geos::triangulate::quadedge::QuadEdgeSubdivision Class Reference
#include <QuadEdgeSubdivision.h>
List of all members.
Public Types |
typedef std::vector< QuadEdge * > | QuadEdgeList |
Public Member Functions |
| QuadEdgeSubdivision (const geom::Envelope &env, double tolerance) |
double | getTolerance () const |
const geom::Envelope & | getEnvelope () const |
const QuadEdgeList & | getEdges () const |
void | setLocator (std::auto_ptr< QuadEdgeLocator > locator) |
virtual QuadEdge & | makeEdge (const Vertex &o, const Vertex &d) |
virtual QuadEdge & | connect (QuadEdge &a, QuadEdge &b) |
void | remove (QuadEdge &e) |
QuadEdge * | locateFromEdge (const Vertex &v, const QuadEdge &startEdge) const |
QuadEdge * | locate (const Vertex &v) const |
QuadEdge * | locate (const geom::Coordinate &p) |
QuadEdge * | locate (const geom::Coordinate &p0, const geom::Coordinate &p1) |
QuadEdge & | insertSite (const Vertex &v) |
bool | isFrameEdge (const QuadEdge &e) const |
bool | isFrameBorderEdge (const QuadEdge &e) const |
bool | isFrameVertex (const Vertex &v) const |
bool | isOnEdge (const QuadEdge &e, const geom::Coordinate &p) const |
bool | isVertexOfEdge (const QuadEdge &e, const Vertex &v) const |
std::auto_ptr< QuadEdgeList > | getPrimaryEdges (bool includeFrame) |
void | visitTriangles (TriangleVisitor *triVisitor, bool includeFrame) |
std::auto_ptr
< geom::MultiLineString > | getEdges (const geom::GeometryFactory &geomFact) |
std::auto_ptr
< geom::GeometryCollection > | getTriangles (const geom::GeometryFactory &geomFact) |
std::auto_ptr
< geom::GeometryCollection > | getVoronoiDiagram (const geom::GeometryFactory &geomFact) |
std::auto_ptr
< geom::MultiLineString > | getVoronoiDiagramEdges (const geom::GeometryFactory &geomFact) |
std::auto_ptr< std::vector
< geom::Geometry * > > | getVoronoiCellPolygons (const geom::GeometryFactory &geomFact) |
std::auto_ptr< std::vector
< geom::Geometry * > > | getVoronoiCellEdges (const geom::GeometryFactory &geomFact) |
std::auto_ptr
< QuadEdgeSubdivision::QuadEdgeList > | getVertexUniqueEdges (bool includeFrame) |
std::auto_ptr< geom::Geometry > | getVoronoiCellPolygon (QuadEdge *qe, const geom::GeometryFactory &geomFact) |
std::auto_ptr< geom::Geometry > | getVoronoiCellEdge (QuadEdge *qe, const geom::GeometryFactory &geomFact) |
Static Public Member Functions |
static void | getTriangleEdges (const QuadEdge &startQE, const QuadEdge *triEdge[3]) |
Detailed Description
A class that contains the QuadEdges representing a planar subdivision that models a triangulation. The subdivision is constructed using the quadedge algebra defined in the classs QuadEdge. All metric calculations are done in the Vertex class. In addition to a triangulation, subdivisions support extraction of Voronoi diagrams. This is easily accomplished, since the Voronoi diagram is the dual of the Delaunay triangulation.
Subdivisions can be provided with a tolerance value. Inserted vertices which are closer than this value to vertices already in the subdivision will be ignored. Using a suitable tolerance value can prevent robustness failures from happening during Delaunay triangulation.
Subdivisions maintain a frame triangle around the client-created edges. The frame is used to provide a bounded "container" for all edges within a TIN. Normally the frame edges, frame connecting edges, and frame triangles are not included in client processing.
- Author:
- JTS: David Skea
-
JTS: Martin Davis
-
Benjamin Campbell
Constructor & Destructor Documentation
geos::triangulate::quadedge::QuadEdgeSubdivision::QuadEdgeSubdivision |
( |
const geom::Envelope & |
env, |
|
|
double |
tolerance | |
|
) |
| | |
Creates a new instance of a quad-edge subdivision based on a frame triangle that encloses a supplied bounding box. A new super-bounding box that contains the triangle is computed and stored.
- Parameters:
-
| env | the bouding box to surround |
| tolerance | the tolerance value for determining if two sites are equal |
Member Function Documentation
Creates a new QuadEdge connecting the destination of a to the origin of b, in such a way that all three have the same left face after the connection is complete. The quadedge is recorded in the edges list.
- Parameters:
-
- Returns:
Gets the geometry for the edges in the subdivision as a MultiLineString containing 2-point lines.
