)
}
}
)
(
}
{
)
)
(
)
(
(
{
}
)
(
)
}
)
)
{
(
(
)
)
}
)
(
}

Raphaël Easing Equations How To

  1. const { pow, PI } = Math;
  2.  
  3. // mostly unedited code from Raphaël
  4. var ef = {
  5.   linear: function(n) {
  6.     return n;
  7.   },
  8.   '<': function(n) {
  9.     return pow(n, 1.7);
  10.   },
  11.   '>': function(n) {
  12.     return pow(n, 0.48);
  13.   },
  14.   '<>': function(n) {
  15.     var q = 0.48 - n / 1.04,
  16.       Q = Math.sqrt(0.1734 + q * q),
  17.       x = Q - q,
  18.       X = pow(abs(x), 1 / 3) * (x < 0 ? -1 : 1),
  19.       y = -Q - q,
  20.       Y = pow(abs(y), 1 / 3) * (y < 0 ? -1 : 1),
  21.       t = X + Y + 0.5;
  22.     return (1 - t) * 3 * t * t + t * t * t;
  23.   },
  24.   backIn: function(n) {
  25.     var s = 1.70158;
  26.     return n * n * ((s + 1) * n - s);
  27.   },
  28.   backOut: function(n) {
  29.     n = n - 1;
  30.     var s = 1.70158;
  31.     return n * n * ((s + 1) * n + s) + 1;
  32.   },
  33.   elastic: function(n) {
  34.     if (n == !!n) {
  35.       return n;
  36.     }
  37.     return pow(2, -10 * n) * Math.sin(((n - 0.075) * (2 * PI)) / 0.3) + 1;
  38.   },
  39.   bounce: function(n) {
  40.     var s = 7.5625,
  41.       p = 2.75,
  42.       l;
  43.     if (n < 1 / p) {
  44.       l = s * n * n;
  45.     } else {
  46.       if (n < 2 / p) {
  47.         n -= 1.5 / p;
  48.         l = s * n * n + 0.75;
  49.       } else {
  50.         if (n < 2.5 / p) {
  51.           n -= 2.25 / p;
  52.           l = s * n * n + 0.9375;
  53.         } else {
  54.           n -= 2.625 / p;
  55.           l = s * n * n + 0.984375;
  56.         }
  57.       }
  58.     }
  59.     return l;
  60.   }
  61. };
  62. ef.easeIn = ef['ease-in'] = ef['<'];
  63. ef.easeOut = ef['ease-out'] = ef['>'];
  64. ef.easeInOut = ef['ease-in-out'] = ef['<>'];
  65. ef['back-in'] = ef.backIn;
  66. ef['back-out'] = ef.backOut;
  67.  
  68. // create a dot
  69. function dot(x, y, radius, color) {
  70.   const el = document.createElement('div');
  71.   const size = `${radius * 2}px`;
  72.   Object.assign(el.style, {
  73.     position: 'absolute',
  74.     left: `${x}px`,
  75.     top: `${y}px`,
  76.     width: size,
  77.     height: size,
  78.     transform: `translate(${-radius}px, ${-radius}px)`,
  79.     borderRadius: '50%',
  80.     background: color
  81.   });
  82.   el.classList.add('dot');
  83.   document.body.appendChild(el);
  84.   return el;
  85. }
  86.  
  87. const elA = dot(0, 40, 30, 'red');
  88. const elB = dot(0, 110, 30, 'blue');
  89. const elC = dot(0, 160, 20, 'green');
  90.  
  91. // how to use the easing equations:
  92. let t = 0;
  93.  
  94. let start = Date.now();
  95. let time = 0;
  96. let duration = 2; // 2 seconds
  97. function loop() {
  98.   // frame based
  99.   elA.style.left = `${ef.elastic(t) * 50}%`;
  100.   t += 0.005;
  101.  
  102.   // time based
  103.   if (time <= duration) {
  104.     time = (Date.now() - start) / 1000;
  105.     const param = time / duration;
  106.     elB.style.left = `${ef.elastic(param) * 50}%`;
  107.  
  108.     // green bounce example
  109.     elC.style.left = `${ef.bounce(param) * 50}%`;
  110.   }
  111.  
  112.   requestAnimationFrame(loop);
  113. }
  114. loop();

I realized it might not be obvious how to use Raphaël’s easing equations. So I speed coded this example.

If you’d like to learn more about this kind of thing gsap is a great place to start… it is amazing… I highly recommend browsing the source.

snippet.zone ~ 2021-22 /// {s/z}