org.tinfour.common

Class SimpleTriangle

java.lang.Object

org.tinfour.common.SimpleTriangle

public class SimpleTriangle
extends Object

Provides methods and elements for a simple representation of a triangle based on IQuadEdge edges.

Constructor Summary

Constructors

Constructor and Description
SimpleTriangle(IIncrementalTin tin, IQuadEdge a) Construct a simple triangle from the specified edges.
SimpleTriangle(IIncrementalTin tin, IQuadEdge a, IQuadEdge b, IQuadEdge c) Construct a simple triangle from the specified edges.

Method Summary

Modifier and Type	Method and Description
double	getArea() Gets the area of the triangle.
Circumcircle	getCircumcircle() Obtains the circumcircle for a simple triangle.
IConstraint	getContainingRegion() Gets the polygon-based constraint that contains this triangle, if any.
IQuadEdge	getEdgeA() Get edge a from the triangle
IQuadEdge	getEdgeB() Get edge b from the triangle
IQuadEdge	getEdgeC() Get edge c from the triangle
Path2D	getPath2D(AffineTransform transform) Gets a Java Path2D based on the geometry of the triangle mapped through an optional affine transform.
Vertex	getVertexA() Gets vertex A of the triangle.
Vertex	getVertexB() Gets vertex B of the triangle.
Vertex	getVertexC() Gets vertex A of the triangle.
boolean	isGhost() Indicates whether the triangle is a ghost triangle.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SimpleTriangle

public SimpleTriangle(IIncrementalTin tin,
                      IQuadEdge a,
                      IQuadEdge b,
                      IQuadEdge c)

Construct a simple triangle from the specified edges. For efficiency purposes, this constructor is very lean and does not perform sanity checking on the inputs. In particular, it is essential that the specified edge be a member of the specified TIN and that the TIN must not be modified while the SimpleTriangle instance is in use.

Parameters:

tin - a reference to the TIN that was used to create this triangle.

a - a valid edge

b - a valid edge

c - a valid edge

SimpleTriangle

public SimpleTriangle(IIncrementalTin tin,
                      IQuadEdge a)

Construct a simple triangle from the specified edges. For efficiency purposes, this constructor is very lean and does not perform sanity checking on the inputs. In particular, it is essential that the specified edge be a member of the specified TIN and that the TIN must not be modified while the SimpleTriangle instance is in use.

Parameters:

tin - a reference to the TIN that was used to create this triangle.

a - a valid edge which must be a member of the specified TIN.

Method Detail

getEdgeA

public IQuadEdge getEdgeA()

Get edge a from the triangle

Returns:

a valid edge

getEdgeB

public IQuadEdge getEdgeB()

Get edge b from the triangle

Returns:

a valid edge

getEdgeC

public IQuadEdge getEdgeC()

Get edge c from the triangle

Returns:

a valid edge

getVertexA

public Vertex getVertexA()

Gets vertex A of the triangle. The method names used in this class follow the conventions of trigonometry. Vertices are labeled so that vertex A is opposite edge a, vertex B is opposite edge b, etc. This approach is slightly different than that used in other parts of the Tinfour API.

Returns:

a valid vertex

getVertexB

public Vertex getVertexB()

Gets vertex B of the triangle. The method names used in this class follow the conventions of trigonometry. Vertices are labeled so that vertex A is opposite edge a, vertex B is opposite edge b, etc. This approach is slightly different than that used in other parts of the Tinfour API.

Returns:

a valid vertex

getVertexC

public Vertex getVertexC()

Gets vertex A of the triangle. The method names used in this class follow the conventions of trigonometry. Vertices are labeled so that vertex A is opposite edge a, vertex B is opposite edge b, etc. This approach is slightly different than that used in other parts of the Tinfour API.

Returns:

a valid vertex

getArea

public double getArea()

Gets the area of the triangle. This value is positive if the triangle is given in counterclockwise order and negative if it is given in clockwise order. A value of zero indicates a degenerate triangle.

Returns:

a valid floating point number.

getContainingRegion

public IConstraint getContainingRegion()

Gets the polygon-based constraint that contains this triangle, if any.

Under ConstructionThis method is not yet complete. Because the Tinfour implementation does not yet record which side of an edge an region-based constraint lies on, there are cases involving constraint borders that will not be accurately detected. It can only reliably report membership when a triangle has at least one edge that is entirely inside a constraint area

Returns:

if the triangle is enclosed by a constraint, a valid instance; otherwise, a null.

getPath2D

public Path2D getPath2D(AffineTransform transform)

Gets a Java Path2D based on the geometry of the triangle mapped through an optional affine transform.

Parameters:

transform - a valid transform, or the null to use the identity transform.

Returns:

a valid instance of a Java Path2D

getCircumcircle

public Circumcircle getCircumcircle()

Obtains the circumcircle for a simple triangle.

This method uses an ordinary-precision computation for circumcircles that yields acceptable accuracy for well-formed triangles. Applications that need more accuracy or may need to deal with nearly degenerate triangles (nearly flat triangles) may prefer to use Tinfour's GeometricOperations class for that purpose.

Returns:

a valid instance

isGhost

public boolean isGhost()

Indicates whether the triangle is a ghost triangle. A ghost triangle is one that lies outside the bounds of a Delaunay triangulation and contains an undefined vertex.

The TriangleCollector class does not produce ghost triangles, but those created from perimeter edges may be ghosts.

Returns:

true if the triangle is a ghost triangle; otherwise, false.