phaser/wip/hermite/GetPoint.js

/**
* Get a point on the curve using the `t` (time) value, which must be between 0 and 1.
*
* @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.
* @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.
* @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.
*/
var GetPoint = function (curve, t, out)
{
    if (t === undefined) { t = 0; }
    if (out === undefined) { out = { x: 0, y: 0 }; }

    if (t < 0)
    {
        t = 0;
    }

    if (t > 1)
    {
        t = 1;
    }

    var t2 = t * t;
    var t3 = t * t2;

    out.x = t3 * curve._ax + t2 * curve._bx + t * curve._v1x + curve._p1x;
    out.y = t3 * curve._ay + t2 * curve._by + t * curve._v1y + curve._p1y;

    return out;
};

module.exports = GetPoint;