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.

Static Public Member Functions
static bool	triangulateTerrain (DtTerrainDatabase *db)

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

Static Protected Member Functions
static double	kross (const DtVertexManager *mgr, int a, int b, int c)

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

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

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

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

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

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

static bool	isValidPoly (const DtPolygonIndirect *poly)

static bool	isFlatSurface (const DtPolygonIndirect *poly)

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

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

static bool	alignPolygonToXYPlane (DtPolygonIndirect *poly, DtHomogeneousTransformMatrix &aMatrix)

static void	transformPolygon (DtPolygonIndirect *poly, DtHomogeneousTransformMatrix &aMatrix)

Static Protected Attributes
static const double	theErrorMargin

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,
		DtHomogeneousTransformMatrix &	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,
		DtHomogeneousTransformMatrix &	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:

/data/exports/nrhent7-1/nightly/docs/vrForces.vrf5-2-branch/include/gdb/triangulator.h

Static Public Member Functions

Static Protected Member Functions

Static Protected Attributes

Member Function Documentation

Member Data Documentation