- Parameters:
-
| geomFact | the GeometryFactory to use |
- Returns:
- a MultiLineString. The caller takes ownership of the returned object.
const QuadEdgeList& geos::triangulate::quadedge::QuadEdgeSubdivision::getEdges |
( |
|
) |
const [inline] |
Gets the collection of base QuadEdges (one for every pair of vertices which is connected).
- Returns:
- a QuadEdgeList
const geom::Envelope& geos::triangulate::quadedge::QuadEdgeSubdivision::getEnvelope |
( |
|
) |
const [inline] |
Gets the envelope of the Subdivision (including the frame).
- Returns:
- the envelope
std::auto_ptr<QuadEdgeList> geos::triangulate::quadedge::QuadEdgeSubdivision::getPrimaryEdges |
( |
bool |
includeFrame |
) |
|
Gets all primary quadedges in the subdivision. A primary edge is a QuadEdge which occupies the 0'th position in its array of associated quadedges. These provide the unique geometric edges of the triangulation.
- Parameters:
-
| includeFrame | true if the frame edges are to be included |
- Returns:
- a List of QuadEdges. The caller takes ownership of the returned QuadEdgeList but not the items it contains.
double geos::triangulate::quadedge::QuadEdgeSubdivision::getTolerance |
( |
|
) |
const [inline] |
Gets the vertex-equality tolerance value used in this subdivision
- Returns:
- the tolerance value
static void geos::triangulate::quadedge::QuadEdgeSubdivision::getTriangleEdges |
( |
const QuadEdge & |
startQE, |
|
|
const QuadEdge * |
triEdge[3] | |
|
) |
| | [static] |
Gets the edges for the triangle to the left of the given QuadEdge.
- Parameters:
-
- Exceptions:
-
| IllegalArgumentException | if the edges do not form a triangle |
Gets the geometry for the triangles in a triangulated subdivision as a GeometryCollection of triangular Polygons.
- Parameters:
-
| geomFact | the GeometryFactory to use |
- Returns:
- a GeometryCollection of triangular Polygons. The caller takes ownership of the returned object.
std::auto_ptr<QuadEdgeSubdivision::QuadEdgeList> geos::triangulate::quadedge::QuadEdgeSubdivision::getVertexUniqueEdges |
( |
bool |
includeFrame |
) |
|
Gets a collection of QuadEdges whose origin vertices are a unique set which includes all vertices in the subdivision. The frame vertices can be included if required. This is useful for algorithms which require traversing the subdivision starting at all vertices. Returning a quadedge for each vertex is more efficient than the alternative of finding the actual vertices using getVertices and then locating quadedges attached to them.
- Parameters:
-
| includeFrame | true if the frame vertices should be included |
- Returns:
- a collection of QuadEdge with the vertices of the subdivision as their origins
Gets the Voronoi cell edge around a site specified by the origin of a QuadEdge. The userData of the LineString is set to be the Coordinate of the site. This allows attaching external data associated with the site to this cell polygon.
- Parameters:
-
| qe | a quadedge originating at the cell site |
| geomFact | a factory for building the polygon |
- Returns:
- a polygon indicating the cell extent
Gets a List of LineStrings for the Voronoi cells of this triangulation. The userData of each LineString is set to be the Coordinate of the cell site. This allows easily associating external data associated with the sites to the cells.
- Parameters:
-
| geomFact | a geometry factory |
- Returns:
- a List of LineString
Gets the Voronoi cell around a site specified by the origin of a QuadEdge. The userData of the polygon is set to be the Coordinate of the site. This allows attaching external data associated with the site to this cell polygon.
- Parameters:
-
| qe | a quadedge originating at the cell site |
| geomFact | a factory for building the polygon |
- Returns:
- a polygon indicating the cell extent
Gets a List of Polygons for the Voronoi cells of this triangulation. The userData of each polygon is set to be the Coordinate of the cell site. This allows easily associating external data associated with the sites to the cells.
- Parameters:
-
| geomFact | a geometry factory |
- Returns:
- a List of Polygons
Gets the cells in the Voronoi diagram for this triangulation. The cells are returned as a GeometryCollection of Polygons The userData of each polygon is set to be the Coordinate of the cell site. This allows easily associating external data associated with the sites to the cells.
- Parameters:
-
| geomFact | a geometry factory |
- Returns:
- a GeometryCollection of Polygons
Gets the cells in the Voronoi diagram for this triangulation. The cells are returned as a GeometryCollection of LineStrings The userData of each polygon is set to be the Coordinate of the cell site. This allows easily associating external data associated with the sites to the cells.
- Parameters:
-
| geomFact | a geometry factory |
- Returns:
- a MultiLineString
QuadEdge& geos::triangulate::quadedge::QuadEdgeSubdivision::insertSite |
( |
const Vertex & |
v |
) |
|
Inserts a new site into the Subdivision, connecting it to the vertices of the containing triangle (or quadrilateral, if the split point falls on an existing edge).
