topical media & game development
mobile-graphic-enchant-dev-src-Easing.js / js
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Easing Equations v2.0
September 1, 2003
(c) 2003 Robert Penner, all rights reserved.
This work is subject to the terms in http://www.robertpenner.com/easing_terms_of_use.html.
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[lang:ja]
イージング関数ライブラリ
{gray enchant.Easing} 以下にある関数は全て t(現在の時刻), b(初期値), c(変化後の値), d(値の変化にかける時間) の引数を取り、指定した時刻に取る値を返す。
ActionScript で広く使われている Robert Penner による Easing Equations を JavaScript に移植した。
see: www.robertpenner.com/easing/
see: www.robertpenner.com/easing/penner_chapter7_tweening.pdf
[/lang]
[lang:en]
[/lang]
Easing function library, from "Easing Equations" by Robert Penner.
@type {Object}
@namespace
{gray enchant.Tween} クラスで用いるイージング関数のライブラリ名前空間.
enchant.Easing = {
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
LINEAR: function(t, b, c, d) {
return c * t / d + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
SWING: function(t, b, c, d) {
return c * (0.5 - Math.cos(((t / d) * Math.PI)) / 2) + b;
},
// quad
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
QUAD_EASEIN: function(t, b, c, d) {
return c * (t /= d) * t + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
QUAD_EASEOUT: function(t, b, c, d) {
return -c * (t /= d) * (t - 2) + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
QUAD_EASEINOUT: function(t, b, c, d) {
if ((t /= d / 2) < 1) {
return c / 2 * t * t + b;
}
return -c / 2 * ((--t) * (t - 2) - 1) + b;
},
// cubic
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
CUBIC_EASEIN: function(t, b, c, d) {
return c * (t /= d) * t * t + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
CUBIC_EASEOUT: function(t, b, c, d) {
return c * ((t = t / d - 1) * t * t + 1) + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
CUBIC_EASEINOUT: function(t, b, c, d) {
if ((t /= d / 2) < 1) {
return c / 2 * t * t * t + b;
}
return c / 2 * ((t -= 2) * t * t + 2) + b;
},
// quart
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
QUART_EASEIN: function(t, b, c, d) {
return c * (t /= d) * t * t * t + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
QUART_EASEOUT: function(t, b, c, d) {
return -c * ((t = t / d - 1) * t * t * t - 1) + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
QUART_EASEINOUT: function(t, b, c, d) {
if ((t /= d / 2) < 1) {
return c / 2 * t * t * t * t + b;
}
return -c / 2 * ((t -= 2) * t * t * t - 2) + b;
},
// quint
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
QUINT_EASEIN: function(t, b, c, d) {
return c * (t /= d) * t * t * t * t + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
QUINT_EASEOUT: function(t, b, c, d) {
return c * ((t = t / d - 1) * t * t * t * t + 1) + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
QUINT_EASEINOUT: function(t, b, c, d) {
if ((t /= d / 2) < 1) {
return c / 2 * t * t * t * t * t + b;
}
return c / 2 * ((t -= 2) * t * t * t * t + 2) + b;
},
//sin
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
SIN_EASEIN: function(t, b, c, d) {
return -c * Math.cos(t / d * (Math.PI / 2)) + c + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
SIN_EASEOUT: function(t, b, c, d) {
return c * Math.sin(t / d * (Math.PI / 2)) + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
SIN_EASEINOUT: function(t, b, c, d) {
return -c / 2 * (Math.cos(Math.PI * t / d) - 1) + b;
},
// circ
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
CIRC_EASEIN: function(t, b, c, d) {
return -c * (Math.sqrt(1 - (t /= d) * t) - 1) + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
CIRC_EASEOUT: function(t, b, c, d) {
return c * Math.sqrt(1 - (t = t / d - 1) * t) + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
