Random function and constrain

Processing Coding Questions
1

Hello everybody, I’m working on a small personal exercise and I cannot undestrand how to avoid the born of random ball inside of the small square.
The idea is to fill only the white square and leave the pink-center square empty; I was thinking with map or constrain function but I never use it… Someone can help me?

CODE:

void setup () {
  size (1000, 1000);
  background (255);

  rectMode (CENTER);
  fill (255, 0, 0, 40);
  rect (width/2, height/2, 300, 300);
}

void draw() {
  float x = random (width);
  float y = random (height);
  fill(0,30);
  ellipse (x, y, 30, 30);
}
1 Like
2

You can either test a new ball if it’s not inside the rect and only then display it


void setup () {
  size (1000, 1000);
  background (255);

  rectMode (CENTER);
  fill (255, 0, 0, 40);
  rect (width/2, height/2, 300, 300);
}

void draw() {
  float x = random (width);
  float y = random (height);

  if ( ! (x>width/2-150 && x<width/2+150)) {  // **and the y-position of the ball???? How do you have to add this?   The ! means logical NOT** 
    fill(0, 30);
    ellipse (x, y, 30, 30);
  }
}

OR you just make the random values in a way that it’s automatically outside the inner rectangle, which is a bit harder, since the allowed area is AROUND the forbidden inner rectangle… (especially to distribute the points evenly)

Chrisir

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3

I don’t know how to manage the y position (height) in order to create the balls around the inner rectangle….

4

It’s the same as with x

if ( ! (x>width/2-150 && x<width/2+150 &&
y>height/2+150 && y height/2 + 150) ) {

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5

You may also be interested in this circle-rect collision detection demo:

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