コード例 #1
0
ファイル: MinimalHoleFill.cs プロジェクト: CallAndGus/ViRGIS
        public bool Apply()
        {
            // do a simple fill
            SimpleHoleFiller simplefill = new SimpleHoleFiller(Mesh, FillLoop);
            int  fill_gid = Mesh.AllocateTriangleGroup();
            bool bOK      = simplefill.Fill(fill_gid);

            if (bOK == false)
            {
                return(false);
            }

            if (FillLoop.Vertices.Length <= 3)
            {
                FillTriangles = simplefill.NewTriangles;
                FillVertices  = new int[0];
                return(true);
            }

            // extract the simple fill mesh as a submesh, via RegionOperator, so we can backsub later
            HashSet <int> intial_fill_tris = new HashSet <int>(simplefill.NewTriangles);

            regionop = new RegionOperator(Mesh, simplefill.NewTriangles,
                                          (submesh) => { submesh.ComputeTriMaps = true; });
            fillmesh = regionop.Region.SubMesh;

            // for each boundary vertex, compute the exterior angle sum
            // we will use this to compute gaussian curvature later
            boundaryv           = new HashSet <int>(MeshIterators.BoundaryEdgeVertices(fillmesh));
            exterior_angle_sums = new Dictionary <int, double>();
            if (IgnoreBoundaryTriangles == false)
            {
                foreach (int sub_vid in boundaryv)
                {
                    double angle_sum = 0;
                    int    base_vid  = regionop.Region.MapVertexToBaseMesh(sub_vid);
                    foreach (int tid in regionop.BaseMesh.VtxTrianglesItr(base_vid))
                    {
                        if (intial_fill_tris.Contains(tid) == false)
                        {
                            Index3i et  = regionop.BaseMesh.GetTriangle(tid);
                            int     idx = IndexUtil.find_tri_index(base_vid, ref et);
                            angle_sum += regionop.BaseMesh.GetTriInternalAngleR(tid, idx);
                        }
                    }
                    exterior_angle_sums[sub_vid] = angle_sum;
                }
            }


            // try to guess a reasonable edge length that will give us enough geometry to work with in simplify pass
            double loop_mine, loop_maxe, loop_avge, fill_mine, fill_maxe, fill_avge;

            MeshQueries.EdgeLengthStatsFromEdges(Mesh, FillLoop.Edges, out loop_mine, out loop_maxe, out loop_avge);
            MeshQueries.EdgeLengthStats(fillmesh, out fill_mine, out fill_maxe, out fill_avge);
            double remesh_target_len = loop_avge;

            if (fill_maxe / remesh_target_len > 10)
            {
                remesh_target_len = fill_maxe / 10;
            }
            //double remesh_target_len = Math.Min(loop_avge, fill_avge / 4);

            // remesh up to target edge length, ideally gives us some triangles to work with
            RemesherPro remesh1 = new RemesherPro(fillmesh);

            remesh1.SmoothSpeedT = 1.0;
            MeshConstraintUtil.FixAllBoundaryEdges(remesh1);
            //remesh1.SetTargetEdgeLength(remesh_target_len / 2);       // would this speed things up? on large regions?
            //remesh1.FastestRemesh();
            remesh1.SetTargetEdgeLength(remesh_target_len);
            remesh1.FastestRemesh();

            /*
             * first round: collapse to minimal mesh, while flipping to try to
             * get to ballpark minimal mesh. We stop these passes as soon as
             * we have done two rounds where we couldn't do another collapse
             *
             * This is the most unstable part of the algorithm because there
             * are strong ordering effects. maybe we could sort the edges somehow??
             */

            int zero_collapse_passes = 0;
            int collapse_passes      = 0;

            while (collapse_passes++ < 20 && zero_collapse_passes < 2)
            {
                // collapse pass
                int NE        = fillmesh.MaxEdgeID;
                int collapses = 0;
                for (int ei = 0; ei < NE; ++ei)
                {
                    if (fillmesh.IsEdge(ei) == false || fillmesh.IsBoundaryEdge(ei))
                    {
                        continue;
                    }
                    Index2i ev = fillmesh.GetEdgeV(ei);
                    bool    a_bdry = boundaryv.Contains(ev.a), b_bdry = boundaryv.Contains(ev.b);
                    if (a_bdry && b_bdry)
                    {
                        continue;
                    }
                    int      keepv  = (a_bdry) ? ev.a : ev.b;
                    int      otherv = (keepv == ev.a) ? ev.b : ev.a;
                    Vector3d newv   = fillmesh.GetVertex(keepv);
                    if (MeshUtil.CheckIfCollapseCreatesFlip(fillmesh, ei, newv))
                    {
                        continue;
                    }
                    DMesh3.EdgeCollapseInfo info;
                    MeshResult result = fillmesh.CollapseEdge(keepv, otherv, out info);
                    if (result == MeshResult.Ok)
                    {
                        collapses++;
                    }
                }
                if (collapses == 0)
                {
                    zero_collapse_passes++;
                }
                else
                {
                    zero_collapse_passes = 0;
                }

