solvespace/srf/ratpoly.cpp
Jonathan Westhues 2f115ec950 A monster change to add support for filled paths. This requires us
to assemble Beziers into outer and inner loops, and find those
loops made up of entities with filled styles. The open paths are
maintained in a separate list, and we assemble as many closed paths
as possible even when open paths exist.

This changes many things. The coplanar check is now performed on
the Beziers, not the resulting polygon. The way that the polygon is
used to determine loop directions is also modified.

Also fix the mouse behavior when dragging a point: drop it when the
mouse is released, even if it is released outside the window, but
don't drop it if the pointer is dragged out of and then back into
our window.

Also special-case SSurface::ClosestPointTo() for planes, for speed.

[git-p4: depot-paths = "//depot/solvespace/": change = 2058]
2009-10-28 23:16:28 -08:00

589 lines
17 KiB
C++

//-----------------------------------------------------------------------------
// Math on rational polynomial surfaces and curves, typically in Bezier
// form. Evaluate, root-find (by Newton's methods), evaluate derivatives,
// and so on.
//-----------------------------------------------------------------------------
#include "../solvespace.h"
// Converge it to better than LENGTH_EPS; we want two points, each
// independently projected into uv and back, to end up equal with the
// LENGTH_EPS. Best case that requires LENGTH_EPS/2, but more is better
// and convergence should be fast by now.
#define RATPOLY_EPS (LENGTH_EPS/(1e2))
static double Bernstein(int k, int deg, double t)
{
if(k > deg || k < 0) return 0;
switch(deg) {
case 0:
return 1;
break;
case 1:
if(k == 0) {
return (1 - t);
} else if(k = 1) {
return t;
}
break;
case 2:
if(k == 0) {
return (1 - t)*(1 - t);
} else if(k == 1) {
return 2*(1 - t)*t;
} else if(k == 2) {
return t*t;
}
break;
case 3:
if(k == 0) {
return (1 - t)*(1 - t)*(1 - t);
} else if(k == 1) {
return 3*(1 - t)*(1 - t)*t;
} else if(k == 2) {
return 3*(1 - t)*t*t;
} else if(k == 3) {
return t*t*t;
}
break;
}
oops();
}
double BernsteinDerivative(int k, int deg, double t)
{
switch(deg) {
case 0:
return 0;
break;
case 1:
if(k == 0) {
return -1;
} else if(k = 1) {
return 1;
}
break;
case 2:
if(k == 0) {
return -2 + 2*t;
} else if(k == 1) {
return 2 - 4*t;
} else if(k == 2) {
return 2*t;
}
break;
case 3:
if(k == 0) {
return -3 + 6*t - 3*t*t;
} else if(k == 1) {
return 3 - 12*t + 9*t*t;
} else if(k == 2) {
return 6*t - 9*t*t;
} else if(k == 3) {
return 3*t*t;
}
break;
}
oops();
}
Vector SBezier::PointAt(double t) {
Vector pt = Vector::From(0, 0, 0);
double d = 0;
int i;
for(i = 0; i <= deg; i++) {
double B = Bernstein(i, deg, t);
pt = pt.Plus(ctrl[i].ScaledBy(B*weight[i]));
d += weight[i]*B;
}
pt = pt.ScaledBy(1.0/d);
return pt;
}
Vector SBezier::TangentAt(double t) {
Vector pt = Vector::From(0, 0, 0), pt_p = Vector::From(0, 0, 0);
double d = 0, d_p = 0;
int i;
for(i = 0; i <= deg; i++) {
double B = Bernstein(i, deg, t),
Bp = BernsteinDerivative(i, deg, t);
pt = pt.Plus(ctrl[i].ScaledBy(B*weight[i]));
