concat PVectors array

jozze

Having and array of (random) PVectors, I want to concatenate 2 more "PVector" elements with fixed values. The thing is that I can not make it work with "concat" method for resizing the array.. what am I doin´wrong? thx!

class Agent {

PVector a;

Agent(){
a=new PVector(random(width),random(height));
}


}
// blabla

Agent [] a= new Agent(50);
PVector [] total;

PVector fixed1;
PVector fixed2;

//"solution1"
total=a.concat(fixed1,fixed2);

//"solution2"
PVector [] fixedValues ={ fixed1, fixed2}
total=a.concat(fixedValues);

GoToLoop

concat() demands 2 arrays of the same compatible type:
https://Processing.org/reference/concat_.html

You may try out append() instead:
https://Processing.org/reference/append_.html

Or even better, go w/ ArrayList:
https://Processing.org/reference/ArrayList.html

jozze

Tried out with ArrayList() as well. The idea is to have a sketch with a "repelling core" and 2 ArrayLists of PVectors: 1 with random values and another one with fixed values. Got a Null pointer exception in line 114:(??) :-w

int elements=50; 
PVector centro;
ArrayList <Agent> a = new ArrayList <Agent>();
Repeler rep;
ArrayList <FixedPoint> fp = new ArrayList <FixedPoint>();
Agent ag;

void setup() {//______________________________________________________________
  size(1400, 800);

  frameRate(30);
  smooth();

  centro= new PVector(width/2, height/2);
  rep = new Repeler(centro);

  for (int i=0; i<elements; i++) {
    a.add(new Agent());
    a.add(new FixedPoint());
  }
}

void draw() {//_______________________________________________________________
  background(100);

  for (int i=0; i<a.size(); i++) {
    ag= a.get(i); 

    PVector repulse = rep.attract(ag);
    ag.update(repulse);
    ag.run();
  }

  rep.display();
}


class Agent {//_______________________________________________________________
  PVector loc,vel,acc;

  Agent( ) {

    vel= new PVector (0,0);
    acc= new PVector (random (-.01, .01), random (-.01, .01));
  }

  void run() {
    move();
    display();
    limits();
  }

 void update(PVector force){  
   vel.add(force);
  }

  void move() {
    vel.add(acc);
    loc.add(vel);
    acc.mult(0);
  }

  void limits() {
    if (loc.x > width-100|| loc.x < 100 ) {
      vel.x = -vel.x ;
    } else if (loc.y > height-100 || loc.y < 100) {
      vel.y = -vel.y;
    }
  }

   void display() {
    noStroke();
    fill(0, 255, 0);
    ellipse(loc.x, loc.y, 5, 5);
  }
}


class FixedPoint extends Agent{//____________________________________________

  PVector loc1, loc2, loc3, loc4;


  FixedPoint( ) {

    loc1= new PVector(100, 100);
    loc2= new PVector(100, 700);
    loc3= new PVector(1300, 100);
    loc4= new PVector(1300, 700);
  }

  void run() {
    display();
  }

  void display() {
    fill(0, 0, 255);
    ellipse(loc1.x, loc1.y, 5, 5); 
    ellipse(loc2.x, loc2.y, 5, 5); 
    ellipse(loc3.x, loc3.y, 5, 5); 
    ellipse(loc4.x, loc4.y, 5, 5);
  }
}


class Repeler {//_____________________________________________________________
  PVector rep;

  Repeler(PVector _rep) {
    rep= _rep;
  }

  PVector attract(Agent ag) {
    PVector force= PVector.sub(rep, ag.loc);
    float dist=force.mag();

    dist=constrain(dist, 1., 2.);

    force.normalize();
    force.mult(-1); 
    return force;
  }


  void display() {
    noStroke();
    fill(255, 0, 0);
    ellipse(rep.x, rep.y, 50, 50);
  }
}

Lord_of_the_Galaxy

You should have initialized loc on line 42.
Was it a typing error?

jozze

thx for ur tip Lord_of_the_galaxy unforgivable mistake from my side :-??

Lord_of_the_Galaxy

OK, good.