libsurf
Programmer's Documentation
libsurf
Programmer's Documentation
Mesh generation engine.
DnMesh implements generation of unstructured surface meshes using Delaunay triangulation. Both plane Delaunay triangulation and Chew's variant for curved surfaces are supported. For three-dimensional surfaces, Chew's algorithm yields vastly superior meshes, but puts stringent requirements on the initial state if used for refinement.
Note:* This is the legacy surface mesh generator still used in sumo but to be replaced by DelaunayCore in the future.
#include <dnmesh.h>
Public Member Functions | |
| DnMesh (SurfacePtr s, DnType t) | |
| create generator for surface s | |
| Vct3 | eval (Real u, Real v) const |
| evaluate the surface | |
| void | init (uint nu, uint nv) |
| initialize with an equidistant mesh spaced nu x nv | |
| void | init (const Vector &up, const Vector &vp) |
| initialize with structured mesh | |
| void | init (const PointGrid< 2 > &pg) |
| initialize with arbitrary point grid | |
| void | init (const PointGrid< 2 > &pg, Real maxstretch, uint kins=9) |
| initialize point grid and cascade to remove stretched triangles | |
| bool | initBoundary (const PointList< 2 > &pts) |
| start with (optionally constrained) boundary, return true on success | |
| bool | initPolygon (const PointList< 2 > &pts) |
| fill a polygonal boundary for initialization | |
| uint | importMesh (const PointList< 2 > &pts, const Indices &qtri) |
| import a triangular mesh | |
| uint | exportMesh (PointList< 2 > &pts, Indices &qtri) const |
| export a triangular mesh (2D) | |
| uint | exportMesh (PointList< 2 > &pp, PointList< 3 > &vtx, PointList< 3 > &nrm, Indices &qtri) const |
| export a triangular mesh (3D) | |
| uint | nvertices () const |
| current number of vertices | |
| uint | nedges () const |
| current number of edges | |
| uint | nfaces () const |
| current number of triangles | |
| uint | nAllTriangles () const |
| number of triangles, including invalid ones (!) | |
| const Vct2 & | parpos (uint i) const |
| access parametric vertex position | |
| const Vct3 & | position (uint i) const |
| access 3D space position of vertex i | |
| const Vct3 & | normal (uint i) const |
| access surface normal of vertex i | |
| const uint * | triangleVertices (uint k) const |
| access vertex indices of triangle k, may return 0 for invalid triangle | |
| void | switchMode (DnType t) |
| change triangulation mode (hope that you know what you are doing) | |
| uint | elimNeedles (Real maxstretch, Real maxphi) |
| does not work yet | |
| Indices | addConstraint (const PointList< 2 > &pts, bool allowSplit=false) |
| Add constrained segments, return indices of constrained vertices. More... | |
| void | markKinks (Real dphi) |
| constrain an edge if it separates components with a normal jump between them | |
| void | disableBoundarySplit () |
| disable splitting of boundary edges | |
| void | enableBoundarySplit () |
| enable splitting of boundary edges | |
| uint | insertVertex (const Vct2 &p, bool &onBoundary) |
| insert vertex, sustain Delaunay property | |
| uint | insertBoundaryVertex (const Vct2 &p, Real ptol=gmepsilon) |
| insert a point into a boundary edge | |
| uint | addHole (const Vct2 &p) |
| place a hole at p and remove affected triangles | |
| void | destretch (uint nmax, Real maxstretch) |
| remove stretched triangles | |
| uint | refine (const DnRefineCriterion &c) |
| refine according to criteria (queue-based procedure) | |
| void | iterativeRefine (const DnRefineCriterion &c) |
| refine according to criteria (plain loop) | |
| void | refineAround (const Indices &vlist, const DnRefineCriterion &c) |
| split triangles near vertices in vlist | |
| void | smooth (uint niter=1, Real omega=1.0) |
| plain laplacian smoothing (all unconstrained vertices) | |
| void | smooth (const Indices &idx, uint niter, Real omega=1.0) |
| smooth using vertex subset | |
| void | smoothStretched (Real maxstretch) |
| smooth only vertices in stretched triangles | |
| void | smoothStretched (Real maxstretch, std::vector< BndRect > &bxs) |
| smooth stretched inside boxes only | |
| XmlElement | toXml () const |
| write 3D mesh to xml representation (MeshFields) | |
| XmlElement | pToXml () const |
| parameter space mesh to xml | |
| void | fixate () |
| recompute all connectivity | |
| void | setAbortFlag (bool flag) |
| set interruption flag to stop refinement | |
| void | cleanup (Real xyzt, Real uvt) |
| merge vertices closer than threshold | |
| const std::string & | lastError () const |
| access error message | |
Private Member Functions | |
| uint | addEdge (uint a, uint b) |
| add edge to triangulation, return index (no connectivity updates) | |
| uint | addTriangle (uint a, uint b, uint c) |
| add triangle to triangulation, return index (no connectivity updates) | |
| void | addQuad (uint a, uint b, uint c, uint d) |
| try to add two triangles for the quad a-d, intelligently | |
| void | fixDirection (DnTriangle &t) |
| fix direction of triangle normal | |
| uint | findEdgeSorted (uint a, uint b) const |
| find edge index, requires sorted edge array | |
| uint | findEdgeTopo (uint a, uint b) const |
| find edge index by topological search | |
| bool | canFlip (uint i) const |
| check if edge may be flipped | |
| bool | isKink (uint i) const |
| check if edge is on kink | |
