Triangulates all the polygons with more than three vertices of a gdb terrain database. More...

Static Public Member Functions
static bool	triangulateTerrain (DtTerrainDatabase *db)
	Converts all the polygon indirect nodes of db into triangle indirect nodes by applying a triangulation algorithm to each polygon node.
static DtTriangulationResult	triangulatePolygon (DtTerrainDatabase db, DtPolygonIndirect node, DtGroup *const parent)
	Triangulates the polygon defined by node.

Static Protected Member Functions
static double	kross (const DtVertexManager *mgr, int a, int b, int c)
	Returns the value of the z component of the cross product between the segments defined by the indexes ab and ac.
static bool	collinear (const DtVertexManager *mgr, int a, int b, int c)
	Determines whether the points at indexes a, b, and c are all collinear.
static bool	segmentInCone (const DtVertexManager *mgr, int v0, int v1, int vm, int vp)
	Checks whether the segment v0v1 is contained in the cone with vertex v0 and edges with directions (vm - vi) and (vp - vi)
static bool	between (const DtVertexManager *mgr, int a, int b, int c)
	Determines whether the point vb is between va and vc.
static bool	properIntersect (const DtVertexManager *mgr, int a, int b, int c, int d)
	Checks whether the segment va-vb properly intersects the segment vc-vd: They share a point interior to both segments.
static bool	intersect (const DtVertexManager *mgr, int a, int b, int c, int d)
	Checks whether the segment va-vb intersects with segment vc-vd: They intersect properly or one endpoint of one segment lies between the two endpoints of the other segment.
static bool	isDiagonal (const DtVertexManager *mgr, int numberOfVertices, std::vector< DtVertexID > &vertIds, int i0, int i1)
	Determines whether the segment defined by vi0 and vi1 is contained by the polygon vertIDs and does not fully intersect any of its edges.
static bool	isValidPoly (const DtPolygonIndirect *poly)
	Determines whether poly has a non-zero normal.
static bool	isFlatSurface (const DtPolygonIndirect *poly)
	Determines whether all the vertices inside poly are coplanar.
static void	printVerts (std::vector< DtVertexID > lst)
	Prints the contents of the list lst.
static void	triangulatePolygon (DtTerrainDatabase db, DtSurfaceID sid, const DtVertexManager mgr, DtGroup *const parent, std::vector< DtVertexID > &vertIds)
	Triangulates the polygon defined by vertIds.
static bool	alignPolygonToXYPlane (DtPolygonIndirect *poly, DtHomogeneousTransfMatrix &aMatrix)
	Projects the polygon poly onto the xy plane by aligning its normal with the z axis.
static void	transformPolygon (DtPolygonIndirect *poly, DtHomogeneousTransfMatrix &aMatrix)
	Applies the transformation aMatrix to the polygon node poly.

Static Protected Attributes
static const double	theErrorMargin

Detailed Description

Triangulates all the polygons with more than three vertices of a gdb terrain database.

The algorithmic used in this class is based on the theory presented in Computational Geometry in C (Joseph O'Rourke) - Chapter 1 Geometric Tools for Computer Graphics (Schneider) - Section 13.9 Computer Graphics (Foley & Van Dam) - p. 222 Notation: vi = vertex located at position i inside the vertex manager

Member Function Documentation

static bool DtTriangulator::triangulateTerrain ( DtTerrainDatabase * db )

static

Converts all the polygon indirect nodes of db into triangle indirect nodes by applying a triangulation algorithm to each polygon node.

The polygon node is removed from the database and transformed into 2+ triangle indirect nodes.

Parameters

db	- Terrain database to be triangulated

static DtTriangulationResult DtTriangulator::triangulatePolygon	(	DtTerrainDatabase *	db,
		DtPolygonIndirect *	node,
		DtGroup *const	parent
	)

static

Triangulates the polygon defined by node.

It creates an exact copy of the polygon but with triangles. This method creates and adds TRIANGLE_INDIRECT nodes into the terrain database. Each triangle is created with the surface Id sid.

Parameters

db	- (in) Terrain database where the nodes will be added
node	- (in) Polygon to be triangulated parent - (in) Parent of the node

Returns: DtPolygonTye indicating whether the polygon was successfully triangulated or not

static double DtTriangulator::kross	(	const DtVertexManager *	mgr,
		int	a,
		int	b,
		int	c
	)

staticprotected

Returns the value of the z component of the cross product between the segments defined by the indexes ab and ac.

Parameters

mgr	- (in) Vertex manager containing the actual vertices
a,b,c	- (in) Indexes of the vertices inside mgr, defining the segment

Returns: (abxac).z()

static bool DtTriangulator::collinear	(	const DtVertexManager *	mgr,
		int	a,
		int	b,
		int	c
	)

staticprotected

Determines whether the points at indexes a, b, and c are all collinear.

