Geometry3D is a Java library which provides support for vector based calculations.

Currently, it is possible to create planes as well as lines, line segments and rays. The library is able to calculate the intersection of two lines and the intersection of a line with a plane.

There are two basic types available, points and vectors. Points are defined in the class Point3D, vectors are defined in the class Vector3D. A point can be created using three dobules, one for the x-coordinate, one for the y-coordinate and one for the z-coordinate.

Point3D p = new Point3D( 2.05, 1.73, -0.26 );

A vector can be created from three doubles, two points or nothing.

Vector3D a = new Vector3D( 4.23, -5.22, -0.02 );
Vector3D b = new Vector3D( new Point3D( 2.05, 1.73, -0.26 ), new Point3D( 4.13, -2.37, -2.06 ) );
Vector3D c = new Vector3D();

The first vector a has 4.23 as x-part, -5.33 as y-part and -0.02 as z-part. The second vector b is the vector between the first point and the second point with 2.08 as x-part, -4.1 as y-part and -1.8 as z-part. The third vector is the null-vector with 0 as x-, y- and z-part.

There are a few complex types available, which are made up using the previously explained basic types.

All linear objects are represented by a subclass of AbstractLine3D. Available subclasses are Line3D, Ray3D and Line3DSegment which are the representation of a line, a ray or, respectively, a line segment.

A Line3D can be created from either two instances of Point3D or one instance of Point3D and one instance of Vector3D. The resulting Line3D contains both Point3Ds in the first case or contains the Point3D and has the Vector3D as its direction in the second case.

A Ray3D can be created from two Point3Ds. The first Point3D is used as the origin of the Ray3D, while the second Point3D is just some other point of the Ray3D.

A Line3DSegment can be created from two Point3Ds. The first Point3D is the beginning, the second Point3D is the end of the Line3DSegment.

A Plane3D is made up of three Point3Ds. Each Point3D will be part of the resulting Plane3D.

To calculate intersections between two complex types, static methods of the class Geometry3DUtils are used. The intersection of two AbstractLine3Ds is calculated by calling Geometry3DUtils.intersectionOfTwoLines( a, b ):

Point3D intersection = Geometry3DUtils.intersectionOfTwoLines( someRay, someLineSegment );

The intersection of an AbstractLine3D and a Plane3D is calculated by calling Geometry3DUtils.intersectionOfLineWithPlane( l, p ):

Point3D intersection = Geometry3DUtils.intersectionOfLineWithPlane( someLine, somePlane );

Or with a Ray3D:

Point3D intersection = Geometry3DUtils.intersectionOfLineWithPlane( someRay, somePlane );