common.h

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#pragma once
 
#include <ogdf/basic/Array.h>
#include <ogdf/basic/geometry.h>
 
#include <cmath>
 
namespace ogdf {
namespace spring_embedder {
 
template<typename NodeInfo>
class CommonForceModelBase {
public:
    CommonForceModelBase(const Array<NodeInfo>& vInfo, const Array<int>& adjLists,
            double idealEdgeLength)
        : m_vInfo(vInfo), m_adjLists(adjLists), m_idealEdgeLength(idealEdgeLength) { }
 
    double eps() const { return 0.01 * m_idealEdgeLength; }
 
protected:
    const Array<NodeInfo>& m_vInfo;
    const Array<int>& m_adjLists;
 
    double m_idealEdgeLength;
 
    double normByIdealEdgeLength(double norm) const {
        return (norm + eps()) / (m_idealEdgeLength + eps());
    }
 
    DPoint computeFruchtermanReingoldAttractiveForce(int j, int idealExponent) const {
        const NodeInfo& vj = m_vInfo[j];
 
        // attractive forces on j: F_attr(d) = -d^2 / iel
        DPoint force(0, 0);
        for (int i = vj.m_adjBegin; i != vj.m_adjStop; ++i) {
            int u = m_adjLists[i];
 
            DPoint dist = vj.m_pos - m_vInfo[u].m_pos;
            double d = dist.norm();
 
            dist *= d;
            force -= dist;
        }
 
        force /= std::pow(m_idealEdgeLength, idealExponent);
 
        return force;
    }
};
 
}
}