AdaptiveRepulsionData.h

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/** 
* Declaration of AdaptiveRepulsionData.
* @file AdaptiveRepulsionData.h
* @author Ed Bachta
*/

#ifndef __ADAPTIVEREPULSIONDATA_H__
#define __ADAPTIVEREPULSIONDATA_H__

#include "Particles.h"
#include "ParticleAttribute.h"

/**
* AdaptiveRepulsionData contains the parameters r, dr, and D along with
* constants which are needed to implement the Witkin-Heckbert model of
* adaptive particle repulsion. It is normally used by the ParticleRepulsion
* and ParticleFate behaviors to that effect.
*/
class AdaptiveRepulsionData : public ParticleAttribute {

public:

        MAKE_PARTICLESTUFF_NAME();

        // System attributes
        double sigma_hat; ///< Desired repulsion radius.
        double sigma_max; ///< Maximum repulsion radius.
        double diameter;        ///< Surface diameter.
        
        double alpha;      ///< Repulsion amplitude.
        double Ehat;             ///< Desired energy.

        /** # of std. dev.'s away that we expect repulsion to be zero
         * Defaults to 3 standard deviations.
         */
        double sdmul;

        int qlen();
        void getq(double *q);
        void setq(double *q);
        void qname(char **qn);

        // Per particle attributes

        /// Repulsion radii.
        std::vector<double> r;
        
        /// Change in repulsion radii.
        std::vector<double> dr;
        
        /// Particle energies.
        std::vector<double> D;

        int qlenpp();
        void getqpp(double *q, int i);
        void setqpp(double *q, int i);
        void qnamepp(char **qn);

        AdaptiveRepulsionData(Particles* ps=NULL,std::string name = std::string("AdaptiveRepulsionData"));

        virtual void setParticleSystem(Particles *);
        
        void clear();

        /** 
        * Integrate data over one time step.
        * @param dt Change in time to apply.
        */
        void integrate(double dt);

        /// Callback for particle removal.
        virtual void particleRemoved(unsigned int i);
        
        /// Callback for particle addition.
        virtual void particleAdded(unsigned int i);

        char *qtip(int i) { switch(i) {
                case 0: /* sigma_hat */ return "Desired distance between particles.";
                case 1: /* sigma_max */ return "Maximum distance between particles.";
                case 2: /* diameter */  return "Estimate of the diameter of the surface.";
                case 3: /* alpha */             return "Amplitude of the repulsion force. Proportional to particle motion response time, "
                                                                        "but if too large may cause stiffness";
                case 4: /* Ehat */              return "Desired energy of the system. Too much energy leads to jittery particles. "
                                                                        "Too little causes the particle system to appear sluggish.";
                case 5: /* sdmul */             return "Repulsion force is a Gaussian. The sdmul parameter is the number of "
                                                                        "standard deviations away from a particle that its repulsion force is "
                                                                        "tapered to zero.";
                default: return "";
        }}

        char *tip() { return "The AdaptiveRepulsionData particle attribute collects data shared "
                                                 "by several behaviors that collectively keep particles spaced "
                                                 "evenly.";
        }
};

#endif

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