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85 lines
2.6 KiB
C++
85 lines
2.6 KiB
C++
// $Id$
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//
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// Copyright (C) 2004-2006 Rational Discovery LLC
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//
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// @@ All Rights Reserved @@
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// This file is part of the RDKit.
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// The contents are covered by the terms of the BSD license
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// which is included in the file license.txt, found at the root
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// of the RDKit source tree.
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//
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#include "DistanceConstraint.h"
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#include <math.h>
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#include <ForceField/ForceField.h>
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#include <RDGeneral/Invariant.h>
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namespace ForceFields {
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namespace UFF {
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DistanceConstraintContrib::DistanceConstraintContrib(ForceField *owner,
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unsigned int idx1,unsigned int idx2,
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double minLen,double maxLen,
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double forceConst) {
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PRECONDITION(owner,"bad owner");
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RANGE_CHECK(0,idx1,owner->positions().size()-1);
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RANGE_CHECK(0,idx2,owner->positions().size()-1);
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PRECONDITION(maxLen>=minLen,"bad bounds");
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dp_forceField = owner;
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d_end1Idx = idx1;
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d_end2Idx = idx2;
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d_minLen = minLen;
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d_maxLen = maxLen;
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d_forceConstant = forceConst;
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}
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double DistanceConstraintContrib::getEnergy(double *pos) const {
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PRECONDITION(dp_forceField,"no owner");
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PRECONDITION(pos,"bad vector");
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//return 0.0;
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double dist=this->dp_forceField->distance(this->d_end1Idx,this->d_end2Idx,pos);
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double distTerm=0.0;
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if(dist<this->d_minLen){
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distTerm=this->d_minLen-dist;
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} else if(dist>this->d_maxLen) {
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distTerm=dist-this->d_maxLen;
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}
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double res = 0.5*this->d_forceConstant*distTerm*distTerm;
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//std::cerr << "DIST(" << this->d_end1Idx << ","<<this->d_end2Idx << "): " << this->d_maxLen << " " << dist << " E=" << res << std::endl;
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return res;
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}
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void DistanceConstraintContrib::getGrad(double *pos,double *grad) const {
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PRECONDITION(dp_forceField,"no owner");
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PRECONDITION(pos,"bad vector");
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PRECONDITION(grad,"bad vector");
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double dist=this->dp_forceField->distance(this->d_end1Idx,this->d_end2Idx,pos);
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double preFactor = 0.0;
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if(dist<this->d_minLen){
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preFactor=dist-this->d_minLen;
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} else if(dist>this->d_maxLen) {
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preFactor=dist-this->d_maxLen;
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} else {
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return;
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}
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preFactor *= this->d_forceConstant;
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double *end1Coords = &(pos[3*this->d_end1Idx]);
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double *end2Coords = &(pos[3*this->d_end2Idx]);
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for(int i=0;i<3;i++){
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double dGrad;
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if(dist>0.0){
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dGrad=preFactor * (end1Coords[i]-end2Coords[i])/dist;
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} else {
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// FIX: this likely isn't right
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dGrad=preFactor * (end1Coords[i]-end2Coords[i]);
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}
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grad[3*this->d_end1Idx+i] += dGrad;
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grad[3*this->d_end2Idx+i] -= dGrad;
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}
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}
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}
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}
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