                // flip pass. we flip in these cases:
                //  1) if angle between current triangles is too small (slightly more than 90 degrees, currently)
                //  2) if angle between flipped triangles is smaller than between current triangles
                //  3) if flipped edge length is shorter *and* such a flip won't flip the normal
                NE = fillmesh.MaxEdgeID;
                Vector3d n1, n2, on1, on2;
                for (int ei = 0; ei < NE; ++ei)
                {
                    if (fillmesh.IsEdge(ei) == false || fillmesh.IsBoundaryEdge(ei))
                    {
                        continue;
                    }
                    bool do_flip = false;

                    Index2i ev = fillmesh.GetEdgeV(ei);
                    MeshUtil.GetEdgeFlipNormals(fillmesh, ei, out n1, out n2, out on1, out on2);
                    double dot_cur  = n1.Dot(n2);
                    double dot_flip = on1.Dot(on2);
                    if (n1.Dot(n2) < 0.1 || dot_flip > dot_cur + MathUtil.Epsilonf)
                    {
                        do_flip = true;
                    }

                    if (do_flip == false)
                    {
                        Index2i otherv   = fillmesh.GetEdgeOpposingV(ei);
                        double  len_e    = fillmesh.GetVertex(ev.a).Distance(fillmesh.GetVertex(ev.b));
                        double  len_flip = fillmesh.GetVertex(otherv.a).Distance(fillmesh.GetVertex(otherv.b));
                        if (len_flip < len_e)
                        {
                            if (MeshUtil.CheckIfEdgeFlipCreatesFlip(fillmesh, ei) == false)
                            {
                                do_flip = true;
                            }
                        }
                    }

                    if (do_flip)
                    {
                        DMesh3.EdgeFlipInfo info;
                        MeshResult          result = fillmesh.FlipEdge(ei, out info);
                    }
                }
            }

            // Sometimes, for some reason, we have a remaining interior vertex (have only ever seen one?)
            // Try to force removal of such vertices, even if it makes ugly mesh
            remove_remaining_interior_verts();


            // enable/disable passes.
            bool DO_FLATTER_PASS   = true;
            bool DO_CURVATURE_PASS = OptimizeDevelopability && true;
            bool DO_AREA_PASS      = OptimizeDevelopability && OptimizeTriangles && true;


            /*
             * In this pass we repeat the flipping iterations from the previous pass.
             *
             * Note that because of the always-flip-if-dot-is-small case (commented),
             * this pass will frequently not converge, as some number of edges will
             * be able to flip back and forth (because neither has large enough dot).
             * This is not ideal, but also, if we remove this behavior, then we
             * generally get worse fills. This case basically introduces a sort of
             * randomization factor that lets us escape local minima...
             *
             */

            HashSet <int> remaining_edges = new HashSet <int>(fillmesh.EdgeIndices());
            HashSet <int> updated_edges   = new HashSet <int>();

            int flatter_passes    = 0;
            int zero_flips_passes = 0;

            while (flatter_passes++ < 40 && zero_flips_passes < 2 && remaining_edges.Count() > 0 && DO_FLATTER_PASS)
            {
                zero_flips_passes++;
                foreach (int ei in remaining_edges)
                {
                    if (fillmesh.IsBoundaryEdge(ei))
                    {
                        continue;
                    }

                    bool do_flip = false;

                    Index2i  ev = fillmesh.GetEdgeV(ei);
                    Vector3d n1, n2, on1, on2;
                    MeshUtil.GetEdgeFlipNormals(fillmesh, ei, out n1, out n2, out on1, out on2);
                    double dot_cur  = n1.Dot(n2);
                    double dot_flip = on1.Dot(on2);
                    if (flatter_passes < 20 && dot_cur < 0.1)   // this check causes oscillatory behavior
                    {
                        do_flip = true;
                    }
                    if (dot_flip > dot_cur + MathUtil.Epsilonf)
                    {
                        do_flip = true;
                    }

                    if (do_flip)
                    {
                        DMesh3.EdgeFlipInfo info;
                        MeshResult          result = fillmesh.FlipEdge(ei, out info);
                        if (result == MeshResult.Ok)
                        {
                            zero_flips_passes = 0;
                            add_all_edges(ei, updated_edges);
                        }
                    }
                }

                var tmp = remaining_edges;
                remaining_edges = updated_edges;
                updated_edges   = tmp; updated_edges.Clear();
            }


            int curvature_passes = 0;

            if (DO_CURVATURE_PASS)
            {
                curvatures = new double[fillmesh.MaxVertexID];
                foreach (int vid in fillmesh.VertexIndices())
                {
                    update_curvature(vid);
                }

                remaining_edges = new HashSet <int>(fillmesh.EdgeIndices());
                updated_edges   = new HashSet <int>();

