IsConvex Class Reference

Inheritance diagram for IsConvex:

Collaboration diagram for IsConvex:

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

Static Public Member Functions
static boolean	isConvex (Polygon p)

Member Function Documentation

attribute()

boolean attribute

(

Geometry

geom

)

References IsConvex.isConvex().

                                                {
                if (geom instanceof LinearRing || geom instanceof Polygon) {
            boolean isConvex = isConvex((Polygon)geom);
            return isConvex;
        }
        return false;
        }

evaluate()

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

inherited

References GeometricBinaryAttributeFunction.attribute(), and LiteralRegistry.getLiteral().

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

        }

getURI()

String getURI

(

)

References POSTGIS.st_isConvex.

                               {
                return POSTGIS.st_isConvex.stringValue();
        }

isConvex()

static boolean isConvex ( Polygon  p )

static

References Coordinate.x, and Coordinate.y.

Referenced by IsConvex.attribute().

                                                  {
        LinearRing r = (LinearRing) p.getExteriorRing();
        int sign = 0;
        for(int i = 1; i < r.getNumPoints(); ++i) {
            Coordinate c0 = r.getCoordinateN(i == 0 ? r.getNumPoints() - 1 : i - 1);
            Coordinate c1 = r.getCoordinateN(i);
            Coordinate c2 = r.getCoordinateN(i == r.getNumPoints() - 1 ? 0 : i + 1);
            double dx1 = c1.x - c0.x;
            double dy1 = c1.y - c0.y;
            double dx2 = c2.x - c1.x;
            double dy2 = c2.y - c2.y;
            double z = dx1 * dy2 - dy1 * dx2;
            int s = z >= 0.0 ? 1 : -1;
            if(sign == 0) {
                sign = s; 
            } else if(sign != s) {
                return false;
            }
        }
        return true;
    }