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GCS: Improved point symmetry constraint

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=======================================

The original implementation won't work when the point is already on the line. See:
https://forum.freecadweb.org/viewtopic.php?f=3&t=29115#p237397

The new implementation works on the projections of the vectors linking the two first points with the symmetry point on the vector linking the two first points.

This assures that there is no stability problem when the point is already on the symmetry axis.
This commit is contained in:
Abdullah Tahiri
2018-06-08 17:05:40 +02:00
committed by wmayer
parent a6fa514665
commit f8d90fc6db
2 changed files with 34 additions and 25 deletions
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57
src/Mod/Sketcher/App/planegcs/Constraints.cpp
View File

@@ -527,37 +527,44 @@ void ConstraintPointOnPerpBisector::rescale(double coef)
scale = coef;
}
void ConstraintPointOnPerpBisector::errorgrad(double *err, double *grad, double *param)
{
DeriVector2 p0(Point(p0x(),p0y()), param);
DeriVector2 p1(Point(p1x(),p1y()), param);
DeriVector2 p2(Point(p2x(),p2y()), param);
DeriVector2 d1 = p0.subtr(p1);
DeriVector2 d2 = p0.subtr(p2);
DeriVector2 D = p2.subtr(p1).getNormalized();
double projd1, dprojd1;
projd1 = d1.scalarProd(D, &dprojd1);
double projd2, dprojd2;
projd2 = d2.scalarProd(D, &dprojd2);
if (err)
*err = projd1+projd2;
if (grad)
*grad = dprojd1+dprojd2;
}
double ConstraintPointOnPerpBisector::error()
{
double dx1 = *p1x() - *p0x();
double dy1 = *p1y() - *p0y();
double dx2 = *p2x() - *p0x();
double dy2 = *p2y() - *p0y();
return scale * (sqrt(dx1*dx1+dy1*dy1) - sqrt(dx2*dx2+dy2*dy2));
double err;
errorgrad(&err,0,0);
return scale * err;
}
double ConstraintPointOnPerpBisector::grad(double *param)
{
double deriv=0.;
if (param == p0x() || param == p0y() ||
param == p1x() || param == p1y()) {
double dx1 = *p1x() - *p0x();
double dy1 = *p1y() - *p0y();
if (param == p0x()) deriv -= dx1/sqrt(dx1*dx1+dy1*dy1);
if (param == p0y()) deriv -= dy1/sqrt(dx1*dx1+dy1*dy1);
if (param == p1x()) deriv += dx1/sqrt(dx1*dx1+dy1*dy1);
if (param == p1y()) deriv += dy1/sqrt(dx1*dx1+dy1*dy1);
}
if (param == p0x() || param == p0y() ||
param == p2x() || param == p2y()) {
double dx2 = *p2x() - *p0x();
double dy2 = *p2y() - *p0y();
if (param == p0x()) deriv += dx2/sqrt(dx2*dx2+dy2*dy2);
if (param == p0y()) deriv += dy2/sqrt(dx2*dx2+dy2*dy2);
if (param == p2x()) deriv -= dx2/sqrt(dx2*dx2+dy2*dy2);
if (param == p2y()) deriv -= dy2/sqrt(dx2*dx2+dy2*dy2);
}
return scale * deriv;
//first of all, check that we need to compute anything.
if ( findParamInPvec(param) == -1 ) return 0.0;
double deriv;
errorgrad(0, &deriv, param);
return deriv*scale;
}
// Parallel

2
src/Mod/Sketcher/App/planegcs/Constraints.h
View File

@@ -255,6 +255,7 @@ namespace GCS
inline double* p1y() { return pvec[3]; }
inline double* p2x() { return pvec[4]; }
inline double* p2y() { return pvec[5]; }
void errorgrad(double *err, double *grad, double *param);
public:
ConstraintPointOnPerpBisector(Point &p, Line &l);
ConstraintPointOnPerpBisector(Point &p, Point &lp1, Point &lp2);
@@ -263,6 +264,7 @@ namespace GCS
#endif
virtual ConstraintType getTypeId();
virtual void rescale(double coef=1.);
virtual double error();
virtual double grad(double *);
};