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Fixes IfcPolynomialCurve when used as IfcCurveSegment.ParentCurve in horizontal alignments

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This commit is contained in:
Richard Brice
2025-01-06 14:36:37 -08:00
parent 8313c05884
commit 933d845472
1 changed files with 13 additions and 10 deletions
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src/ifcgeom/mapping/IfcCurveSegment.cpp
+13 -10
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@@ -925,18 +925,22 @@ class curve_segment_evaluator {
// This functor is the derivative of y(x) => dy/dx = f'(x)
auto df = [lu=length_unit_,coeffY](double x) -> double {
auto begin = std::next(coeffY.begin());
auto iter = begin;
auto begin = coeffY.begin();
auto iter = std::next(begin);
auto end = coeffY.end();
double value = 0;
double lu_exp = 0.0;
// y = A0 + A1*x + A2*x^2 + A3*x^3
// y' = 0 + 1*A1*x^0 + 2*A2*x^1 + 3*A3*x^2
// The units of y are length. y' is unitless
// The units of x are length.
// A unit conversion of the coefficients is needed
// A1 = length^0
// A2 = length^-1
// A3 = Length^-2
for (; iter != end; iter++) {
auto exp = std::distance(begin, iter);
auto coeff = (*iter);
double a = (double)exp * coeff * pow(lu, lu_exp--);
double b = x ? pow(x, exp - 1) : 0; // when x and exp are zero? 0^-1 is infinite and the result is undefined
double v = a * b;
//double v = (double)exp * coeff * pow(lu, lu_exp--) * pow(x, exp - 1);
double v = (double)exp * coeff * pow(lu, 1-exp) * pow(x, exp - 1);
value += v;
}
return value;
@@ -986,14 +990,13 @@ class curve_segment_evaluator {
for (int i = 0; i < 2; i++) { // loop over X and Y
auto begin = coefficients[i]->cbegin();
auto end = coefficients[i]->cend();
double lu_exp = 1.0;
for (auto iter = begin; iter != end; iter++) {
auto exp = std::distance(begin, iter);
auto coeff = (*iter);
position[i] += coeff * pow(lu, lu_exp--) * pow(x, exp);
position[i] += coeff * pow(lu, 1-exp) * pow(x, exp);
if (iter != begin) {
slope[i] += coeff * pow(lu, lu_exp) * exp * pow(x, exp - 1);
slope[i] += exp * coeff * pow(lu, 1-exp) * pow(x, exp - 1);
}
}
}