CIRC_EASEINOUT: function(t, b, c, d) {
if ((t /= d / 2) < 1) {
return -c / 2 * (Math.sqrt(1 - t * t) - 1) + b;
}
return c / 2 * (Math.sqrt(1 - (t -= 2) * t) + 1) + b;
},
// elastic
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
ELASTIC_EASEIN: function(t, b, c, d, a, p) {
if (t === 0) {
return b;
}
if ((t /= d) === 1) {
return b + c;
}
if (!p) {
p = d * 0.3;
}
var s;
if (!a || a < Math.abs(c)) {
a = c;
s = p / 4;
} else {
s = p / (2 * Math.PI) * Math.asin(c / a);
}
return -(a * Math.pow(2, 10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p)) + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
ELASTIC_EASEOUT: function(t, b, c, d, a, p) {
if (t === 0) {
return b;
}
if ((t /= d) === 1) {
return b + c;
}
if (!p) {
p = d * 0.3;
}
var s;
if (!a || a < Math.abs(c)) {
a = c;
s = p / 4;
} else {
s = p / (2 * Math.PI) * Math.asin(c / a);
}
return (a * Math.pow(2, -10 * t) * Math.sin((t * d - s) * (2 * Math.PI) / p) + c + b);
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
ELASTIC_EASEINOUT: function(t, b, c, d, a, p) {
if (t === 0) {
return b;
}
if ((t /= d / 2) === 2) {
return b + c;
}
if (!p) {
p = d * (0.3 * 1.5);
}
var s;
if (!a || a < Math.abs(c)) {
a = c;
s = p / 4;
} else {
s = p / (2 * Math.PI) * Math.asin(c / a);
}
if (t < 1) {
return -0.5 * (a * Math.pow(2, 10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p)) + b;
}
return a * Math.pow(2, -10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p) * 0.5 + c + b;
},
// bounce
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
BOUNCE_EASEOUT: function(t, b, c, d) {
if ((t /= d) < (1 / 2.75)) {
return c * (7.5625 * t * t) + b;
} else if (t < (2 / 2.75)) {
return c * (7.5625 * (t -= (1.5 / 2.75)) * t + 0.75) + b;
} else if (t < (2.5 / 2.75)) {
return c * (7.5625 * (t -= (2.25 / 2.75)) * t + 0.9375) + b;
} else {
return c * (7.5625 * (t -= (2.625 / 2.75)) * t + 0.984375) + b;
}
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
BOUNCE_EASEIN: function(t, b, c, d) {
return c - enchant.Easing.BOUNCE_EASEOUT(d - t, 0, c, d) + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
BOUNCE_EASEINOUT: function(t, b, c, d) {
if (t < d / 2) {
return enchant.Easing.BOUNCE_EASEIN(t * 2, 0, c, d) * 0.5 + b;
} else {
return enchant.Easing.BOUNCE_EASEOUT(t * 2 - d, 0, c, d) * 0.5 + c * 0.5 + b;
}
},
// back
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
BACK_EASEIN: function(t, b, c, d, s) {
if (s === undefined) {
s = 1.70158;
}
return c * (t /= d) * t * ((s + 1) * t - s) + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
BACK_EASEOUT: function(t, b, c, d, s) {
if (s === undefined) {
s = 1.70158;
}
return c * ((t = t / d - 1) * t * ((s + 1) * t + s) + 1) + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
BACK_EASEINOUT: function(t, b, c, d, s) {
if (s === undefined) {
s = 1.70158;
}
if ((t /= d / 2) < 1) {
return c / 2 * (t * t * (((s *= (1.525)) + 1) * t - s)) + b;
}
return c / 2 * ((t -= 2) * t * (((s *= (1.525)) + 1) * t + s) + 2) + b;
},
// expo
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
EXPO_EASEIN: function(t, b, c, d) {
return (t === 0) ? b : c * Math.pow(2, 10 * (t / d - 1)) + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
EXPO_EASEOUT: function(t, b, c, d) {
return (t === d) ? b + c : c * (-Math.pow(2, -10 * t / d) + 1) + b;
},
parameter: t
parameter: b
parameter: c
parameter: d
returns: {Number}
EXPO_EASEINOUT: function(t, b, c, d) {
if (t === 0) {
return b;
}
if (t === d) {
return b + c;
}
if ((t /= d / 2) < 1) {
return c / 2 * Math.pow(2, 10 * (t - 1)) + b;
}
return c / 2 * (-Math.pow(2, -10 * --t) + 2) + b;
}
};
Easing Equations v2.0
(C) Æliens
04/09/2009
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