d += weight[i]*B;
pt_p = pt_p.Plus(ctrl[i].ScaledBy(Bp*weight[i]));
d_p += weight[i]*Bp;
}
// quotient rule; f(t) = n(t)/d(t), so f' = (n'*d - n*d')/(d^2)
Vector ret;
ret = (pt_p.ScaledBy(d)).Minus(pt.ScaledBy(d_p));
ret = ret.ScaledBy(1.0/(d*d));
return ret;
}
void SBezier::ClosestPointTo(Vector p, double *t, bool converge) {
int i;
double minDist = VERY_POSITIVE;
*t = 0;
double res = (deg <= 2) ? 7.0 : 20.0;
for(i = 0; i < (int)res; i++) {
double tryt = (i/res);
Vector tryp = PointAt(tryt);
double d = (tryp.Minus(p)).Magnitude();
if(d < minDist) {
*t = tryt;
minDist = d;
}
}
Vector p0;
for(i = 0; i < (converge ? 15 : 5); i++) {
p0 = PointAt(*t);
if(p0.Equals(p, RATPOLY_EPS)) {
return;
}
Vector dp = TangentAt(*t);
Vector pc = p.ClosestPointOnLine(p0, dp);
*t += (pc.Minus(p0)).DivPivoting(dp);
}
if(converge) {
dbp("didn't converge (closest point on bezier curve)");
}
}
bool SBezier::PointOnThisAndCurve(SBezier *sbb, Vector *p) {
double ta, tb;
this->ClosestPointTo(*p, &ta, false);
sbb ->ClosestPointTo(*p, &tb, false);
int i;
for(i = 0; i < 20; i++) {
Vector pa = this->PointAt(ta),
pb = sbb ->PointAt(tb),
da = this->TangentAt(ta),
db = sbb ->TangentAt(tb);
if(pa.Equals(pb, RATPOLY_EPS)) {
*p = pa;
return true;
}
double tta, ttb;
Vector::ClosestPointBetweenLines(pa, da, pb, db, &tta, &ttb);
ta += tta;
tb += ttb;
}
return false;
}
void SBezier::SplitAt(double t, SBezier *bef, SBezier *aft) {
Vector4 ct[4];
int i;
for(i = 0; i <= deg; i++) {
ct[i] = Vector4::From(weight[i], ctrl[i]);
}
switch(deg) {
case 1: {
Vector4 cts = Vector4::Blend(ct[0], ct[1], t);
*bef = SBezier::From(ct[0], cts);
*aft = SBezier::From(cts, ct[1]);
break;
}
case 2: {
Vector4 ct01 = Vector4::Blend(ct[0], ct[1], t),
ct12 = Vector4::Blend(ct[1], ct[2], t),
cts = Vector4::Blend(ct01, ct12, t);
*bef = SBezier::From(ct[0], ct01, cts);
*aft = SBezier::From(cts, ct12, ct[2]);
break;
}
case 3: {
Vector4 ct01 = Vector4::Blend(ct[0], ct[1], t),
ct12 = Vector4::Blend(ct[1], ct[2], t),
ct23 = Vector4::Blend(ct[2], ct[3], t),
ct01_12 = Vector4::Blend(ct01, ct12, t),
ct12_23 = Vector4::Blend(ct12, ct23, t),
cts = Vector4::Blend(ct01_12, ct12_23, t);
*bef = SBezier::From(ct[0], ct01, ct01_12, cts);
*aft = SBezier::From(cts, ct12_23, ct23, ct[3]);
break;
}
default: oops();
}
}
void SBezier::MakePwlInto(SEdgeList *sel, double chordTol) {
List<Vector> lv;
ZERO(&lv);
MakePwlInto(&lv, chordTol);
int i;
for(i = 1; i < lv.n; i++) {
sel->AddEdge(lv.elem[i-1], lv.elem[i]);
}
lv.Clear();
}
void SBezier::MakePwlInto(List<SCurvePt> *l, double chordTol) {
List<Vector> lv;
ZERO(&lv);
MakePwlInto(&lv, chordTol);
int i;
for(i = 0; i < lv.n; i++) {
SCurvePt scpt;
scpt.tag = 0;
scpt.p = lv.elem[i];
scpt.vertex = (i == 0) || (i == (lv.n - 1));
l->Add(&scpt);
}
lv.Clear();
}
void SBezier::MakePwlInto(SContour *sc, double chordTol) {
List<Vector> lv;
ZERO(&lv);
MakePwlInto(&lv, chordTol);
int i;
for(i = 0; i < lv.n; i++) {
sc->AddPoint(lv.elem[i]);
}
lv.Clear();
}
void SBezier::MakePwlInto(List<Vector> *l, double chordTol) {
if(chordTol == 0) {
// Use the default chord tolerance.
