Interaction among objects in an array

Programming Questions

josem.93

Interaction among objects in an array

in Programming Questions • 2 months ago

The code consists on some moving points. I'd like to draw lines from point to point when the distance that separates them is less than a certain number, but i don't know how can i make the point coordinates interact among them. HELP!

Copy code

Dots [] dots = new Dots [20];
void setup(){
size(800,600);
smooth();
for(int i = 0; i < dots.length; i++){
dots[i] = new Dots();
}
}
void draw(){
background(255);
for(int i = 0; i < dots.length; i++){
dots[i].move();
dots[i].display();
if (dots[i].intersect(dots[i])){
dots[i].drawLines(dots[i]);
}
}
}
class Dots{
float x,y; // position
float xspeed,yspeed;
float d; //diameter
color c;
Dots(){
x = width/2;
y = height/2;
d = 5;
c = color (200);
xspeed = random(-5,5);
yspeed = random(-5,5);
}
void display(){
noStroke();
fill(c);
ellipse(x,y,d,d);
}
void move(){
x += xspeed;
y += yspeed;
if(x > width || x < 0){
xspeed *= -1;
}
if(y > height || y < 0){
yspeed *= -1;
}
}
void drawLines(Dots b){
stroke(c);
line(x,y,b.x,b.y);
}
boolean intersect(Dots b){
float distance = abs(dist (x,y,b.x,b.y));
if(distance < 30){
return true;
} else {
return false;
}
}
}

Replies(3)

GoToLoop

Re: Interaction among objects in an array

2 months ago

Each Dot has to check against every1 else whether they're near; so a line() can be drawn linking them together.
Your code above only redundantly check a Dot against itself!
So you need an extra inner loop for each iteration of the outer 1.

Here's an online example:
http://studio.processingtogether.com/sp/pad/export/ro.9Kzw4QVZGKeFZ/latest

Some posts dealing w/ it:
http://forum.processing.org/topic/gradual-movement-within-a-for-loop
http://forum.processing.org/topic/drawing-a-network-of-nodes-and-links

And below's your code fixed:

Copy code

/** 
 * Moving Dots (v2.25)
 * by Josem.93 (2013/Aug)
 * mod GoToLoop
 * 
 * http://forum.processing.org/topic/interaction-among-objects-in-an-array
 * http://forum.processing.org/topic/gradual-movement-within-a-for-loop
 * 
 * http://studio.processingtogether.com/sp/pad/export/ro.9Kzw4QVZGKeFZ/latest
 */

final static int NUM = 30, FPS = 60;
final static Dot[] dots = new Dot[NUM];

boolean isPaused;

void setup() {
  size(800, 600);
  frameRate(FPS);
  smooth();
  stroke(Dot.COLOUR);
  fill(Dot.COLOUR);

  for (int i = 0; i != NUM; dots[i++] = new Dot());
}

void draw() {
  background(-1);
  for (int i = 0; i != NUM; connectPoints(i++))   dots[i].script();
}

void mousePressed() {
  if (isPaused = !isPaused)   noLoop();
  else                        loop();
}

void keyTyped() {
  mousePressed();
}

final static void connectPoints(int i) {
  for (int z = i+1; z != NUM; z++)
    if ( dots[i].isNear(dots[z]) )   dots[i].drawLine(dots[z]);
}

class Dot {
  final static short DIM = 5, MIN_DIST = 30, MAX_SPD = 5;
  final static color COLOUR = 0100;

  float x, y;
  float spx = random(-MAX_SPD, MAX_SPD);
  float spy = random(-MAX_SPD, MAX_SPD);

