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[Sketcher] [planegcs] Support point on NURBS

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This change adds support for rational B-splines. Non-uniform b-splines already
supported.
This commit is contained in:
Ajinkya Dahale
2022-10-11 20:00:00 +05:30
committed by abdullahtahiriyo
parent b3c4975b09
commit 233f976b63
2 changed files with 28 additions and 13 deletions
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40
src/Mod/Sketcher/App/planegcs/Constraints.cpp
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@@ -490,6 +490,8 @@ ConstraintPointOnBSpline::ConstraintPointOnBSpline(double* point, double* initpa
else
pvec.push_back(b.poles[(startpole + i) % b.poles.size()].y);
}
for (size_t i = 0; i < numpoints; ++i)
pvec.push_back(b.weights[(startpole + i) % b.weights.size()]);
factors.resize(numpoints);
if (b.flattenedknots.empty())
@@ -511,47 +513,59 @@ void ConstraintPointOnBSpline::rescale(double coef)
double ConstraintPointOnBSpline::error()
{
// We need to find factors over and over again because param can change.
// TODO: We don't need to find the factors here, just for grad.
// Calculate position with factors because we have the method.
double sum = 0;
double wsum = 0;
// TODO: maybe make it global so it doesn't have to be created every time
VEC_D d(numpoints);
// TODO: Also support rational b-splines
for (size_t i = 0; i < numpoints; ++i)
d[i] = *poleat(i);
sum += BSpline::splineValue(*theparam(), startpole + bsp.degree, bsp.degree, d, bsp.flattenedknots);
d[i] = *poleat(i) * *weightat(i);
sum = BSpline::splineValue(*theparam(), startpole + bsp.degree, bsp.degree, d, bsp.flattenedknots);
for (size_t i = 0; i < numpoints; ++i)
d[i] = *weightat(i);
wsum = BSpline::splineValue(*theparam(), startpole + bsp.degree, bsp.degree, d, bsp.flattenedknots);
// TODO: Change the poles as the point moves between pieces
return scale * (*thepoint() - sum);
return scale * (*thepoint() * wsum - sum);
}
double ConstraintPointOnBSpline::grad(double *gcsparam)
{
double deriv=0.;
if (gcsparam == thepoint()) {
// TODO: Change this for rational splines
deriv += 1.;
VEC_D d(numpoints);
for (size_t i = 0; i < numpoints; ++i)
d[i] = *weightat(i);
double wsum = BSpline::splineValue(*theparam(), startpole + bsp.degree, bsp.degree, d, bsp.flattenedknots);
deriv += wsum;
}
if (gcsparam == theparam()) {
// TODO: Implement derivative and return value
VEC_D d(numpoints - 1);
for (size_t i = 1; i < numpoints; ++i) {
d[i-1] =
(*poleat(i) - *poleat(i-1)) /
(*poleat(i) * *weightat(i) - *poleat(i-1) * *weightat(i-1)) /
(bsp.flattenedknots[startpole+i+bsp.degree] - bsp.flattenedknots[startpole+i]);
}
double slopevalue = BSpline::splineValue(*theparam(), startpole + bsp.degree, bsp.degree-1, d, bsp.flattenedknots);
deriv -= bsp.degree * slopevalue;
for (size_t i = 1; i < numpoints; ++i) {
d[i-1] =
(*weightat(i) - *weightat(i-1)) /
(bsp.flattenedknots[startpole+i+bsp.degree] - bsp.flattenedknots[startpole+i]);
}
double wslopevalue = BSpline::splineValue(*theparam(), startpole + bsp.degree, bsp.degree-1, d, bsp.flattenedknots);
deriv += (*thepoint() * wslopevalue - slopevalue) * bsp.degree;
}
for (size_t i = 0; i < numpoints; ++i) {
if (gcsparam == poleat(i)) {
factors[i] = bsp.getLinCombFactor(*theparam(), startpole + bsp.degree, startpole + i);
deriv += -factors[i];
deriv += -(*weightat(i) * factors[i]);
}
if (gcsparam == weightat(i)) {
factors[i] = bsp.getLinCombFactor(*theparam(), startpole + bsp.degree, startpole + i);
deriv += (*thepoint() - *poleat(i)) * factors[i];
}
}

1
src/Mod/Sketcher/App/planegcs/Constraints.h
View File

@@ -241,6 +241,7 @@ namespace GCS
// TODO: better name because param has a different meaning here?
inline double* theparam() { return pvec[1]; }
inline double* poleat(size_t i) { return pvec[2 + i]; }
inline double* weightat(size_t i) { return pvec[2 + numpoints + i]; }
public:
/// TODO: Explain how it's provided
/// coordidx = 0 if x, 1 if y