chordTol = SS.ChordTolMm();
}
l->Add(&(ctrl[0]));
MakePwlWorker(l, 0.0, 1.0, chordTol);
}
void SBezier::MakePwlWorker(List<Vector> *l, double ta, double tb,
double chordTol)
{
Vector pa = PointAt(ta);
Vector pb = PointAt(tb);
// Can't test in the middle, or certain cubics would break.
double tm1 = (2*ta + tb) / 3;
double tm2 = (ta + 2*tb) / 3;
Vector pm1 = PointAt(tm1);
Vector pm2 = PointAt(tm2);
double d = max(pm1.DistanceToLine(pa, pb.Minus(pa)),
pm2.DistanceToLine(pa, pb.Minus(pa)));
double step = 1.0/SS.maxSegments;
if((tb - ta) < step || d < chordTol) {
// A previous call has already added the beginning of our interval.
l->Add(&pb);
} else {
double tm = (ta + tb) / 2;
MakePwlWorker(l, ta, tm, chordTol);
MakePwlWorker(l, tm, tb, chordTol);
}
}
Vector SSurface::PointAt(Point2d puv) {
return PointAt(puv.x, puv.y);
}
Vector SSurface::PointAt(double u, double v) {
Vector num = Vector::From(0, 0, 0);
double den = 0;
int i, j;
for(i = 0; i <= degm; i++) {
for(j = 0; j <= degn; j++) {
double Bi = Bernstein(i, degm, u),
Bj = Bernstein(j, degn, v);
num = num.Plus(ctrl[i][j].ScaledBy(Bi*Bj*weight[i][j]));
den += weight[i][j]*Bi*Bj;
}
}
num = num.ScaledBy(1.0/den);
return num;
}
void SSurface::TangentsAt(double u, double v, Vector *tu, Vector *tv) {
Vector num = Vector::From(0, 0, 0),
num_u = Vector::From(0, 0, 0),
num_v = Vector::From(0, 0, 0);
double den = 0,
den_u = 0,
den_v = 0;
int i, j;
for(i = 0; i <= degm; i++) {
for(j = 0; j <= degn; j++) {
double Bi = Bernstein(i, degm, u),
Bj = Bernstein(j, degn, v),
Bip = BernsteinDerivative(i, degm, u),
Bjp = BernsteinDerivative(j, degn, v);
num = num.Plus(ctrl[i][j].ScaledBy(Bi*Bj*weight[i][j]));
den += weight[i][j]*Bi*Bj;
num_u = num_u.Plus(ctrl[i][j].ScaledBy(Bip*Bj*weight[i][j]));
den_u += weight[i][j]*Bip*Bj;
num_v = num_v.Plus(ctrl[i][j].ScaledBy(Bi*Bjp*weight[i][j]));
den_v += weight[i][j]*Bi*Bjp;
}
}
// quotient rule; f(t) = n(t)/d(t), so f' = (n'*d - n*d')/(d^2)
*tu = ((num_u.ScaledBy(den)).Minus(num.ScaledBy(den_u)));
*tu = tu->ScaledBy(1.0/(den*den));
*tv = ((num_v.ScaledBy(den)).Minus(num.ScaledBy(den_v)));
*tv = tv->ScaledBy(1.0/(den*den));
}
Vector SSurface::NormalAt(Point2d puv) {
return NormalAt(puv.x, puv.y);
}
Vector SSurface::NormalAt(double u, double v) {
Vector tu, tv;
TangentsAt(u, v, &tu, &tv);
return tu.Cross(tv);
}
void SSurface::ClosestPointTo(Vector p, Point2d *puv, bool converge) {
ClosestPointTo(p, &(puv->x), &(puv->y), converge);
}
void SSurface::ClosestPointTo(Vector p, double *u, double *v, bool converge) {
// A few special cases first; when control points are coincident the
// derivative goes to zero at the conrol points, and would result in
// nonconvergence. We avoid that here, and also guarantee a consistent
// (u, v) (of the infinitely many possible in one parameter).
