitude*sin_latitude);
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X = (N+height)*cos_latitude*cos(longitude);
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Y = (N+height)*cos_latitude*sin(longitude);
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Z = (N*(1-_eccentricitySquared)+height)*sin_latitude;
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}
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inline void EllipsoidModel::convertXYZToLatLongHeight(double X, double Y, double Z,
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double& latitude, double& longitude, double& height) const
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{
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// handle polar and center-of-earth cases directly.
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if (X != 0.0)
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longitude = atan2(Y,X);
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else
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{
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if (Y > 0.0)
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longitude = PI_2;
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else if (Y < 0.0)
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longitude = -PI_2;
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else
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{
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// at pole or at center of the earth
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longitude = 0.0;
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if (Z > 0.0)
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{ // north pole.
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latitude = PI_2;
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height = Z - _radiusPolar;
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}
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else if (Z < 0.0)
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{ // south pole.
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latitude = -PI_2;
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height = -Z - _radiusPolar;
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}
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else
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{ // center of earth.
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latitude = PI_2;
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height = -_radiusPolar;
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}
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return;
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}
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}
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// http://www.colorado.edu/geography/gcraft/notes/datum/gif/xyzllh.gif
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double p = sqrt(X*X + Y*Y);
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double theta = atan2(Z*_radiusEquator , (p*_radiusPolar));
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double eDashSquared = (_radiusEquator*_radiusEquator - _radiusPolar*_radiusPolar)/
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(_radiusPolar*_radiusPolar);
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double sin_theta = sin(theta);
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double cos_theta = cos(theta);
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latitude = atan( (Z + eDashSquared*_radiusPolar*sin_theta*sin_theta*sin_theta) /
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(p - _eccentricitySquared*_radiusEquator*cos_theta*cos_theta*cos_theta) );
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double sin_latitude = sin(latitude);
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double N = _radiusEquator / sqrt( 1.0 - _eccentricitySquared*sin_latitude*sin_latitude);
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height = p/cos(latitude) - N;
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}
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inline void EllipsoidModel::computeLocalToWorldTransformFromLatLongHeight(double latitude, double longitude, double height, osg::Matrixd& localToWorld) const
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{
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double X, Y, Z;
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convertLatLongHeightToXYZ(latitude,longitude,height,X,Y,Z);
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localToWorld.makeTranslate(X,Y,Z);
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computeCoordinateFrame(latitude, longitude, localToWorld);
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}
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inline void EllipsoidModel::computeLocalToWorldTransformFromXYZ(double X, double Y, double Z, osg::Matrixd& localToWorld) const
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{
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double latitude, longitude, height;
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convertXYZToLatLongHeight(X,Y,Z,latitude,longitude,height);
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localToWorld.makeTranslate(X,Y,Z);
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computeCoordinateFrame(latitude, longitude, localToWorld);
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}
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inline void EllipsoidModel::computeCoordinateFrame(double latitude, double longitude, osg::Matrixd& localToWorld) const
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{
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// Compute up vector
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osg::Vec3d up ( cos(longitude)*cos(latitude), sin(longitude)*cos(latitude), sin(latitude));
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// Compute east vector
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osg::Vec3d east (-sin(longitude), cos(longitude), 0);
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// Compute north vector = outer product up x east
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osg::Vec3d north = up ^ east;
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// set matrix
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localToWorld(0,0) = east[0];
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localToWorld(0,1) = east[1];
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localToWorld(0,2) = east[2];
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localToWorld(1,0) = north[0];
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localToWorld(1,1) = north[1];
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localToWorld(1,2) = north[2];
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localToWorld(2,0) = up[0];
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localToWorld(2,1) = up[1];
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localToWorld(2,2) = up[2];
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}
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inline osg::Vec3d EllipsoidModel::computeLocalUpVector(double X, double Y, double Z) const
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{
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// Note latitude is angle between normal to ellipsoid surface and XY-plane
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double latitude;
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double longitude;
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double altitude;
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convertXYZToLatLongHeight(X,Y,Z,latitude,longitude,altitude);
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// Compute up vector
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return osg::Vec3d( cos(longitude) * cos(latitude),
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sin(longitude) * cos(latitude),
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sin(latitude));
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}
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}
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#endif
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