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I am trying to draw circles from same y coordinate. and creating arrays for xPos. I put the speed and xPos random, how to make sure they are not overlapping and the one behind it match the speed to the front one so it wouldn't overtake?

I have retried the code, but it still overlapping for some reason that I couldn't find out? OK now I initialise the k with i+1, so whichever behind it. and I ran flow chart as well, the logic looks alright, still not doing what it should being doing.enter image description here

int Num=10;
float dia=50;
float[] xPos= new float[Num];
float[] xSpeed=new float[Num];
void setup() {
  size(300, 300);
  for (int i= 0; i<xPos.length; i++) {
    xPos[i]=random(-dia*Num);
    xSpeed[i]=3;
    boolean overlapping=false;
    for(int k=;k<xPos.length;k++){
       float newPos=xPos[k];
      float dist=(newPos-xPos[i]);
      if(dist<dia+50){
        overlapping=true;
        break;
      }
    }   
    if(!overlapping){
     draw();
    }
    }
  }
  

void draw() {
  background(255);
  drawBall();
  moveBall();
  reset();
}
void drawBall() {
  for (int i= 0; i<xPos.length; i++) {
    circle(xPos[i], 50, 50);
  }
}
void moveBall() {
  for (int i= 0; i<xPos.length; i++) {
    xPos[i]+=xSpeed[i];
  }
}
void reset() {
  for (int i= 0; i<xPos.length; i++) {
    if (xPos[i]>width) {
      xPos[i]=0;
    }
  }
}

1 Answers1

0

  1. how to make sure they are not overlapping

For this, you could naively check if the new position has already been taken by another such as follows (I haven't run the code, so i probably has bugs, think of it more as a pseudocode):

boolean isItTaken(float[] xPos, float newPos) {
  for (int i= 0; i<xPos.length; i++) {
    if (abs(newPos - xPos[i]) < circleSize) return true;
  }

  return false;
}

for (int i= 0; i<xPos.length; i++) {
  float newPos = random(-50);
  while (isItTaken(xPos, newPos)) {
     newPos = random(-50);
  }
}

I'm sure there are better methods though. Also I think using ArrayList is better than using a simple array.

  1. and the one behind it match the speed to the front one so it wouldn't overtake?

You could set it as a constant number? If you want it to be random, but slower than the previous one, you could set the upper limit of the random function to be the speed of the previous one such as(again, probably buggy):

ArrayList<Float> xSpeed = new ArrayList<Float>;


for (int i= 0; i < Num; i++) {
  xSpeed.push(random(2, xSpeed.get(xSpeed.length - 1)));
}
cSharp
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  • Hi, I have edited the code from the hint, and it seems still overlapping. I break the loop if the newPos is too close the xPos[i], it shouldn't have any overlap then, why this still happening? –  May 19 '22 at 03:49
  • Your current (edited) code does the following: 1. loop through the array with index `i` and set a random position in each loop. 2. in each loop, check all other indices `k` of the array for the distance. This includes `i` and will always cause `overlapping` to be `true` and `break`. 3. Once `overlapping` is `true`, you just call `draw`, and a new value is not assigned. – cSharp May 19 '22 at 04:37
  • Read through your code carefully, line by line and see what it's doing, instead of what you want it to do. A program is very explicit in what it's doing. – cSharp May 19 '22 at 04:38
  • I checked the scope again and did flow chart, it looks like what I am expecting that if overlaps is true go back, if overlap is false, draw and i++ –  May 19 '22 at 06:33
  • Where does it go back? In your `for[k]` loop, in `if( dist < dia + 50 )`, you only `break` out of the loop and move on to the next `for[i]` loop. – cSharp May 19 '22 at 06:38