C++ SSurface::MakeEdgesInto方法代码示例

//-----------------------------------------------------------------------------
// In our shell, find all surfaces that are coincident with the prototype
// surface (with same or opposite normal, as specified), and copy all of
// their trim polygons into el. The edges are returned in uv coordinates for
// the prototype surface.
//-----------------------------------------------------------------------------
void SShell::MakeCoincidentEdgesInto(SSurface *proto, bool sameNormal,
                                     SEdgeList *el, SShell *useCurvesFrom)
{
    SSurface *ss;
    for(ss = surface.First(); ss; ss = surface.NextAfter(ss)) {
        if(proto->CoincidentWith(ss, sameNormal)) {
            ss->MakeEdgesInto(this, el, SSurface::MakeAs::XYZ, useCurvesFrom);
        }
    }

    SEdge *se;
    for(se = el->l.First(); se; se = el->l.NextAfter(se)) {
        double ua, va, ub, vb;
        proto->ClosestPointTo(se->a, &ua, &va);
        proto->ClosestPointTo(se->b, &ub, &vb);

        if(sameNormal) {
            se->a = Vector::From(ua, va, 0);
            se->b = Vector::From(ub, vb, 0);
        } else {
            // Flip normal, so flip all edge directions
            se->b = Vector::From(ua, va, 0);
            se->a = Vector::From(ub, vb, 0);
        }
    }
}

void SShell::MakeEdgesInto(SEdgeList *sel) {
    SSurface *s;
    for(s = surface.First(); s; s = surface.NextAfter(s)) {
        s->MakeEdgesInto(this, sel, SSurface::AS_XYZ);
    }
}

//-----------------------------------------------------------------------------
// Trim this surface against the specified shell, in the way that's appropriate
// for the specified Boolean operation type (and which operand we are). We
// also need a pointer to the shell that contains our own surface, since that
// contains our original trim curves.
//-----------------------------------------------------------------------------
SSurface SSurface::MakeCopyTrimAgainst(SShell *parent,
                                       SShell *sha, SShell *shb,
                                       SShell *into,
                                       int type)
{
    bool opA = (parent == sha);
    SShell *agnst = opA ? shb : sha;

    SSurface ret;
    // The returned surface is identical, just the trim curves change
    ret = *this;
    ret.trim = {};

    // First, build a list of the existing trim curves; update them to use
    // the split curves.
    STrimBy *stb;
    for(stb = trim.First(); stb; stb = trim.NextAfter(stb)) {
        STrimBy stn = *stb;
        stn.curve = (parent->curve.FindById(stn.curve))->newH;
        ret.trim.Add(&stn);
    }

    if(type == SShell::AS_DIFFERENCE && !opA) {
        // The second operand of a Boolean difference gets turned inside out
        ret.Reverse();
    }

    // Build up our original trim polygon; remember the coordinates could
    // be changed if we just flipped the surface normal, and we are using
    // the split curves (not the original curves).
    SEdgeList orig = {};
    ret.MakeEdgesInto(into, &orig, AS_UV);
    ret.trim.Clear();
    // which means that we can't necessarily use the old BSP...
    SBspUv *origBsp = SBspUv::From(&orig, &ret);

    // And now intersect the other shell against us
    SEdgeList inter = {};

    SSurface *ss;
    for(ss = agnst->surface.First(); ss; ss = agnst->surface.NextAfter(ss)) {
        SCurve *sc;
        for(sc = into->curve.First(); sc; sc = into->curve.NextAfter(sc)) {
            if(sc->source != SCurve::FROM_INTERSECTION) continue;
            if(opA) {
                if(sc->surfA.v != h.v || sc->surfB.v != ss->h.v) continue;
            } else {
                if(sc->surfB.v != h.v || sc->surfA.v != ss->h.v) continue;
            }

            int i;
            for(i = 1; i < sc->pts.n; i++) {
                Vector a = sc->pts.elem[i-1].p,
                       b = sc->pts.elem[i].p;

                Point2d auv, buv;
                ss->ClosestPointTo(a, &(auv.x), &(auv.y));
                ss->ClosestPointTo(b, &(buv.x), &(buv.y));

                int c = (ss->bsp) ? ss->bsp->ClassifyEdge(auv, buv, ss) : SBspUv::OUTSIDE;
                if(c != SBspUv::OUTSIDE) {
                    Vector ta = Vector::From(0, 0, 0);
                    Vector tb = Vector::From(0, 0, 0);
                    ret.ClosestPointTo(a, &(ta.x), &(ta.y));
                    ret.ClosestPointTo(b, &(tb.x), &(tb.y));