if(p.Equals(ctrl[0] [0] )) { *u = 0; *v = 0; return; }
if(p.Equals(ctrl[degm][0] )) { *u = 1; *v = 0; return; }
if(p.Equals(ctrl[degm][degn])) { *u = 1; *v = 1; return; }
if(p.Equals(ctrl[0] [degn])) { *u = 0; *v = 1; return; }
// And planes are trivial, so don't waste time iterating over those.
if(degm == 1 && degn == 1) {
Vector orig = ctrl[0][0],
bu = (ctrl[1][0]).Minus(orig),
bv = (ctrl[0][1]).Minus(orig);
if((ctrl[1][1]).Equals(orig.Plus(bu).Plus(bv))) {
Vector dp = p.Minus(orig);
*u = dp.Dot(bu) / bu.MagSquared();
*v = dp.Dot(bv) / bv.MagSquared();
return;
}
}
// Try whatever the previous guess was. This is likely to do something
// good if we're working our way along a curve or something else where
// we project successive points that are close to each other; something
// like a 20% speedup empirically.
if(converge) {
double ut = cached.x, vt = cached.y;
if(ClosestPointNewton(p, &ut, &vt, converge)) {
cached.x = *u = ut;
cached.y = *v = vt;
return;
}
}
// Search for a reasonable initial guess
int i, j;
double minDist = VERY_POSITIVE;
int res = (max(degm, degn) == 2) ? 7 : 20;
for(i = 0; i < res; i++) {
for(j = 0; j < res; j++) {
double tryu = (i + 0.5)/res, tryv = (j + 0.5)/res;
Vector tryp = PointAt(tryu, tryv);
double d = (tryp.Minus(p)).Magnitude();
if(d < minDist) {
*u = tryu;
*v = tryv;
minDist = d;
}
}
}
if(ClosestPointNewton(p, u, v, converge)) {
cached.x = *u;
cached.y = *v;
return;
}
// If we failed to converge, then at least don't return NaN.
if(isnan(*u) || isnan(*v)) {
*u = *v = 0;
}
}
bool SSurface::ClosestPointNewton(Vector p, double *u, double *v, bool converge)
{
// Initial guess is in u, v; refine by Newton iteration.
Vector p0;
for(int i = 0; i < (converge ? 25 : 5); i++) {
p0 = PointAt(*u, *v);
if(converge) {
if(p0.Equals(p, RATPOLY_EPS)) {
return true;
}
}
Vector tu, tv;
TangentsAt(*u, *v, &tu, &tv);
// Project the point into a plane through p0, with basis tu, tv; a
// second-order thing would converge faster but needs second
// derivatives.
Vector dp = p.Minus(p0);
double du = dp.Dot(tu), dv = dp.Dot(tv);
*u += du / (tu.MagSquared());
*v += dv / (tv.MagSquared());
}
if(converge) {
dbp("didn't converge");
dbp("have %.3f %.3f %.3f", CO(p0));
dbp("want %.3f %.3f %.3f", CO(p));
dbp("distance = %g", (p.Minus(p0)).Magnitude());
}
return false;
}
bool SSurface::PointIntersectingLine(Vector p0, Vector p1, double *u, double *v)
{
int i;
for(i = 0; i < 15; i++) {
Vector pi, p, tu, tv;
p = PointAt(*u, *v);
TangentsAt(*u, *v, &tu, &tv);
Vector n = (tu.Cross(tv)).WithMagnitude(1);
double d = p.Dot(n);
bool parallel;
pi = Vector::AtIntersectionOfPlaneAndLine(n, d, p0, p1, &parallel);
if(parallel) break;
// Check for convergence
if(pi.Equals(p, RATPOLY_EPS)) return true;
// Adjust our guess and iterate
Vector dp = pi.Minus(p);
double du = dp.Dot(tu), dv = dp.Dot(tv);
*u += du / (tu.MagSquared());
*v += dv / (tv.MagSquared());
}
// dbp("didn't converge (surface intersecting line)");
return false;
}
Vector SSurface::ClosestPointOnThisAndSurface(SSurface *srf2, Vector p) {
// This is untested.
