Method SplitAt

src/LNLib/Geometry/Volume/NurbsVolume.cpp:486–671

}

bool LNLib::NurbsVolume::SplitAt(const LN_NurbsVolume& volume, double parameter, VolumeDirection direction, LN_NurbsVolume& first, LN_NurbsVolume& second)
{
	int degreeU = volume.DegreeU;
	int degreeV = volume.DegreeV;
	int degreeW = volume.DegreeW;

	std::vector<double> kvU = volume.KnotVectorU;
	std::vector<double> kvV = volume.KnotVectorV;
	std::vector<double> kvW = volume.KnotVectorW;

	std::vector<std::vector<std::vector<LNLib::XYZW>>> controlPoints = volume.ControlPoints;

	LN_NurbsVolume insertVolume;
	int k, s, rr;

	if (direction == VolumeDirection::U)
	{
		if (LNLib::MathUtils::IsAlmostEqualTo(parameter, kvU[0]) ||
			LNLib::MathUtils::IsAlmostEqualTo(parameter, kvU[kvU.size() - 1]))
		{
			first = volume;
			second = volume;
			return true;
		}

		k = LNLib::Polynomials::GetKnotSpanIndex(degreeU, kvU, parameter);
		s = LNLib::Polynomials::GetKnotMultiplicity(kvU, parameter);
		rr = degreeU - s;

		if (rr > 0)
		{
			InsertKnot(volume, parameter, rr, direction, insertVolume);

			kvU = insertVolume.KnotVectorU;
			kvV = insertVolume.KnotVectorV;
			kvW = insertVolume.KnotVectorW;
			controlPoints = insertVolume.ControlPoints;

			k = LNLib::Polynomials::GetKnotSpanIndex(degreeU, kvU, parameter);
			s = LNLib::Polynomials::GetKnotMultiplicity(kvU, parameter);
		}

		std::vector<double> kU_L = kvU;
		kU_L.resize(k + 2);
		kU_L.back() = parameter;

		std::vector<double> kU_R;
		kU_R.push_back(parameter);
		kU_R.insert(kU_R.end(), kvU.begin() + (k - s + 1), kvU.end());

		std::vector<std::vector<std::vector<LNLib::XYZW>>> cp_L(controlPoints.begin(), controlPoints.begin() + (k - s + 1));
		std::vector<std::vector<std::vector<LNLib::XYZW>>> cp_R(controlPoints.begin() + (k - s), controlPoints.end());

		first.DegreeU = degreeU; first.DegreeV = degreeV; first.DegreeW = degreeW;
		first.KnotVectorU = kU_L; first.KnotVectorV = kvV; first.KnotVectorW = kvW;
		first.ControlPoints = cp_L;

		second.DegreeU = degreeU; second.DegreeV = degreeV; second.DegreeW = degreeW;