particle Class Reference

A representation of a 2D particle. More...

#include <particle.h>

Collaboration diagram for particle:

List of all members.

Public Member Functions
	particle ()
	Stationary particle.
	particle (doublec p0, doublec p1, doublec v0, doublec v1, doublec r)
	Initialize a particle.
boolc	isIntersecting (particle const &p2) const
	Do the two particles intersect?
void	step (doublec t)
	Increment the particle in time.
void	acczero ()
	Set the acceleration to zero.
ostream &	print (ostream &os) const
void	collisionDynamics (particle &p2)
	Collision resolution.
Public Attributes
float	radius
	The particles radius.
float	pos [2]
	The particles position.
float	vel [2]
	The particles velocity.
float	acc [2]
	The particles acceleration.

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Detailed Description

A representation of a 2D particle.

Definition at line 13 of file particle.h.

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Constructor & Destructor Documentation

particle::particle

(

)

[inline]

Stationary particle.

Definition at line 27 of file particle.h.

References acc, pos, and vel.

    : radius(0.0) { pos[0]=pos[1]=vel[0]=vel[1]=acc[0]=acc[1]=0.0; }

particle::particle	(	doublec	p0,
		doublec	p1,
		doublec	v0,
		doublec	v1,
		doublec	r
	)			[inline]

Initialize a particle.

Definition at line 32 of file particle.h.

References pos, radius, and vel.

    { pos[0]=p0; pos[1]=p1, vel[0]=v0; vel[1]=v1; radius=r; }

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Member Function Documentation

void particle::acczero

(

)

[inline]

Set the acceleration to zero.

Definition at line 60 of file particle.h.

References acc.

    { acc[0]=acc[1]=0.0; }

void particle::collisionDynamics

(

particle &

p2

)

Collision resolution.

Definition at line 3 of file particle.cpp.

References pos, and vel.

Referenced by integration< D, F >::bruteforce().

{
  float n[2], t[2], n_mag, n_mag_sq;
  float vi_nt[2], vj_nt[2], tmp;

  /* Normal vector between centres. */
  n[0] = p2.pos[0] - pos[0];
  n[1] = p2.pos[1] - pos[1];
  
  /* Normalise normal vector. */
  n_mag_sq = n[0] * n[0] + n[1] * n[1];
  n_mag = sqrt(n_mag_sq);
  n[0] /= n_mag;
  n[1] /= n_mag;

  /* Tangent vector. */
  t[0] = -n[1];
  t[1] = n[0];

  /* 
   * Resolve particle velocities into components in the 
   * normal and tangential direction. 
   */
  vi_nt[0] = p2.vel[0] * n[0] + p2.vel[1] * n[1];
  vi_nt[1] = p2.vel[0] * t[0] + p2.vel[1] * t[1];
  vj_nt[0] = vel[0] * n[0] + vel[1] * n[1];
  vj_nt[1] = vel[0] * t[0] + vel[1] * t[1];

  /* Interchange particle velocities along normal direction. */
  tmp = vi_nt[0];
  vi_nt[0] = vj_nt[0];
  vj_nt[0] = tmp;

  /* Resolve back. */
  p2.vel[0] = vi_nt[0] * n[0] + vi_nt[1] * t[0];
  p2.vel[1] = vi_nt[0] * n[1] + vi_nt[1] * t[1];
  vel[0] = vj_nt[0] * n[0] + vj_nt[1] * t[0];
  vel[1] = vj_nt[0] * n[1] + vj_nt[1] * t[1];

}

boolc particle::isIntersecting

(

particle const &

p2

)

const [inline]

Do the two particles intersect?

Definition at line 42 of file particle.h.

References pos, r, and radius.

  {
    doublec dy(p2.pos[1]-pos[1]);
    doublec dx(p2.pos[0]-pos[0]);
    doublec r(radius+p2.radius);
    return dy*dy+dx*dx < r*r;
  }

ostream& particle::print

(

ostream &

os

)

const [inline]

Definition at line 63 of file particle.h.

References acc, pos, radius, and vel.

Referenced by operator<<().

  {
    os << pos[0] << " " << pos[1] << " ";
    os << vel[0] << " " << vel[1] << " ";
    os << acc[0] << " " << acc[1] << " ";
    os << radius;
    return os;
  }

void particle::step

(

doublec

t

)

[inline]

Increment the particle in time.

Definition at line 51 of file particle.h.

References acc, pos, and vel.

Referenced by integration< D, F >::bruteforce(), boxcollision::down(), boxcollision::left(), boxcollision::right(), integration< D, F >::uniformgridtest(), and boxcollision::up().

  {
    vel[0] += t*acc[0];
    vel[1] += t*acc[1];
    pos[0] += t*vel[0];
    pos[1] += t*vel[1];
  }

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Member Data Documentation

float particle::acc[2]

The particles acceleration.

Definition at line 24 of file particle.h.

Referenced by acczero(), integration< D, F >::LJcalc(), particle(), print(), and step().

float particle::pos[2]

The particles position.

Definition at line 20 of file particle.h.

Referenced by collisionDynamics(), boxcollision::down(), particledisp::draw(), particlev0spaced::eval(), d2toindex::index(), isIntersecting(), boxcollision::left(), integration< D, F >::LJcalc(), particle(), print(), particledistribution::randomposition(), boxcollision::right(), step(), and boxcollision::up().

float particle::radius

The particles radius.

Definition at line 18 of file particle.h.

Referenced by boxcollision::down(), particledisp::draw(), particlev0spaced::eval(), particlev0theta0::eval(), particlev0::eval(), particleranvd::eval(), isIntersecting(), boxcollision::left(), particle(), print(), particledistribution::randomposition(), boxcollision::right(), and boxcollision::up().

float particle::vel[2]

The particles velocity.

Definition at line 22 of file particle.h.

Referenced by collisionDynamics(), boxcollision::down(), integration< D, F >::draw(), particlev0spaced::eval(), particlev0theta0::eval(), particlev0::eval(), particleranvd::eval(), boxcollision::left(), particle(), print(), boxcollision::right(), step(), and boxcollision::up().

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The documentation for this class was generated from the following files:

• nbody/particle.h
• nbody/particle.cpp