CODEWITHSUNDEEP
htmlhtml5-canvas
ktbffh
ktbffh

Reputation: 43

HTML 5 Canvas - key pair value

previous arc needs to disappear and only the recent one should show up.

Here is the code I have until now.

    context.fill();
    context.closePath();
  }

})(document);

function randomColor() {
  var color = [];
  for (var i = 0; i < 3; i++) {
    color.push(Math.floor(Math.random() * 256));
  }
  return 'rgb(' + color.join(',') + ')';
}

<canvas id="testCanvas" style="border:1px solid #000000;"></canvas>

Upvotes: 1

Views: 60

Answers (1)

Helder Sepulveda
Helder Sepulveda

Reputation: 17644

Here is how to do it:

  • We need to keep a list of all circles
  • Loop over the circle checking if the click overlap a previous one
  • We need to detect overlaps (collisions) between two circles, easy Pythagorean calculation

Here is a working sample:

(function(doc) {

  var canvas = doc.getElementById("testCanvas");
  var context = canvas.getContext("2d");
  var circles = []

  function drawCircle(circle) {
    context.beginPath();
    context.fillStyle = circle.color;
    context.arc(circle.x, circle.y, circle.rad, 0, 2 * Math.PI, true);
    context.fill();
    context.closePath();
  }

  function collision(circle1, circle2) {
    var dx = circle1.x - circle2.x
    var dy = circle1.y - circle2.y
    return Math.sqrt(dx * dx + dy * dy) < (circle1.rad + circle2.rad);
  }

  function drawCircles(data) {
    context.clearRect(0, 0, canvas.width, canvas.height);
    drawCircle(data)
    for (var i = circles.length - 1; i >= 0; i--) {
      if (collision(circles[i], data)) {
        circles.splice(i, 1);
      } else {
        drawCircle(circles[i])
      }
    }
    circles.push(data)
  }

  // click event handler
  canvas.onclick = function(e) {
    drawCircles({
      color: randomColor(),
      rad: 5 + Math.random() * 30,
      x: e.clientX - e.target.offsetLeft,
      y: e.clientY - e.target.offsetTop
    })
  }

})(document);

function randomColor() {
  var color = [];
  for (var i = 0; i < 3; i++) {
    color.push(Math.floor(Math.random() * 256));
  }
  return 'rgb(' + color.join(',') + ')';
}
<canvas id="testCanvas" style="border:1px solid #000000;"></canvas>

To make it interesting I made the new circle with a random radius...
If you want to make things even more interesting (and have the time for it) instead of making the overlapping circles disappear, make them move & shrink until they do not overlap.

Upvotes: 2

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