Good day,

Maybe anyone knows how can I create a line from the center of any particle (line lenght = particle radius) , which would show direction in which the particle would be moving? I tried working with Vec2D, but got stuck while trying to create an average vector.

Here is the complete script:

1. import toxi.physics2d.behaviors.*;
2. import toxi.physics2d.*;
3. import toxi.geom.*;
4. import toxi.math.*;
5. ArrayList <Particle> particles;
6. ArrayList <Attractor> attractors = new ArrayList <Attractor>();
7. //Attractor attractor2;
8. int gridDim = 10;//30
9. VerletPhysics2D physics;
10. void setup() {
11.   size(1000, 600);
12.   smooth();
13.   int w = width/gridDim;
14.   int h = height/gridDim;
15.   //INITIALIZE PHYSICS
16.   physics = new VerletPhysics2D();
17.   physics.setDrag(0.1); //JUDEJIMO LAISVUMAS
18.   //INITIALIZE PARTICLE CLASS
19.   particles = new ArrayList<Particle>(); // PO SITO DEDAMI DOUBLE FOR LOOP GRIDUI
20.   for (int y = 0; y<gridDim; y++) {
21.     for (int x = 0; x<gridDim; x++) {
22.       particles.add(new Particle(new Vec2D(  (x+0.5)*w, (y+0.5)*h  )));
23.     }
24.   }
25.   //INITIALIZE ATTRACTOR CLASS
26.   attractors.add( new Attractor(new Vec2D(200, 200)));
27.   attractors.add( new Attractor(new Vec2D(900, 500)));
28.  
29. }
30. void draw() {
31.   background(255);
32.   //UPDATE PHYSICS
33.   physics.update();
34.   //ATTRACTION
35.    for (Attractor a: attractors){
36.   a.display();
37.   for (Particle p: particles) {
38.     p.display();
39.   }
40.   a.lock();//JEI UNLOCK ATTRACTOR POINTAS JUDES KARTU
41. }
42. }
43. class Attractor extends VerletParticle2D {
44.   float r;
45.   Attractor(Vec2D loc) {
46.     super(loc);
47.     r = 24;
48.     physics.addParticle(this);
49.     physics.addBehavior(new AttractionBehavior(this,300, 0.1));
50.   }
51.   void display () {
52.     fill(100);
53.     ellipse (x, y, r*2, r*2);
54.   }
55. }
56. class Connection extends VerletSpring2D {
57.   Connection(Particle p1, Particle p2, float len, float strength) {
58.     super(p1, p2, len, strength);
59.   }
60.  
61.   void display(){
62.     stroke(0);
63.     line(a.x,a.y,b.x,b.y);   
64.   }
65. }
66. class Particle extends VerletParticle2D {
67.  
68.   float r;
69.   Particle(Vec2D loc) {
70.     super(loc);
71.     r=10;
72.     physics.addParticle(this);
73.     physics.addBehavior(new AttractionBehavior(this, r*4, -1));
74.   
75.   }
76.  
77.   void display(){
78.     fill(255);
79.     stroke(2);
80.     
81.    ellipse(x,y,r*2,r*2);
82.   }
83. }