72 lines
1.7 KiB
JavaScript
72 lines
1.7 KiB
JavaScript
var Curves = {};
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Curves.createLinearBuffer = function createLinearBuffer(length, rotation) {
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var curve = new Float32Array(length),
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i, x,
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scale = length - 1;
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for (i = 0; i < length; i++) {
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x = i / scale;
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if (rotation > 0) {
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curve[i] = x;
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}
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else {
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curve[i] = 1 - x;
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}
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}
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return curve;
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};
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Curves.createExponentialBuffer = function createExponentialBuffer(length, rotation) {
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var curve = new Float32Array(length),
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i, x,
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scale = length - 1,
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index;
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for (i = 0; i < length; i++) {
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x = i / scale;
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index = rotation > 0 ? i : length - 1 - i;
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curve[index] = Math.exp(2 * x - 1) / Math.exp(1);
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}
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return curve;
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};
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//creating a curve to simulate an S-curve with setValueCurveAtTime.
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Curves.createSCurveBuffer = function createSCurveBuffer(length, phase) {
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var curve = new Float32Array(length),
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i;
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for (i = 0; i < length; ++i) {
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curve[i] = (Math.sin((Math.PI * i / length) - phase)) /2 + 0.5;
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}
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return curve;
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};
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//creating a curve to simulate a logarithmic curve with setValueCurveAtTime.
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Curves.createLogarithmicBuffer = function createLogarithmicBuffer(length, base, rotation) {
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var curve = new Float32Array(length),
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index,
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key = ""+length+base+rotation,
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store = [],
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x = 0,
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i;
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if (store[key]) {
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return store[key];
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}
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for (i = 0; i < length; i++) {
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//index for the curve array.
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index = rotation > 0 ? i : length - 1 - i;
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x = i / length;
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curve[index] = Math.log(1 + base*x) / Math.log(1 + base);
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}
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store[key] = curve;
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return curve;
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};
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