Circle Collision In Javascript

For school I need to make a program in JavaScript that says if circles had a collision. It doesn't need to be shown graphically. I gave it a try, but my code doesn't seem to work.

Solution 1:

Your check should be if (a > Math.sqrt((x*x) + (y*y)))http://cgp.wikidot.com/circle-to-circle-collision-detection

So the complete code is

functioncollision(p1x, p1y, r1, p2x, p2y, r2) {
  var a;
  var x;
  var y;

  a = r1 + r2;
  x = p1x - p2x;
  y = p1y - p2y;

  if (a > Math.sqrt((x * x) + (y * y))) {
    returntrue;
  } else {
    returnfalse;
  }
}
var collision = collision(5, 500, 10, 1000, 1500, 1500);
console.log(collision);

---

and for a less computational implementation (using ES7 syntax for the snippet) use

constcheckCollision = (p1x, p1y, r1, p2x, p2y, r2) => ((r1 + r2) ** 2 > (p1x - p2x) ** 2 + (p1y - p2y) ** 2)

var collision = checkCollision(5, 500, 10, 1000, 1500, 1500);
console.log(collision);

as Darek Rossman shows in his answer.

Solution 2:

In your if statement, try this instead:

if ( a * a > (x * x + y * y) ) {
    ...
} else {
    ...
}

Solution 3:

The length of a triangle having sides dx and dy (i.e. the distance between points (x1, y1) and (x2, y2) where dx = x2 - x1 and dy = y2 - y1) is equal to:

sqrt(dx^2 + dy^2)

So you probably want:

if(a > Math.sqrt(x*x + y*y)) {