f904c0fbee
piecwise linear segments. These are piecewise linear approximated for display, and currently for the mesh too, but that's the first step to replace the mesh with exact curved surfaces. [git-p4: depot-paths = "//depot/solvespace/": change = 1895]
130 lines
2.9 KiB
C++
130 lines
2.9 KiB
C++
#include "../solvespace.h"
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double Bernstein(int k, int deg, double t)
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{
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switch(deg) {
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case 1:
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if(k == 0) {
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return (1 - t);
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} else if(k = 1) {
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return t;
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}
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break;
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case 2:
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if(k == 0) {
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return (1 - t)*(1 - t);
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} else if(k == 1) {
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return 2*(1 - t)*t;
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} else if(k == 2) {
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return t*t;
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}
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break;
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case 3:
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if(k == 0) {
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return (1 - t)*(1 - t)*(1 - t);
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} else if(k == 1) {
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return 3*(1 - t)*(1 - t)*t;
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} else if(k == 2) {
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return 3*(1 - t)*t*t;
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} else if(k == 3) {
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return t*t*t;
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}
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break;
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}
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oops();
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}
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SPolyCurve SPolyCurve::From(Vector p0, Vector p1) {
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SPolyCurve ret;
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ZERO(&ret);
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ret.deg = 1;
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ret.weight[0] = ret.weight[1] = 1;
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ret.ctrl[0] = p0;
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ret.ctrl[1] = p1;
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return ret;
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}
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SPolyCurve SPolyCurve::From(Vector p0, Vector p1, Vector p2) {
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SPolyCurve ret;
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ZERO(&ret);
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ret.deg = 2;
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ret.weight[0] = ret.weight[1] = ret.weight[2] = 1;
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ret.ctrl[0] = p0;
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ret.ctrl[1] = p1;
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ret.ctrl[2] = p2;
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return ret;
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}
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SPolyCurve SPolyCurve::From(Vector p0, Vector p1, Vector p2, Vector p3) {
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SPolyCurve ret;
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ZERO(&ret);
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ret.deg = 3;
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ret.weight[0] = ret.weight[1] = ret.weight[2] = ret.weight[3] = 1;
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ret.ctrl[0] = p0;
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ret.ctrl[1] = p1;
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ret.ctrl[2] = p2;
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ret.ctrl[3] = p3;
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return ret;
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}
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Vector SPolyCurve::Start(void) {
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return ctrl[0];
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}
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Vector SPolyCurve::Finish(void) {
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return ctrl[deg];
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}
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Vector SPolyCurve::EvalAt(double t) {
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Vector pt = Vector::From(0, 0, 0);
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double d = 0;
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int i;
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for(i = 0; i <= deg; i++) {
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double B = Bernstein(i, deg, t);
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pt = pt.Plus(ctrl[i].ScaledBy(B*weight[i]));
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d += weight[i]*B;
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}
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pt = pt.ScaledBy(1.0/d);
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return pt;
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}
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void SPolyCurve::MakePwlInto(List<Vector> *l) {
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l->Add(&(ctrl[0]));
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MakePwlWorker(l, 0.0, 1.0);
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}
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void SPolyCurve::MakePwlWorker(List<Vector> *l, double ta, double tb) {
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Vector pa = EvalAt(ta);
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Vector pb = EvalAt(tb);
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// Can't test in the middle, or certain cubics would break.
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double tm1 = (2*ta + tb) / 3;
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double tm2 = (ta + 2*tb) / 3;
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Vector pm1 = EvalAt(tm1);
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Vector pm2 = EvalAt(tm2);
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double d = max(pm1.DistanceToLine(pa, pb.Minus(pa)),
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pm2.DistanceToLine(pa, pb.Minus(pa)));
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double tol = SS.chordTol/SS.GW.scale;
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double step = 1.0/SS.maxSegments;
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if((tb - ta) < step || d < tol) {
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// A previous call has already added the beginning of our interval.
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l->Add(&pb);
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} else {
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double tm = (ta + tb) / 2;
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MakePwlWorker(l, ta, tm);
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MakePwlWorker(l, tm, tb);
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}
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}
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void SPolyCurveList::Clear(void) {
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l.Clear();
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}
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