| bool | canSplit (uint i) const |
| check if edge may be split | |
| void | forbidFlip (uint i) |
| register edge i as non-flippable | |
| void | forbidSplit (uint i) |
| register edge i as non-flippable | |
| int | locateTriangle (const Vct2 &p, uint vnear, uint &ti) const |
| locate triangle which contains position vertex p (2D algorithm) | |
| int | locateTriangle (uint ni, uint vnear, uint &ti) const |
| locate triangle which contains vertex ni (flexible algorithm) | |
| void | killTriangle (uint ti) |
| delete triangle, detach from vertices | |
| void | killEdge (uint ei) |
| delete edge (no connectivity updates) | |
| void | splitTriangle (uint ti, uint ni) |
| split one triangle into three | |
| bool | splitEdge (uint ei, uint ni) |
| split two triangles into four | |
| bool | refineEdge (uint ei, Real minlen) |
| insert new vertex at midpoint if possible | |
| uint | findDivider (uint ei, Real minlen) |
| find point to insert when refining edge ei | |
| bool | refineTriangle (uint tix, Real mxs, Real minlen) |
| determine if and how to refine triangle t | |
| void | smoothVertex (uint v) |
| move v to its barycenter, if legal | |
| bool | flipEdge (uint ei) |
| flip edge | |
| bool | legalizeEdge (uint ei, uint v) |
| recusively flip edges to establish Delauny property | |
| uint | enforceEdge (uint a, uint b) |
| make sure that edge a,b occurs in triangulation | |
| uint | findNeighborhood (uint ei, uint v[4], uint nbe[4], uint nbf[2]) const |
| compute edge neighborhood | |
| void | collectNbEdges (uint i, Indices &edg, bool allEdges=false) const |
| collect all edges which run into vertex i | |
| uint | recursiveErase (uint ti) |
| kill triangles starting from ti until constrained edges are encountered | |
| uint | carveHole (uint ti) |
| collect triangles to erase | |
| uint | insertSegment (uint a, uint b) |
| insert edge which cannot be inserted using edge flips alone | |
| Real | orientation (uint a, uint b, uint c) const |
| suitable orientation test sepending on mesh type | |
| Real | pOrientation (uint a, uint b, uint c) const |
| orientation test in 2D | |
| Real | sOrientation (uint a, uint b, uint c) const |
| orientation test in 3D | |
| int | isInside (uint ti, uint ni) const |
| test if vertex ni is inside triangle ti | |
| int | sIsInside (uint ti, uint ni) const |
| test if vertex ni is inside triangle ti | |
| int | sIsOnBoundaryEdge (uint ti, uint ni) const |
| special case of vertex on wrapped boundary | |
| int | pIsInside (uint ti, uint ni) const |
| test if vertex ni is inside triangle ti | |
| bool | intersects (uint ei, uint a, uint b) const |
| test if edge ei intersects line a-b | |
| bool | sIntersects (uint ei, uint a, uint b) const |
| test if a and b lie on different side of ei (intersection) | |
| bool | triangulatePolygon (uint ei, const Indices &v) |
| triangulate the polygon above the edge ei | |
| void | classify (uint ti, Real maxstretch, DnTriangleShape &shp) const |
| compute edge lengths, return triangle area | |
| bool | collapseEdge (uint eshort) |
| try to merge source and target of eshort | |
| void | fuseVertices (uint vdrop, uint vkeep) |
| change vdrop to vkeep in all faces connected to vdrop | |
| bool | destroyHat (uint ti, uint elong) |
| refine a triangle with one long side and a large angle | |
| bool | isConvexSet (uint v[4]) const |
| check if the neighborhood v is convex | |
| void | centerVertex (uint i, Real omega=1.0) |
| displace a vertex to the barycenter of its ring-1 neighborhood | |
| void | constructPolygon (uint v, Indices &ip) const |
| collect the surrounding polygon for an interior point | |
| bool | ptInPolygon (const Vct2 &pt, const Indices &ip) const |
| check if pt is inside polygon determined by ip | |
| bool | vertexCanMove (uint v, const Vct2 &pt) const |
| check if vertex v can be moved to pt without tangling the mesh | |
| uint | checkConnectivity (uint v, Indices &nbv) const |
| debugging : check local connectivity for consistency (aborts on error) | |
| void | clear () |
| delete everything | |
| uint | nntriangles () |
| prepare list of changed triangles | |
| uint | nnedges () |
| prepare list of changed edges | |
Private Attributes | |
| DnType | type |
| Delaunay algorithm used. | |
| SurfacePtr | psf |
| underlying continuous surface | |
| DnVertexArray | vertices |
| vertex array | |
| DnEdgeArray | edges |
| edge array | |
| DnTriangleArray | triangles |
| triangle array | |
| RSearchTree | btree |
| point search tree | |
| Indices | iDeadEdges |
| dead edges and triangles | |
| Indices | iDeadTriangles |
| Indices | iNoFlip |
| edges which may not be flipped or split | |
| Indices | iKinkEdge |
| Indices | iNoSplit |
| Indices | newEdges |
| newly created edges or modified triangles | |
| Indices | newTriangles |
| bool | uwrap |
| flag which indicates if geometry is wrapped in u-direction | |
| bool | depinsert |
| bool | nowrefining |
| bool | bAbort |
| refinement is interrupted if this flag is set to true | |
| std::string | errmsg |
| error message | |
| Indices DnMesh::addConstraint | ( | const PointList< 2 > & | pts, |
| bool | allowSplit = false |
||
| ) |
Add constrained segments, return indices of constrained vertices.
This method returns an empty set if insertion failed because of colliding constraints.
1.8.5