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Index › Programming Questions & Help › Syntax Questions › dist() help, please

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dist() help, please (Read 939 times)

mayrp2001

dist() help, please
Jan 4^th, 2010, 12:02pm

Hi all, im having trouble working out how to use the dist() function. I want the ellipses to turn red when the line hits them. I know i should use the dist function but cant work out how to use it. any help would be greatly appreciated.
cheers

Code:

ArrayList balls;
int numBalls = 100;
int currentBall = 0;
int ballWidth = 25;
float y = 0.0;
boolean ball = false;
boolean start = false;
PFont font;



void setup(){
  size(500,550);
  smooth();
  balls = new ArrayList();
  font = loadFont("GillSans-48.vlw");
  textFont(font);
  
  
}
  


void draw(){
  background(0);
  stroke(247,15,15,200);
  strokeWeight(8);
  
  
  
  if(start == true){
  y = y + 2.0;
  line(y,0.0,y,500);
  if(y>=500){
    y=0;
  }
  }
 
 
 
  stroke(255);
  strokeWeight(4);
  line(0,100,500,100);
  line(0,200,500,200);
  line(0,300,500,300);
  line(0,400,500,400);
  fill(250,25,25);
  noStroke();
 
 
  rect(0,500,500,500);
    if((keyPressed == true) && (key == 's')){
    start = true;
  }
  
  
  fill(255);
  text("Press 's' to start",10,545);
  
  
  
  for(int i = balls.size()-1; i>=0;i--){
    Ball ball = (Ball) balls.get(i);
    ball.display();
  }
  }

  
 void mousePressed(){
   ball =true;
   balls.add(new Ball(mouseX, mouseY,ballWidth));
 }

BALL CLASS CODE:
Code:

class Ball{
  float x,y,w;
  

  Ball(float tempX, float tempY, float tempW){
    x = tempX;
    y = tempY;
    w = tempW;

  }
  
  void display(){
    fill(255);
    noStroke();
    ellipse(x,y,w,w);
  }
}

jeffg

Re: dist() help, please
Reply #1 - Jan 4^th, 2010, 1:32pm

Perhaps something like this:
Code:


  for(int i = balls.size()-1; i>=0;i--){
    Ball ball = (Ball) balls.get(i);
    if(ball.x-ballWidth/2 < y && ball.x+ballWidth/2 > y) {
	fill(255,0,0);
    } else {
	fill(255);
    }
    ball.display();
  }

Note that you need to remove the fill(255) from the ball.display() class code.

Also note that your use of the variable "y" for your line is really the x dimension (little confusing).

Cedric

Re: dist() help, please
Reply #2 - Jan 4^th, 2010, 1:48pm

you need to check the distance to y that actually should be x...
but you cant cause you create another x withing your class so i renamed it, and also made it flexible. that you can change the circlewidth...

Code:

ArrayList balls;
int numBalls = 100;
int currentBall = 0;
int ballWidth = 25;
float linex = 0.0;
boolean ball = false;
boolean start = false;
PFont font;



void setup(){
  size(500,550);
  smooth();
  balls = new ArrayList();
  font = createFont("GillSans-48.vlw",42);
  textFont(font);
  }
  


void draw(){
  background(0);
  stroke(247,15,15,200);
  strokeWeight(8);
  
  
  
  if(start == true){
  linex = linex + 2.0;
  line(linex,0.0,linex,500);
  if(linex>=500){
    linex=0;
  }
  }
 
 
 
  stroke(255);
  strokeWeight(4);
  line(0,100,500,100);
  line(0,200,500,200);
  line(0,300,500,300);
  line(0,400,500,400);
  fill(250,25,25);
  noStroke();
 
 
  rect(0,500,500,500);
    if((keyPressed == true) && (key == 's')){
    start = true;
  }
  
  
  fill(255);
  text("Press 's' to start",10,545);
  
  
  
  for(int i = balls.size()-1; i>=0;i--){
    Ball ball = (Ball) balls.get(i);
    ball.display();
  }
  }

  
 void mousePressed(){
   ball =true;
   balls.add(new Ball(mouseX, mouseY,ballWidth));
 }
 
 class Ball{
  float x,y,w;
  

  Ball(float tempX, float tempY, float tempW){
    x = tempX;
    y = tempY;
    w = tempW;

  }
  
  void display(){
    fill(255);
    noStroke();
    if(dist(x,0,linex,0)<=ballWidth/2)fill(255,0,0);
    if(dist(x,0,linex,0)>=ballWidth/2)fill(255);
    ellipse(x,y,w,w);
  }
}

twitter.com/CedricKiefer

mayrp2001 YaBB Newbies Offline Posts: 11	Re: dist() help, please Reply #3 - Jan 4^th, 2010, 3:05pm Thanks so much for all your help. Seriously first class help. Really appreciate it. p.s i know i stupidly called my variable y when it was referring to the x coordinate, kept meaning to change it but always had something else to fix. Cheers

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