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Add vertexes to curve intersection list in addition to surface intersections. 

Sometimes a vertex can be used to split a curve where surface intersections can't. Those unsplit curves can cause boolean failures.
pull/760/head
phkahler 2020-10-14 20:27:56 -04:00
parent 6b5936b2f6
commit ab10e38d44
1 changed files with 47 additions and 3 deletions
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50
src/srf/boolean.cpp
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@ -20,6 +20,32 @@ void SShell::MakeFromIntersectionOf(SShell *a, SShell *b) {
MakeFromBoolean(a, b, SSurface::CombineAs::INTERSECTION);
}
// We will be inserting existing verticies into curves to split them
// todo: this is only using the ends of exact curves, and it is only
// using them to split existing curves, not new intersections.
// It resolves some issues but we could do better. We will need to
// reorder things so the surface intersection curves exist prior to
// splitting any curves at all in order to have their verticies too.
// Better still would be to get curve/surface intersection to work
// more reliably at the edges - maybe do curve/curve tests as part
// of the curve-surface intersection test.
static void FindVertsOnCurve(List<SInter> *l, const SCurve *curve, SShell *sh) {
for(auto sc : sh->curve) {
if(!sc.isExact) continue;
for(int i=0; i<2; i++) {
Vector pt = sc.exact.ctrl[ i==0 ? 0 : sc.exact.deg ];
double t;
curve->exact.ClosestPointTo(pt, &t, /*must converge=*/ false);
double d = pt.Minus(curve->exact.PointAt(t)).Magnitude();
if((t>LENGTH_EPS) && (t<(1.0-LENGTH_EPS)) && (d < LENGTH_EPS)) {
SInter inter;
inter.p = pt;
l->Add(&inter);
}
}
}
}
//-----------------------------------------------------------------------------
// Take our original pwl curve. Wherever an edge intersects a surface within
// either agnstA or agnstB, split the piecewise linear element. Then refine
@ -35,12 +61,19 @@ SCurve SCurve::MakeCopySplitAgainst(SShell *agnstA, SShell *agnstB,
ret = *this;
ret.pts = {};
// First find any vertex that lies on our curve.
List<SInter> vertpts = {};
if(agnstA)
FindVertsOnCurve(&vertpts, this, agnstA);
if(agnstB)
FindVertsOnCurve(&vertpts, this, agnstB);
const SCurvePt *p = pts.First();
ssassert(p != NULL, "Cannot split an empty curve");
SCurvePt prev = *p;
ret.pts.Add(p);
p = pts.NextAfter(p);
for(; p; p = pts.NextAfter(p)) {
List<SInter> il = {};
@ -100,12 +133,22 @@ SCurve SCurve::MakeCopySplitAgainst(SShell *agnstA, SShell *agnstB,
pi->p = (pi->srf)->PointAt(puv);
}
il.RemoveTagged();
}
// Now add any vertex that is on this segment
const Vector lineStart = prev.p;
const Vector lineDirection = (p->p).Minus(prev.p);
for(auto vtx : vertpts) {
double t = (vtx.p.Minus(lineStart)).DivProjected(lineDirection);
if((0.0 < t) && (t < 1.0)) {
il.Add(&vtx);
}
}
if(!il.IsEmpty()) {
SInter *pi;
// And now sort them in order along the line. Note that we must
// do that after refining, in case the refining would make two
// points switch places.
const Vector lineStart = prev.p;
const Vector lineDirection = (p->p).Minus(prev.p);
std::sort(il.begin(), il.end(), [&](const SInter &a, const SInter &b) {
double ta = (a.p.Minus(lineStart)).DivProjected(lineDirection);
double tb = (b.p.Minus(lineStart)).DivProjected(lineDirection);
@ -133,6 +176,7 @@ SCurve SCurve::MakeCopySplitAgainst(SShell *agnstA, SShell *agnstB,
ret.pts.Add(p);
prev = *p;
}
vertpts.Clear();
return ret;
}