int i, j;
Point2d puv[2];
SSurface *srf[2] = { this, srf2 };
for(j = 0; j < 2; j++) {
(srf[j])->ClosestPointTo(p, &(puv[j]), false);
}
for(i = 0; i < 10; i++) {
Vector tu[2], tv[2], cp[2], n[2];
double d[2];
for(j = 0; j < 2; j++) {
(srf[j])->TangentsAt(puv[j].x, puv[j].y, &(tu[j]), &(tv[j]));
cp[j] = (srf[j])->PointAt(puv[j]);
n[j] = ((tu[j]).Cross(tv[j])).WithMagnitude(1);
d[j] = (n[j]).Dot(cp[j]);
}
if((cp[0]).Equals(cp[1], RATPOLY_EPS)) break;
Vector p0 = Vector::AtIntersectionOfPlanes(n[0], d[0], n[1], d[1]),
dp = (n[0]).Cross(n[1]);
Vector pc = p.ClosestPointOnLine(p0, dp);
// Adjust our guess and iterate
for(j = 0; j < 2; j++) {
Vector dc = pc.Minus(cp[j]);
double du = dc.Dot(tu[j]), dv = dc.Dot(tv[j]);
puv[j].x += du / ((tu[j]).MagSquared());
puv[j].y += dv / ((tv[j]).MagSquared());
}
}
if(i >= 10) {
dbp("this and srf, didn't converge, d=%g",
(puv[0].Minus(puv[1])).Magnitude());
}
// If this converged, then the two points are actually equal.
return ((srf[0])->PointAt(puv[0])).Plus(
((srf[1])->PointAt(puv[1]))).ScaledBy(0.5);
}
void SSurface::PointOnSurfaces(SSurface *s1, SSurface *s2,
double *up, double *vp)
{
double u[3] = { *up, 0, 0 }, v[3] = { *vp, 0, 0 };
SSurface *srf[3] = { this, s1, s2 };
// Get initial guesses for (u, v) in the other surfaces
Vector p = PointAt(*u, *v);
(srf[1])->ClosestPointTo(p, &(u[1]), &(v[1]), false);
(srf[2])->ClosestPointTo(p, &(u[2]), &(v[2]), false);
int i, j;
for(i = 0; i < 20; i++) {
// Approximate each surface by a plane
Vector p[3], tu[3], tv[3], n[3];
double d[3];
for(j = 0; j < 3; j++) {
p[j] = (srf[j])->PointAt(u[j], v[j]);
(srf[j])->TangentsAt(u[j], v[j], &(tu[j]), &(tv[j]));
n[j] = ((tu[j]).Cross(tv[j])).WithMagnitude(1);
d[j] = (n[j]).Dot(p[j]);
}
// If a = b and b = c, then does a = c? No, it doesn't.
if((p[0]).Equals(p[1], RATPOLY_EPS) &&
(p[1]).Equals(p[2], RATPOLY_EPS) &&
(p[2]).Equals(p[0], RATPOLY_EPS))
{
*up = u[0];
*vp = v[0];
return;
}
bool parallel;
Vector pi = Vector::AtIntersectionOfPlanes(n[0], d[0],
n[1], d[1],
n[2], d[2], &parallel);
if(parallel) break;
for(j = 0; j < 3; j++) {
Vector dp = pi.Minus(p[j]);
double du = dp.Dot(tu[j]), dv = dp.Dot(tv[j]);
u[j] += du / (tu[j]).MagSquared();
v[j] += dv / (tv[j]).MagSquared();
}
}
dbp("didn't converge (three surfaces intersecting)");
}