Parameters

mgr	- (in) Vertex manager containing the actual vertices
a,b,c	- (in) Indexes of the vertices inside the vertex manager

Returns: True if va, vb, and vc are collinear. False otherwise.

static bool DtTriangulator::segmentInCone	(	const DtVertexManager *	mgr,
		int	v0,
		int	v1,
		int	vm,
		int	vp
	)

staticprotected

Checks whether the segment v0v1 is contained in the cone with vertex v0 and edges with directions (vm - vi) and (vp - vi)

Parameters

mgr	- (in) Vertex manager containing the actual vertices
v0,v1	- (in) Indexes of the segment
vm	- (in) Index of the vertex located immediately before v0
vp	- (in) Index of the vertex located immediately after v0

Returns: True if the segment vov1 is within the cone.

static bool DtTriangulator::between	(	const DtVertexManager *	mgr,
		int	a,
		int	b,
		int	c
	)

staticprotected

Determines whether the point vb is between va and vc.

Parameters

mgr	- (in) Vertex manager containing the actual vertices
a,b,c	- (in) Indexes of the vertices to be tested for collinearity

Returns: False if the vertices are not collinear or if vb is not between va and vc.

static bool DtTriangulator::properIntersect	(	const DtVertexManager *	mgr,
		int	a,
		int	b,
		int	c,
		int	d
	)

staticprotected

Checks whether the segment va-vb properly intersects the segment vc-vd: They share a point interior to both segments.

Parameters

mgr	- (in) Vertex manager containing the actual vertices
a,b,c,d	- (in) Indexes of the vertices defining the segments to be tested

Returns: True if there is proper intersection between the segments.

static bool DtTriangulator::intersect	(	const DtVertexManager *	mgr,
		int	a,
		int	b,
		int	c,
		int	d
	)

staticprotected

Checks whether the segment va-vb intersects with segment vc-vd: They intersect properly or one endpoint of one segment lies between the two endpoints of the other segment.

Parameters

mgr	- (in) Vertex manager containing the actual vertices
a,b,c,d	- (in) Indexes of the vertices defining the segments to be tested

Returns: True if there

static bool DtTriangulator::isDiagonal	(	const DtVertexManager *	mgr,
		int	numberOfVertices,
		std::vector< DtVertexID > &	vertIds,
		int	i0,
		int	i1
	)

staticprotected

Determines whether the segment defined by vi0 and vi1 is contained by the polygon vertIDs and does not fully intersect any of its edges.

Parameters

mgr	- (in) Vertex manager containing the actual vertices
numberOfVertices	- (in) Size of vertIds
i0,i1	- (in) Indexes of the vertices defining the segment to be tested

static bool DtTriangulator::isValidPoly ( const DtPolygonIndirect * poly )

staticprotected

Determines whether poly has a non-zero normal.

Parameters

poly	- (in) Polygon to be tested

Returns: True if poly has a non zero normal.

static bool DtTriangulator::isFlatSurface ( const DtPolygonIndirect * poly )

staticprotected

Determines whether all the vertices inside poly are coplanar.

Parameters

poly	- (in) Polygon to be tested

Returns: True if all the vertices of the polygon are on the same plane.

static void DtTriangulator::printVerts ( std::vector< DtVertexID > lst )

staticprotected

Prints the contents of the list lst.

Parameters

lst	- (in) List of vertices to be printed

static void DtTriangulator::triangulatePolygon	(	DtTerrainDatabase *	db,
		DtSurfaceID	sid,
		const DtVertexManager *	mgr,
		DtGroup *const	parent,
		std::vector< DtVertexID > &	vertIds
	)

staticprotected

Triangulates the polygon defined by vertIds.

It creates an exact copy of the polygon but with triangles. This method creates and adds TRIANGLE_INDIRECT nodes into the terrain database. Each triangle is created with the surface Id sid.

Parameters

db	- (in) Terrain database where the nodes will be added
sid	- (in) Surface id of the new nodes
mgr	- (in) Vertex manager containing the actual vertices
vertIds	- (in) Vector containing the indexes that define the
parent	- (in) Parent associated with the polygon being triangulated polygon to be triangulated

static bool DtTriangulator::alignPolygonToXYPlane	(	DtPolygonIndirect *	poly,
		DtHomogeneousTransfMatrix &	aMatrix
	)

staticprotected

Projects the polygon poly onto the xy plane by aligning its normal with the z axis.

Parameters

poly	- (in) Polygon to align
aMatrix	- (out) Transformation matrix used to project the polygon

Returns: True if aMatrix is different from the identity matrix.

static void DtTriangulator::transformPolygon	(	DtPolygonIndirect *	poly,
		DtHomogeneousTransfMatrix &	aMatrix
	)

staticprotected

Applies the transformation aMatrix to the polygon node poly.

Parameters

poly	- (in) Polygon to transform
aMatrix	- (in) Transformation matrix to apply on the polygon

Member Data Documentation

const double DtTriangulator::theErrorMargin

staticprotected

The documentation for this class was generated from the following file:

include/gdb/triangulator.h

Static Public Member Functions

Static Protected Member Functions

Static Protected Attributes

Detailed Description

Member Function Documentation

Member Data Documentation