Rewriting a sketch using inheritance

Programming Questions

air_wizar..

Rewriting a sketch using inheritance

in Programming Questions • 7 months ago

Hi guys, I want to rewrite a sketch (a single particle system) by using inheritance. The problem is that I don't see any variables that repeat themselves. Any suggestions?

ParticleSystem ps;
void setup() {
size(800,200);
smooth();
ps = new ParticleSystem(new PVector(width/2,50));
}
void draw() {
background(255);
ps.addParticle();
ps.run();
}
// A simple Particle class
class Particle {
PVector location;
PVector velocity;
PVector acceleration;
float lifespan;
Particle(PVector l) {
acceleration = new PVector(0,0.05);
velocity = new PVector(random(-1,1),random(-2,0));
location = l.get();
lifespan = 255.0;
}
void run() {
update();
display();
}
// Method to update location
void update() {
velocity.add(acceleration);
location.add(velocity);
lifespan -= 2.0;
}
// Method to display
void display() {
stroke(0,lifespan);
strokeWeight(2);
fill(127,lifespan);
ellipse(location.x,location.y,12,12);
}
// Is the particle still useful?
boolean isDead() {
if (lifespan < 0.0) {
return true;
} else {
return false;
}
}
}
// particle emitter
class ParticleSystem {
ArrayList<Particle> particles;
PVector origin;//keeps track of the origin point (each particle begins at this point)
ParticleSystem(PVector location) {
origin = location.get();
particles = new ArrayList<Particle>();
}
void addParticle() {
particles.add(new Particle(origin));
}
void run() {
Iterator<Particle> it = particles.iterator();
while (it.hasNext()) {
Particle p = it.next();
p.run();
if (p.isDead()) {
it.remove();
}
}
}
}

Replies(3)

quarks

Re: Rewriting a sketch using inheritance

7 months ago

Inheritance is used to represent ' a kind of' relationship between classes. You have two classes Particle and ParticleSystem since both of these statements are clearly invalid.
      Particle is a kind of ParticleSytem
      ParticleSystem is a kind of Particle
then there is no inheritance involved.

What you do have is aggregation, which is a ' has' relationship between classes e.g.
      ParticleSystem has Particle(s)
but you have already implemented that.

The problem is that I don't see any variables that repeat themselves.

Inheritance is not just about avoiding duplicate variables - look for the is kind of relationship between you classes to see if you might want to implement inheritance.

HTH

air_wizar..

Re: Rewriting a sketch using inheritance

7 months ago

I still have no clue where to begin from and how to create a super class

PhiLho

Re: Rewriting a sketch using inheritance

7 months ago

class SpecialParticle extends Particle
{
// Put additional fields there
int m;

SpecialParticle(PVector v)
{
    super(b); // Call constructor of super class
    // Other specific inits
    m = 42;
}
// Put here new methods or overrides of methods of the super class
}