void killMomentum(void)
{
Vec3 P = momentum();
int n = numParticles();
Vec3 Pcorr = scale(P, -1/n);
forEveryParticleD(&addMomentum, (void*)&Pcorr);
}
void Particles::write(std::ofstream & out) const
{
int N = numParticles();
int size = sizeof(Vec2f) * N;
out.write(reinterpret_cast<const char*>(&N), sizeof(int));
out.write(reinterpret_cast<const char*>(&_pos[0]), size);
out.write(reinterpret_cast<const char*>(&_vel[0]), size);
}
bool physicsCheck(void)
{
Vec3 P = momentum();
double PPP = length(P) / numParticles();
//printf("%le\n",PPP);
if (PPP > 1e-20) {
fprintf(stderr, "\nMOMENTUM CONSERVATION VIOLATED! "
"Momentum per particle: |P| = %le\n", PPP);
return false;
}
return true;
}
void System<DataType,Integrator,Potential,Communicator>::updateForces() {
unsigned int numParts = numParticles() ;
for (auto i = forces.begin(); i != forces.end(); ++i) {
*i = 0 ;
}
// For each ij interaction calculate force. //
for (unsigned int i = 0 ; i < numParts*2 ; i+=2) {
for (unsigned int j = i+2 ; j < numParts*2 ; j+=2) {
// Get shortest connecting vector in periodic system. //
DataType x_comp = (positions[j] - positions[i]) ;
x_comp -= totCellLength*std::round(x_comp*totCellLengthInv) ;
DataType y_comp = positions[j+1] - positions[i+1] ;
y_comp -= totCellLength*std::round(y_comp*totCellLengthInv) ;
// Calculate the force for this vector using the distance. //
DataType distSqr = x_comp*x_comp + y_comp*y_comp ;
// Cutoff distance is when r = 2.5 sigma . //
if (distSqr < Potential::cutOffDistSqr) {
DataType forceMag = Potential::calcForce(distSqr) ;
DataType xForce = forceMag*x_comp ;
DataType yForce = forceMag*y_comp ;
forces[i] += xForce ;
forces[i+1] += yForce ;
forces[j] -= xForce ;
forces[j+1] -= yForce ;
}
}
}
// Consider the ghost particles. //
for (unsigned int i = 0 ; i < numParts*2 ; i+=2) {
for (unsigned int j = 0 ; j < boundaryGhostPositions.size() ; j+=2) {
// Get shortest connecting vector in periodic system. //
DataType x_comp = (boundaryGhostPositions[j] - positions[i]) ;
x_comp -= totCellLength*std::round(x_comp*totCellLengthInv) ;
DataType y_comp = boundaryGhostPositions[j+1] - positions[i+1] ;
y_comp -= totCellLength*std::round(y_comp*totCellLengthInv) ;
// Calculate the force for this vector using the distance. //
DataType distSqr = x_comp*x_comp + y_comp*y_comp ;
// Cutoff distance is when r = 2.5 sigma . //
if (distSqr < Potential::cutOffDistSqr) {
DataType forceMag = Potential::calcForce(distSqr) ;
DataType xForce = forceMag*x_comp ;
DataType yForce = forceMag*y_comp ;
forces[i] += xForce ;
forces[i+1] += yForce ;
}
}
}
} /* ----- end of member function updateForces ----- */
double getKineticTemperature(void)
{
return 2.0 / (3.0 * BOLTZMANN_CONSTANT)
* kineticEnergy() / numParticles();
}
osgParticle::Particle* ParticleSystem::createParticle(const osgParticle::Particle *ptemplate)
{
if (numParticles()-numDeadParticles() < mQuota)
return osgParticle::ParticleSystem::createParticle(ptemplate);
return NULL;
}
