mirror of
https://github.com/photonstorm/phaser
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35 lines
1.1 KiB
JavaScript
35 lines
1.1 KiB
JavaScript
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var Point = require('../point/Point');
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/**
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* Get a point on the curve using the `t` (time) value, which must be between 0 and 1.
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*
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* @param {number} [t=0] - The time value along the curve from which to extract a point. This is a value between 0 and 1, where 0 represents the start of the curve and 1 the end.
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* @param {Phaser.Point|Object} [point] - An optional Phaser.Point, or Object containing public `x` and `y` properties. If given the resulting values will be stored in the Objects `x` and `y` properties. If omitted a new Phaser.Point object is created.
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* @return {Phaser.Point} An Object with the x, y coordinate of the curve at the specified `t` value set in its `x` and `y` properties.
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*/
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var GetPoint = function (curve, t, out)
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{
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if (t === undefined) { t = 0; }
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if (out === undefined) { out = new Point(); }
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if (t < 0)
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{
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t = 0;
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}
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if (t > 1)
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{
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t = 1;
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}
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var t2 = t * t;
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var t3 = t * t2;
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out.x = t3 * curve._ax + t2 * curve._bx + t * curve._v1x + curve._p1x;
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out.y = t3 * curve._ay + t2 * curve._by + t * curve._v1y + curve._p1y;
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return out;
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};
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module.exports = GetPoint;
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