Class CGAlgorithmsDD

Implements basic computational geometry algorithms using DD arithmetic.

Inheritance
object
CGAlgorithmsDD
Inherited Members
Namespace: NetTopologySuite.Algorithm
Assembly: NetTopologySuite.dll
Syntax
public static class CGAlgorithmsDD

Methods

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Intersection(Coordinate, Coordinate, Coordinate, Coordinate)

Computes an intersection point between two lines using DD arithmetic. If the lines are parallel (either identical or separate) a null value is returned.

Declaration
public static Coordinate Intersection(Coordinate p1, Coordinate p2, Coordinate q1, Coordinate q2)
Parameters
Type Name Description
Coordinate p1

An endpoint of line segment 1
Coordinate p2

An endpoint of line segment 1
Coordinate q1

An endpoint of line segment 2
Coordinate q2

An endpoint of line segment 2
Returns
Type Description
Coordinate

An intersection point if one exists, or null if lines are parallel.
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OrientationIndex(Coordinate, Coordinate, Coordinate)

Returns the index of the direction of the point q relative to a vector specified by p1-p2.

Declaration
public static int OrientationIndex(Coordinate p1, Coordinate p2, Coordinate q)
Parameters
Type Name Description
Coordinate p1

The origin point of the vector
Coordinate p2

The final point of the vector
Coordinate q

the point to compute the direction to
Returns
Type Description
int
  • 1 if q is counter-clockwise (left) from p1-p2
  • -1 if q is clockwise (right) from p1-p2
  • 0 if q is collinear with p1-p2
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OrientationIndex(double, double, double, double, double, double)

Returns the index of the direction of the point q relative to a vector specified by p1-p2.

Declaration
public static int OrientationIndex(double p1x, double p1y, double p2x, double p2y, double qx, double qy)
Parameters
Type Name Description
double p1x

The x-ordinate of the origin point of the vector
double p1y

The y-ordinate of the origin point of the vector
double p2x

The x-ordinate of the final point of the vector
double p2y

The y-ordinate of the final point of the vector
double qx

The x-ordinate of the point to compute the direction to
double qy

The y-ordinate of the point to compute the direction to
Returns
Type Description
int
  • 1 if q is counter-clockwise (left) from p1-p2
  • -1 if q is clockwise (right) from p1-p2
  • 0 if q is collinear with p1-p2
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SignOfDet2x2(DD, DD, DD, DD)

Computes the sign of the determinant of the 2x2 matrix with the given entries.

Declaration
public static int SignOfDet2x2(DD x1, DD y1, DD x2, DD y2)
Parameters
Type Name Description
DD x1
DD y1
DD x2
DD y2
Returns
Type Description
int
  • -1 if the determinant is negative,
  • 1 if the determinant is positive,
  • 0 if the determinant is 0.