                    Vector tn = ret.NormalAt(ta.x, ta.y);
                    Vector sn = ss->NormalAt(auv.x, auv.y);

                    // We are subtracting the portion of our surface that
                    // lies in the shell, so the in-plane edge normal should
                    // point opposite to the surface normal.
                    bool bkwds = true;
                    if((tn.Cross(b.Minus(a))).Dot(sn) < 0) bkwds = !bkwds;
                    if(type == SShell::AS_DIFFERENCE && !opA) bkwds = !bkwds;
                    if(bkwds) {
                        inter.AddEdge(tb, ta, sc->h.v, 1);
                    } else {
                        inter.AddEdge(ta, tb, sc->h.v, 0);
                    }
                }
            }
        }
    }

    // Record all the points where more than two edges join, which I will call
    // the choosing points. If two edges join at a non-choosing point, then
    // they must either both be kept or both be discarded (since that would
    // otherwise create an open contour).
    SPointList choosing = {};
    SEdge *se;
    for(se = orig.l.First(); se; se = orig.l.NextAfter(se)) {
        choosing.IncrementTagFor(se->a);
        choosing.IncrementTagFor(se->b);
//.........这里部分代码省略.........

//.........这里部分代码省略.........
        }

        SInter *si;
        for(si = inters.First(); si; si = inters.NextAfter(si)) {
            Vector p = (si->p).Minus(axis.ScaledBy((si->p).Dot(axis)));
            double ub, vb;
            b->ClosestPointTo(p, &ub, &vb, /*mustConverge=*/true);
            SSurface plane;
            plane = SSurface::FromPlane(p, axis.Normal(0), axis.Normal(1));

            b->PointOnSurfaces(this, &plane, &ub, &vb);

            p = b->PointAt(ub, vb);

            SBezier bezier;
            bezier = SBezier::From(p.Plus(axis0), p.Plus(axis1));
            AddExactIntersectionCurve(&bezier, b, agnstA, agnstB, into);
        }

        inters.Clear();
        lv.Clear();
    } else {
        // Try intersecting the surfaces numerically, by a marching algorithm.
        // First, we find all the intersections between a surface and the
        // boundary of the other surface.
        SPointList spl = {};
        int a;
        for(a = 0; a < 2; a++) {
            SShell   *shA  = (a == 0) ? agnstA : agnstB;
            SSurface *srfA = (a == 0) ? this : b,
                     *srfB = (a == 0) ? b : this;

            SEdgeList el = {};
            srfA->MakeEdgesInto(shA, &el, MakeAs::XYZ, NULL);

            SEdge *se;
            for(se = el.l.First(); se; se = el.l.NextAfter(se)) {
                List<SInter> lsi = {};

                srfB->AllPointsIntersecting(se->a, se->b, &lsi,
                    /*asSegment=*/true, /*trimmed=*/true, /*inclTangent=*/false);
                if(lsi.n == 0) continue;

                // Find the other surface that this curve trims.
                hSCurve hsc = { (uint32_t)se->auxA };
                SCurve *sc = shA->curve.FindById(hsc);
                hSSurface hother = (sc->surfA.v == srfA->h.v) ?
                                                    sc->surfB : sc->surfA;
                SSurface *other = shA->surface.FindById(hother);

                SInter *si;
                for(si = lsi.First(); si; si = lsi.NextAfter(si)) {
                    Vector p = si->p;
                    double u, v;
                    srfB->ClosestPointTo(p, &u, &v);
                    srfB->PointOnSurfaces(srfA, other, &u, &v);
                    p = srfB->PointAt(u, v);
                    if(!spl.ContainsPoint(p)) {
                        SPoint sp;
                        sp.p = p;
                        // We also need the edge normal, so that we know in
                        // which direction to march.
                        srfA->ClosestPointTo(p, &u, &v);
                        Vector n = srfA->NormalAt(u, v);
                        sp.auxv = n.Cross((se->b).Minus(se->a));
                        sp.auxv = (sp.auxv).WithMagnitude(1);