osgEarth::Symbology::GeometryFactory Class Reference

List of all members.

Public Member Functions
	GeometryFactory (const SpatialReference *srs=0L)
Geometry *	createCircle (const osg::Vec3d &center, const Linear &radius, unsigned numSegments=0)
Geometry *	createArc (const osg::Vec3d &center, const Linear &radius, const Angular &startAngle, const Angular &endAngle, unsigned numSegments=0)
Geometry *	createEllipse (const osg::Vec3d &center, const Linear &radiusMajor, const Linear &radiusMinor, const Angular &rotationAngle, unsigned numSegments=0)
Protected Attributes
osg::ref_ptr< const SpatialReference >	_srs

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Detailed Description

Convenience class for building simple tessellated Geometry shapes.

Definition at line 36 of file GeometryFactory.

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Constructor & Destructor Documentation

GeometryFactory::GeometryFactory

(

const SpatialReference *

srs = 0L

)

Constructs the factory.

Parameters:

srs	The spatial reference in which to create the geometry, or NULL to create simple localized geometry.

Definition at line 27 of file GeometryFactory.cpp.

                                                              :
_srs( srs )
{
    //nop
}

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Member Function Documentation

Geometry * GeometryFactory::createArc	(	const osg::Vec3d &	center,
		const Linear &	radius,
		const Angular &	startAngle,
		const Angular &	endAngle,
		unsigned	numSegments = 0
	)

Creates an arc geometry.

Parameters:

center	Center point (must be in map SRS if a map was provided in ctor)
radius	Arc radius
start	Starting angle of the arc
end	Ending angle of the arc
numSegments	Number of circumference segments, or zero to automatically calculate it

Definition at line 84 of file GeometryFactory.cpp.

{
    Geometry* geom = new LineString();

    if ( numSegments == 0 )
    {
        // automatically calculate
        double segLen = radius.as(Units::METERS) / 8.0;
        double circumference = 2*osg::PI*radius.as(Units::METERS);
        numSegments = (unsigned)::ceil(circumference / segLen);
    }

    double startRad = std::min( start.as(Units::RADIANS), end.as(Units::RADIANS) );
    double endRad   = std::max( start.as(Units::RADIANS), end.as(Units::RADIANS) );
    double span     = endRad - startRad;    
    double step     = span/(double)numSegments;

    if ( _srs.valid() && _srs->isGeographic() )
    {
        double earthRadius = _srs->getEllipsoid()->getRadiusEquator();
        double lat = osg::DegreesToRadians(center.y());
        double lon = osg::DegreesToRadians(center.x());
        double rM  = radius.as(Units::METERS);

        for( unsigned i=0; i<=numSegments; ++i )
        {
            double angle = startRad + step*(double)i;
            double clat, clon;
            GeoMath::destination( lat, lon, angle, rM, clat, clon, earthRadius );
            geom->push_back( osg::Vec3d(osg::RadiansToDegrees(clon), osg::RadiansToDegrees(clat), center.z()) );
        }
    }

    else
    {
        double rM = radius.as(Units::METERS);

        for( unsigned i=0; i<=numSegments; ++i )
        {
            double angle = startRad + step*(double)i;
            double x, y;
            x = center.x() + sin(angle)*rM;
            y = center.y() + cos(angle)*rM;
            geom->push_back( osg::Vec3d(x, y, center.z()) );
        }
    }

    return geom;
}

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Geometry * GeometryFactory::createCircle	(	const osg::Vec3d &	center,
		const Linear &	radius,
		unsigned	numSegments = 0
	)

Creates a circle geometry.

Parameters:

center	Center point (must be in map SRS if a map was provided in ctor)
radius	Circle radius
numSegments	Number of circumference segments, or zero to automatically calculate it

Definition at line 34 of file GeometryFactory.cpp.