  Dot() {
    x = width>>1;
    y = height>>1;
  }

  void script() {
    move();
    display();
  }

  void move() {
    if ((x += spx) > width  | x < 0)  spx *= -1;
    if ((y += spy) > height | y < 0)  spy *= -1;
  }

  void display() {
    ellipse(x, y, DIM, DIM);
  }

  boolean isNear(Dot other) {
    //return dist(x, y, other.x, other.y) < MIN_DIST;
    return sq(other.x - x) + sq(other.y - y) < MIN_DIST*MIN_DIST;
    //return abs(other.x - x) < MIN_DIST && abs(other.y - y) < MIN_DIST;
  }

  void drawLine(Dot other) {
    line(x, y, other.x, other.y);
  }
}

GoToLoop

Re: Interaction among objects in an array

2 months ago

And a more advanced version using Comparable interface and sort() method from Arrays class:

Copy code

/**
 * Vector Dot Lines (v3.57)
 * by GokPotter (2013/Feb)
 * modders v.k., Thomas.Diewald, GoToLoop
 *
 * works faster when compiled in P1.5.1!
 *
 * http://forum.processing.org/topic/gradual-movement-within-a-for-loop
 * http://forum.processing.org/topic/drawing-a-network-of-nodes-and-links
 * http://forum.processing.org/topic/interaction-among-objects-in-an-array
 *
 * http://studio.processingtogether.com/sp/pad/export/ro.9Kzw4QVZGKeFZ/latest
 */

import java.util.Arrays;

final static color BG = -1, FG = 0;
final static short DOT_DIST  = 50, DOT_OPAC = 60;
final static float DOT_SPEED = 3, FPS = 60, BOLD = 1;

final static short NUM_DOTS  = 5000;
final static Point[] points = new Point[NUM_DOTS];

final static String GFX = P2D;  // Use P2D or JAVA2D

static int dotConnects;

void setup() {
  size(1024, 800, GFX);
  frameRate(FPS);
  noSmooth();
  strokeWeight(BOLD);
  stroke(FG, DOT_OPAC);

  for ( int i = 0; i != NUM_DOTS; 
  points[i++] = new Point(random(.5, DOT_SPEED)) );
}

void draw() {
  background(BG);

  Arrays.sort(points);

  final float minDist = map(mouseX, 0, width, 1, DOT_DIST);
  dotConnects = 0;

  for (int i = 0; i != NUM_DOTS;) {
    final Point p = points[i++];

    p.update();
    p.drawPoint();

    nearestNeighbors(p, i, minDist);
  }

  frame.setTitle(" Nearest neighbor"
    + " | fps "         + nf(frameRate, 0, 2)
    + " | minDist "     + nf(minDist, 0, 2)
    + " | numPoints "   + NUM_DOTS
    + " | numConnects " + dotConnects);
}

static final void nearestNeighbors(Point p1, int i, float minDist) {
  final float minDistSq = minDist * minDist;
  final float x = p1.x, y = p1.y;

  for (int j = i; j != NUM_DOTS;) {
    final Point p2 = points[j++];

    final float dx = p2.x - x;
    if (dx > minDist)   return;

    final float dy = abs(p2.y - y);
    if (dy > minDist)   continue;

    if (dx*dx + dy*dy < minDistSq) {
      p1.drawLine(p2);
      dotConnects++;
    }
  }
}

final class Point extends PVector implements Comparable<Point> {
  final PVector dir = new PVector();
  final float spd;

  Point(float speed) {
    spd = speed;
    init();
  }

  void init() {
    final float a = random(TWO_PI);
    dir.set(spd*cos(a), spd*sin(a), 0);
    set(random(width), random(height), 0);
  }

  void update() {
    add(dir);
    if ( isOffScreen() )   init();
  }

  boolean isOffScreen() {
    return x < 0 | x > width | y < 0 | y > height;
  }

  void drawPoint() {
    point(x, y);
  }

  void drawLine(Point other) {
    line(x, y, other.x, other.y);
  }

  int compareTo(Point other) {
    return (int) Math.signum(x - other.x);
  }
}

josem.93

Re: Interaction among objects in an array

2 months ago

Fixed and working. Thanks for the extra information, it will keep me busy for some time

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