Processing 1.0 - Processing Discourse - problem with collision detection

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problem with collision detection (Read 600 times)

Joe Rice

problem with collision detection
Oct 20^th, 2009, 5:54pm

so i am attempting to detect the collisions between a number of orbs on the screen. each orb can be selected with the mouse and dragged around the screen. eventually moving other orbs when they collide. i am currently using the equation of a circle to map the x,y coords for each orb on screen into two arrays(one for x values and one for y). currently it is detecting collisions when there are none happening and i can't figure out if i have simply miss written something or my syntax is off or if something far greater is causing problems. if you guys and girls out there can see anything that i can't please let me know. thanks

Code:

import ddf.minim.*;

int orbsize = 50;
int orbcount = 10;

AudioSample gong;
Minim minim;

Orb[] orbs = new Orb[orbcount];
float[] orbsx = new float[orbcount];
float[] orbsy = new float[orbcount];

boolean once = true;

int[] xtrail = new int[orbsize];
int[] ytrail = new int[orbsize];

float[][] detcolx = new float[orbcount][360];
float[][] detcoly = new float[orbcount][360];

void setup(){
  size(960,600);
  smooth();

  for(int i = 0; i < orbs.length; i++){
    orbsx[i] = random(25,935);
    orbsy[i] = random(25,575);
    orbs[i] = new Orb(orbsx[i],orbsy[i],orbsize);
  }

  for (int i = 0; i < xtrail.length; i ++ ) {
    xtrail[i] = 0; 
    ytrail[i] = 0;
  }



  minim = new Minim(this);
  gong = minim.loadSample("gong_d4.wav");


  //checkoverlap();
}
void draw(){

  background(0);
  //  for(int i = 0; i < detcolx.length; i++){
  //    detcolx[i] = new ArrayList();
  //    detcoly[i] = new ArrayList(); 
  //  }


  for(int i = 0; i < orbs.length; i++){
    orbs[i].display(); 
  }

  //checkoverlap();


  for(int i = 0; i < orbs.length; i++){

    if(mouseX > orbs[i].orbx-orbs[i].orbdia/2 && mouseX < orbs[i].orbx+orbs[i].orbdia/2 && mouseY > orbs[i].orby-orbs[i].orbdia/2 && mouseY < orbs[i].orby+orbs[i].orbdia/2 && mousePressed){
      orbs[i].orbx = mouseX;
      orbs[i].orby = mouseY;
      for(int n = 0; n < 360; n++){
        detcolx[i][n] = (orbs[i].orbx + orbs[i].orbdia*cos(n));
        detcoly[i][n] = (orbs[i].orby + orbs[i].orbdia*sin(n));
        println(n + ". " + detcolx[i][n] + ", " + detcoly[i][n]);
      }
      stroke(255);
      fill(0);

      for (int x = 0; x < xtrail.length-1; x ++ ) {
        xtrail[x] = xtrail[x+1];
        ytrail[x] = ytrail[x+1];
      }
      xtrail[xtrail.length-1] = mouseX;
      ytrail[ytrail.length-1] = mouseY;

      for (int t = 0; t < xtrail.length; t ++ ) {
        ellipse(xtrail[t],ytrail[t],t,t);
      }

      orbs[i].mouse = true;
      //      if(once == true){
      //        gong.trigger();
      //        once = false;
      //      }
      //player.rewind();
      detectCollision();
    }
    else if(!mousePressed){
      orbs[i].mouse = false;
      //minim.stop();
      //player.cue(0);
      //player = minim.loadFile("gong_d4.wav");
      //      if(once == true){
      //        player = minim.loadFile("gong_d4.wav");
      //        once = false;
      //      }
    }
  }

}

void checkoverlap(){
  int temp = 0;
  for(int i = 0; i < orbsx.length; i++){
    for(int x = 1; x < orbsx.length; x++){
      if((sqrt(sq(orbs[i].orbx-orbs[x].orbx)+sq(orbs[i].orby-orbs[x].orby))) < 50){

        orbs[i].orbx+=2;
        orbs[i].orby+=2;
        orbs[x].orbx-=2;
        orbs[x].orby-=2;
        //orbs[x].mouse = true;
        //player.play();
        //player.rewind();

      }
    }
  }
}

void mouseReleased(){
  //  gong.close();
  //  minim.stop();
  //  once = true;
}



void detectCollision(){
  for(int i = 0; i < detcolx.length; i++){
    for(int x = 1; x < detcolx.length; x ++){
      for(int n = 0; n < 360; n++){
        for(int t = 0; t < 360; t++){
          if(detcolx[i][n] == detcolx[x][t] && detcoly[i][n] == detcoly[i][t]){
            //println("Success!");
            //orbs[i].orbx+=25;
          }
        }
      }
    }
  }
}
class Orb{
  float orbx;
  float orby;
  float orbdia;
  boolean mouse;
  
  Orb(float x, float y, float dia){
    orbx = x;
    orby = y;
    orbdia = dia;
    mouse = false;

  }

  void display(){
    if(mouse == false){
      stroke(100,100,100);
    }
    else if(mouse == true){
      stroke(255);
    }
    strokeWeight(2);
    fill(0);
    ellipseMode(CENTER);
    ellipse(orbx, orby, 50,50);
    
  }
  
}

ben_hem

Re: problem with collision detection
Reply #1 - Oct 20^th, 2009, 7:29pm

Processing uses radians rather than degrees, 0 to TWO_PI. And if orbdia is diameter, that might be a source of problems -- it looks like you are essentially swinging an arm from the midpoint of the circle, and the arm is 50px while the circle is being drawn with radius 25px.

I am still not sure about storing a two-dimensional array for collision detection ... what about simply putting collision detection code, and appropriate response, into the orb class itself? You can also store the orbs' x and y values in the class.

By the way, if you respond to your original post, it'll pop to the top of the queue again -- no need for reposts.

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