                /*
                 *  In this pass we try to minimize gaussian curvature at all the vertices.
                 *  This will recover sharp edges, etc, and do lots of good stuff.
                 *  However, this pass will not make much progress if we are not already
                 *  relatively close to a minimal mesh, so it really relies on the previous
                 *  passes getting us in the ballpark.
                 */
                while (curvature_passes++ < 40 && remaining_edges.Count() > 0 && DO_CURVATURE_PASS)
                {
                    foreach (int ei in remaining_edges)
                    {
                        if (fillmesh.IsBoundaryEdge(ei))
                        {
                            continue;
                        }

                        Index2i ev = fillmesh.GetEdgeV(ei);
                        Index2i ov = fillmesh.GetEdgeOpposingV(ei);

                        int find_other = fillmesh.FindEdge(ov.a, ov.b);
                        if (find_other != DMesh3.InvalidID)
                        {
                            continue;
                        }

                        double total_curv_cur = curvature_metric_cached(ev.a, ev.b, ov.a, ov.b);
                        if (total_curv_cur < MathUtil.ZeroTolerancef)
                        {
                            continue;
                        }

                        DMesh3.EdgeFlipInfo info;
                        MeshResult          result = fillmesh.FlipEdge(ei, out info);
                        if (result != MeshResult.Ok)
                        {
                            continue;
                        }

                        double total_curv_flip = curvature_metric_eval(ev.a, ev.b, ov.a, ov.b);

                        bool keep_flip = total_curv_flip < total_curv_cur - MathUtil.ZeroTolerancef;
                        if (keep_flip == false)
                        {
                            result = fillmesh.FlipEdge(ei, out info);
                        }
                        else
                        {
                            update_curvature(ev.a); update_curvature(ev.b);
                            update_curvature(ov.a); update_curvature(ov.b);
                            add_all_edges(ei, updated_edges);
                        }
                    }
                    var tmp = remaining_edges;
                    remaining_edges = updated_edges;
                    updated_edges   = tmp; updated_edges.Clear();
                }
            }
            //System.Console.WriteLine("collapse {0}   flatter {1}   curvature {2}", collapse_passes, flatter_passes, curvature_passes);

            /*
             * In this final pass, we try to improve triangle quality. We flip if
             * the flipped triangles have better total aspect ratio, and the
             * curvature doesn't change **too** much. The .DevelopabilityTolerance
             * parameter determines what is "too much" curvature change.
             */
            if (DO_AREA_PASS)
            {
                remaining_edges = new HashSet <int>(fillmesh.EdgeIndices());
                updated_edges   = new HashSet <int>();
                int area_passes = 0;
                while (remaining_edges.Count() > 0 && area_passes < 20)
                {
                    area_passes++;
                    foreach (int ei in remaining_edges)
                    {
                        if (fillmesh.IsBoundaryEdge(ei))
                        {
                            continue;
                        }

                        Index2i ev = fillmesh.GetEdgeV(ei);
                        Index2i ov = fillmesh.GetEdgeOpposingV(ei);

                        int find_other = fillmesh.FindEdge(ov.a, ov.b);
                        if (find_other != DMesh3.InvalidID)
                        {
                            continue;
                        }

                        double total_curv_cur = curvature_metric_cached(ev.a, ev.b, ov.a, ov.b);

                        double a = aspect_metric(ei);
                        if (a > 1)
                        {
                            continue;
                        }

                        DMesh3.EdgeFlipInfo info;
                        MeshResult          result = fillmesh.FlipEdge(ei, out info);
                        if (result != MeshResult.Ok)
                        {
                            continue;
                        }

                        double total_curv_flip = curvature_metric_eval(ev.a, ev.b, ov.a, ov.b);

                        bool keep_flip = Math.Abs(total_curv_cur - total_curv_flip) < DevelopabilityTolerance;
                        if (keep_flip == false)
                        {
                            result = fillmesh.FlipEdge(ei, out info);
                        }
                        else
                        {
                            update_curvature(ev.a); update_curvature(ev.b);
                            update_curvature(ov.a); update_curvature(ov.b);
                            add_all_edges(ei, updated_edges);
                        }
                    }
                    var tmp = remaining_edges;
                    remaining_edges = updated_edges;
                    updated_edges   = tmp; updated_edges.Clear();
                }
            }


            regionop.BackPropropagate();
            FillTriangles = regionop.CurrentBaseTriangles;
            FillVertices  = regionop.CurrentBaseInteriorVertices().ToArray();

            return(true);
        }