This method does NOT maintain the Delaunay condition. If desired, this must be checked and enforced by the caller.
This method does NOT check if the inserted vertex falls on an edge. This must be checked by the caller, since this situation may cause erroneous triangulation
- Parameters:
-
- Returns:
- a new quad edge terminating in v
bool geos::triangulate::quadedge::QuadEdgeSubdivision::isFrameBorderEdge |
( |
const QuadEdge & |
e |
) |
const |
Tests whether a QuadEdge is an edge on the border of the frame facets and the internal facets. E.g. an edge which does not itself touch a frame vertex, but which touches an edge which does.
- Parameters:
-
- Returns:
- true if the edge is on the border of the frame
bool geos::triangulate::quadedge::QuadEdgeSubdivision::isFrameEdge |
( |
const QuadEdge & |
e |
) |
const |
Tests whether a QuadEdge is an edge incident on a frame triangle vertex.
- Parameters:
-
- Returns:
- true if the edge is connected to the frame triangle
bool geos::triangulate::quadedge::QuadEdgeSubdivision::isFrameVertex |
( |
const Vertex & |
v |
) |
const |
Tests whether a vertex is a vertex of the outer triangle.
- Parameters:
-
- Returns:
- true if the vertex is an outer triangle vertex
bool geos::triangulate::quadedge::QuadEdgeSubdivision::isOnEdge |
( |
const QuadEdge & |
e, |
|
|
const geom::Coordinate & |
p | |
|
) |
| | const |
Tests whether a Coordinate lies on a QuadEdge, up to a tolerance determined by the subdivision tolerance.
- Parameters:
-
- Returns:
- true if the vertex lies on the edge
bool geos::triangulate::quadedge::QuadEdgeSubdivision::isVertexOfEdge |
( |
const QuadEdge & |
e, |
|
|
const Vertex & |
v | |
|
) |
| | const |
Tests whether a Vertex is the start or end vertex of a QuadEdge, up to the subdivision tolerance distance.
- Parameters:
-
- Returns:
- true if the vertex is a endpoint of the edge
Locates the edge between the given vertices, if it exists in the subdivision.
- Parameters:
-
| p0 | a coordinate |
| p1 | another coordinate |
- Returns:
- the edge joining the coordinates, if present
-
null if no such edge exists
-
the caller _should not_ free the returned pointer
Finds a quadedge of a triangle containing a location specified by a Coordinate, if one exists.
- Parameters:
-
| p | the Coordinate to locate |
- Returns:
- a quadedge on the edge of a triangle which touches or contains the location
-
null if no such triangle exists. The returned pointer should not be freed be the caller.
QuadEdge* geos::triangulate::quadedge::QuadEdgeSubdivision::locate |
( |
const Vertex & |
v |
) |
const [inline] |
Finds a quadedge of a triangle containing a location specified by a Vertex, if one exists.
- Parameters:
-
- Returns:
- a quadedge on the edge of a triangle which touches or contains the location
-
null if no such triangle exists. The returned pointer should not be freed be the caller.
QuadEdge* geos::triangulate::quadedge::QuadEdgeSubdivision::locateFromEdge |
( |
const Vertex & |
v, |
|
|
const QuadEdge & |
startEdge | |
|
) |
| | const |
Locates an edge of a triangle which contains a location specified by a Vertex v. The edge returned has the property that either v is on e, or e is an edge of a triangle containing v. The search starts from startEdge amd proceeds on the general direction of v.
This locate algorithm relies on the subdivision being Delaunay. For non-Delaunay subdivisions, this may loop for ever.
- Parameters:
-
| v | the location to search for |
| startEdge | an edge of the subdivision to start searching at |
- Returns:
- a QuadEdge which contains v, or is on the edge of a triangle containing v
- Exceptions:
-
| LocateFailureException | if the location algorithm fails to converge in a reasonable number of iterations. The returned pointer should not be freed be the caller. |
virtual QuadEdge& geos::triangulate::quadedge::QuadEdgeSubdivision::makeEdge |
( |
const Vertex & |
o, |
|
|
const Vertex & |
d | |
|
) |
| | [virtual] |
Creates a new quadedge, recording it in the edges list.
- Parameters:
-
- Returns:
void geos::triangulate::quadedge::QuadEdgeSubdivision::remove |
( |
QuadEdge & |
e |
) |
|
Deletes a quadedge from the subdivision. Linked quadedges are updated to reflect the deletion.
- Parameters:
-
void geos::triangulate::quadedge::QuadEdgeSubdivision::setLocator |
( |
std::auto_ptr< QuadEdgeLocator > |
locator |
) |
[inline] |
Sets the QuadEdgeLocator to use for locating containing triangles in this subdivision.
- Parameters:
-
The documentation for this class was generated from the following file: