diff --git a/src/polygon.h b/src/polygon.h index 66023eb2..cf0f3228 100644 --- a/src/polygon.h +++ b/src/polygon.h @@ -131,6 +131,7 @@ public: void FindPointWithMinX(); Vector AnyEdgeMidpoint() const; + bool IsEmptyTriangle(int ap, int bp, int cp, double scaledEPS) const; bool IsEar(int bp, double scaledEps) const; bool BridgeToContour(SContour *sc, SEdgeList *el, List *vl); void ClipEarInto(SMesh *m, int bp, double scaledEps); diff --git a/src/srf/triangulate.cpp b/src/srf/triangulate.cpp index e6cd6e49..a9fce6c7 100644 --- a/src/srf/triangulate.cpp +++ b/src/srf/triangulate.cpp @@ -213,6 +213,41 @@ haveEdge: return true; } +bool SContour::IsEmptyTriangle(int ap, int bp, int cp, double scaledEPS) const { + + STriangle tr = {}; + tr.a = l[ap].p; + tr.b = l[bp].p; + tr.c = l[cp].p; + + // Accelerate with an axis-aligned bounding box test + Vector maxv = tr.a, minv = tr.a; + (tr.b).MakeMaxMin(&maxv, &minv); + (tr.c).MakeMaxMin(&maxv, &minv); + + Vector n = Vector::From(0, 0, -1); + + int i; + for(i = 0; i < l.n; i++) { + if(i == ap || i == bp || i == cp) continue; + + Vector p = l[i].p; + if(p.OutsideAndNotOn(maxv, minv)) continue; + + // A point on the edge of the triangle is considered to be inside, + // and therefore makes it a non-ear; but a point on the vertex is + // "outside", since that's necessary to make bridges work. + if(p.EqualsExactly(tr.a)) continue; + if(p.EqualsExactly(tr.b)) continue; + if(p.EqualsExactly(tr.c)) continue; + + if(tr.ContainsPointProjd(n, p)) { + return false; + } + } + return true; +} + bool SContour::IsEar(int bp, double scaledEps) const { int ap = WRAP(bp-1, l.n), cp = WRAP(bp+1, l.n); @@ -308,6 +343,71 @@ void SContour::UvTriangulateInto(SMesh *m, SSurface *srf) { } l.RemoveTagged(); + // Handle simple triangle fans all at once. This pass is optional. + if(srf->degm == 1 && srf->degn == 1) { + l.ClearTags(); + int j=0; + int pstart = 0; + double elen = -1.0; + double oldspan = 0.0; + for(i = 1; i < l.n; i++) { + Vector ab = l[i].p.Minus(l[i-1].p); + // first time just measure the segment + if (elen < 0.0) { + elen = ab.Dot(ab); + oldspan = elen; + j = 1; + continue; + } + // check for consecutive segments of similar size which are also + // ears and where the group forms a convex ear + bool end = false; + double ratio = ab.Dot(ab) / elen; + if ((ratio < 0.25) || (ratio > 4.0)) end = true; + + double slen = l[pstart].p.Minus(l[i].p).MagSquared(); + if (slen < oldspan) end = true; + + if (!IsEar(i-1, scaledEps) ) end = true; +// if ((j>0) && !IsEar(pstart, i-1, i, scaledEps)) end = true; + if ((j>0) && !IsEmptyTriangle(pstart, i-1, i, scaledEps)) end = true; + // the new segment is valid so add to the fan + if (!end) { + j++; + oldspan = slen; + } + // we need to stop at the end of polygon but may still + if (i == l.n-1) { + end = true; + } + if (end) { // triangulate the fan and tag the verticies + if (j > 3) { + Vector center = l[pstart+1].p.Plus(l[pstart+j-1].p).ScaledBy(0.5); + for (int x=0; xAddTriangle(&tr); + } + for (int x=1; xAddTriangle(&tr); + } + pstart = i-1; + elen = ab.Dot(ab); + oldspan = elen; + j = 1; + } + } + l.RemoveTagged(); + } // end optional fan creation pass + bool toggle = false; while(l.n > 3) { int bestEar = -1;