Angle Class Reference

Calculates an angle between three given points. More...

Inheritance diagram for Angle:

Collaboration diagram for Angle:

Public Member Functions
String	getURI ()
Value	evaluate (ValueFactory valueFactory, Value... args) throws ValueExprEvaluationException

Static Public Member Functions
static double	findAngle (Coordinate a, Coordinate b, Coordinate c)
	Calculates an angle between three different coordinates. More...

Protected Member Functions
Double	relation (Geometry geom, Geometry geom2, Geometry geom3)

Detailed Description

Calculates an angle between three given points.

Member Function Documentation

evaluate()

Value evaluate ( ValueFactory  valueFactory, Value...  args  ) throws ValueExprEvaluationException

inherited

                                                                                                            {
                if (args.length != 3) {
                        throw new ValueExprEvaluationException(getURI() + " requires exactly 3 arguments, got " + args.length);
                }               
                
                LiteralType l=LiteralRegistry.getLiteral(((Literal)args[0]).getDatatype().toString());
                LiteralType l2=LiteralRegistry.getLiteral(((Literal)args[1]).getDatatype().toString());
                LiteralType l3=LiteralRegistry.getLiteral(((Literal)args[2]).getDatatype().toString());
                if(l instanceof VectorLiteral && l2 instanceof VectorLiteral) {
                        Geometry geom=((VectorLiteral)l).read(args[0].stringValue());
                        Geometry geom2=((VectorLiteral)l2).read(args[1].stringValue());
                        Geometry geom3=((VectorLiteral)l3).read(args[2].stringValue());
                        Double result = relation(geom,geom2,geom3);
                        return valueFactory.createLiteral(result);
                }
                throw new ValueExprEvaluationException("Argument given is not a geometry literal");
        }

References LiteralRegistry.getLiteral(), and GeometricDoubleThreeGeometryFunction.relation().

Referenced by AngleTest.testAngle().

findAngle()

static double findAngle ( Coordinate  a, Coordinate  b, Coordinate  c  )

static

Calculates an angle between three different coordinates.

Parameters

a	the first coordinate
b	the second coordinate
c	the third coordinate

Returns

the calculated angle

                                                                                {
            double AB = Math.sqrt(Math.pow(b.x-a.x,2)+ Math.pow(b.y-a.y,2));    
            double BC = Math.sqrt(Math.pow(b.x-c.x,2)+ Math.pow(b.y-c.y,2)); 
            double AC = Math.sqrt(Math.pow(c.x-a.x,2)+ Math.pow(c.y-a.y,2));
            return Math.acos((BC*BC+AB*AB-AC*AC)/(2*BC*AB));
        }

Referenced by Angle.relation().

getURI()

String getURI

(

)

                               {
                return POSTGIS.st_angle.stringValue();
        }

References POSTGIS.st_angle.

relation()

Double relation ( Geometry  geom, Geometry  geom2, Geometry  geom3  )

protected

Reimplemented from GeometricDoubleThreeGeometryFunction.

                                                                                 {
                Coordinate coord1,coord2,coord3;
                if("Point".equals(geom.getGeometryType())) {
                        coord1=geom.getCoordinate();
                }else {
                        coord1=geom.getCentroid().getCoordinate();
                }
                if("Point".equals(geom2.getGeometryType())) {
                        coord2=geom2.getCoordinate();
                }else {
                        coord2=geom2.getCentroid().getCoordinate();
                }
                if("Point".equals(geom3.getGeometryType())) {
                        coord3=geom3.getCoordinate();
                }else {
                        coord3=geom3.getCentroid().getCoordinate();
                }
                return findAngle(coord1,coord2,coord3);
        }

References Angle.findAngle().