{
    Polygon* geom = new Polygon();

    if ( numSegments == 0 )
    {
        // automatically calculate
        double segLen = radius.as(Units::METERS) / 8.0;
        double circumference = 2*osg::PI*radius.as(Units::METERS);
        numSegments = (unsigned)::ceil(circumference / segLen);
    }
    
    double segAngle = (2.0*osg::PI)/(double)numSegments;

    if ( _srs.valid() && _srs->isGeographic() )
    {
        double earthRadius = _srs->getEllipsoid()->getRadiusEquator();
        double lat = osg::DegreesToRadians(center.y());
        double lon = osg::DegreesToRadians(center.x());
        double rM  = radius.as(Units::METERS);

        for( unsigned i=0; i<numSegments; ++i )
        {
            double angle = segAngle * (double)i;
            double clat, clon;
            GeoMath::destination( lat, lon, angle, rM, clat, clon, earthRadius );
            geom->push_back( osg::Vec3d(osg::RadiansToDegrees(clon), osg::RadiansToDegrees(clat), center.z()) );
        }
    }

    else
    {
        double rM = radius.as(Units::METERS);

        for( unsigned i=0; i<numSegments; ++i )
        {
            double angle = segAngle * (double)i;
            double x, y;
            x = center.x() + sin(angle)*rM;
            y = center.y() + cos(angle)*rM;
            geom->push_back( osg::Vec3d(x, y, center.z()) );
        }
    }

    return geom;
}

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Geometry * GeometryFactory::createEllipse	(	const osg::Vec3d &	center,
		const Linear &	radiusMajor,
		const Linear &	radiusMinor,
		const Angular &	rotationAngle,
		unsigned	numSegments = 0
	)

Creates a ellipse geometry.

Parameters:

center	Center point (must be in map SRS if a map was provided in ctor)
radiusMajor	Major radius (X-axis) length
radiusMinor	Minor radius (Y-axis) length
rotationAngle	with respect to the X-axis
numSegments	Number of circumference segments, or zero to automatically calculate it

Definition at line 139 of file GeometryFactory.cpp.

{
    Polygon* geom = new Polygon();

    if ( numSegments == 0 )
    {
        // automatically calculate
        double ravgM = 0.5*(radiusMajor.as(Units::METERS) + radiusMinor.as(Units::METERS));
        double segLen = ravgM / 8.0;
        double circumference = 2*osg::PI*ravgM;
        numSegments = (unsigned)::ceil(circumference / segLen);
    }
    
    double segAngle = 2.0*osg::PI/(double)numSegments;

    if ( _srs.valid() && _srs->isGeographic() )
    {
        double earthRadius = _srs->getEllipsoid()->getRadiusEquator();
        double lat = osg::DegreesToRadians(center.y());
        double lon = osg::DegreesToRadians(center.x());
        double a = radiusMajor.as(Units::METERS);
        double b = radiusMinor.as(Units::METERS);
        double g = rotationAngle.as(Units::RADIANS) - osg::PI_2;

        for( unsigned i=0; i<numSegments; ++i )
        {
            double angle = segAngle * (double)i;
            double t = angle - osg::PI_2;
            double clat, clon;

            double rA = (b*b-a*a)*cos(2*t - 2*g) + a*a + b*b;
            double q = sqrt(2.0)*a*b*sqrt(rA);
            double r = q/rA;

            GeoMath::destination( lat, lon, angle, r, clat, clon, earthRadius );
            geom->push_back( osg::Vec3d(osg::RadiansToDegrees(clon), osg::RadiansToDegrees(clat), center.z()) );
        }
    }
    else
    {
        double a = radiusMajor.as(Units::METERS);
        double b = radiusMinor.as(Units::METERS);
        double g = rotationAngle.as(Units::RADIANS) - osg::PI_2;
        double sing = sin(g), cosg = cos(g);

        for( unsigned i=0; i<numSegments; ++i )
        {
            double angle = segAngle * (double)i;
            double t = angle - osg::PI_2;
            double cost = cos(t), sint = sin(t);
            double x = center.x() + a*cost*cosg - b*sint*sing;
            double y = center.y() + a*cost*sing + b*sint*cosg;

            geom->push_back( osg::Vec3d(x, y, center.z()) );
        }
    }

    return geom;
}

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Member Data Documentation

osg::ref_ptr<const SpatialReference> osgEarth::Symbology::GeometryFactory::_srs [protected]

Definition at line 89 of file GeometryFactory.

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The documentation for this class was generated from the following files:

• /home/cube/sources/osgearth/src/osgEarthSymbology/GeometryFactory
• /home/cube/sources/osgearth/src/osgEarthSymbology/GeometryFactory.cpp