Moved Hermite out for now.

Author: photonstorm

v3/src/paths/curves/hermite/FindT.js v3/merge/hermite/FindT.jsv3/src/paths/curves/hermite/FindT.js renamed to v3/merge/hermite/FindT.js

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+//  Created for Phaser 3
+//  Curve class based work done in three.js by [zz85](http://www.lab4games.net/zz85/blog)
+
+var Class = require('../../../utils/Class');
+var Curve = require('../Curve');
+var Vector2 = require('../../../math/Vector2');
+
+//  Phaser.Curves.Hermite
+
+/**
+* A data representation of a Hermite Curve (see http://en.wikipedia.org/wiki/Cubic_Hermite_spline)
+* 
+* A Hermite curve has a start and end point and tangent vectors for both of them.
+* The curve will always pass through the two control points and the shape of it is controlled
+* by the length and direction of the tangent vectors.  At the control points the curve will
+* be facing exactly in the vector direction.
+* 
+* As these curves change speed (speed = distance between points separated by an equal change in
+* 't' value - see Hermite.getPoint) this class attempts to reduce the variation by pre-calculating
+* the `accuracy` number of points on the curve. The straight-line distances to these points are stored
+* in the private 'points' array, and this information is used by Hermite.findT() to convert a pixel
+* distance along the curve into a 'time' value.
+* 
+* Higher `accuracy` values will result in more even movement, but require more memory for the points
+* list. 5 works, but 10 seems to be an ideal value for the length of curves found in most games on
+* a desktop screen. If you use very long curves (more than 400 pixels) you may need to increase
+* this value further.
+*
+* @param {number} p1x - The x coordinate of the start of the curve.
+* @param {number} p1y - The y coordinate of the start of the curve.
+* @param {number} p2x - The x coordinate of the end of the curve.
+* @param {number} p2y - The y coordinate of the end of the curve.
+* @param {number} v1x - The x component of the tangent vector for the start of the curve.
+* @param {number} v1y - The y component of the tangent vector for the start of the curve.
+* @param {number} v2x - The x component of the tangent vector for the end of the curve.
+* @param {number} v2y - The y component of the tangent vector for the end of the curve.
+* @param {number} [accuracy=10] The amount of points to pre-calculate on the curve.
+*/
+var HermiteCurve = new Class({
+
+    Extends: Curve,
+
+    initialize:
+
+    //  p0 = start point
+    //  p1 = end point
+    //  v0 = start tangent point
+    //  v1 = end tangent point
+    function HermiteCurve (p0, p1, v0, v1)
+    {
+        Curve.call(this);
+
+        if (Array.isArray(p0))
+        {
+            v1 = new Vector2(p0[6], p0[7]);
+            v0 = new Vector2(p0[4], p0[5]);
+            p1 = new Vector2(p0[2], p0[3]);
+            p0 = new Vector2(p0[0], p0[1]);
+        }
+
+        this.p0 = p0;
+        this.p1 = p1;
+        this.v0 = v0;
+        this.v1 = v1;
+    },
+
+    getStartPoint: function (out)
+    {
+        if (out === undefined) { out = new Vector2(); }
+
+        return out.copy(this.p0);
+    },
+
+    getResolution: function (divisions)
+    {
+        return divisions;
+    },
+
+    /**
+    * Performs the curve calculations.
+    *
+    * This is called automatically if you change any of the curves public properties, such as `Hermite.p1x` or `Hermite.v2y`.
+    *
+    * If you adjust any of the internal private values, then call this to update the points.
+    *
+    * @method Phaser.Hermite#recalculate
+    * @return {Phaser.Hermite} This object.
+    */
+    recalculate: function ()
+    {
+        this._ax = (2 * this._p1x - 2 * this._p2x + this._v1x + this._v2x);
+        this._ay = (2 * this._p1y - 2 * this._p2y + this._v1y + this._v2y);
+        this._bx = (-3 * this._p1x + 3 * this._p2x - 2 * this._v1x - this._v2x);
+        this._by = (-3 * this._p1y + 3 * this._p2y - 2 * this._v1y - this._v2y);
+
+        this.length = this.calculateEvenPoints();
+
+        return this;
+    },
+
+    getPoint: function (t, out)
+    {
+        if (out === undefined) { out = new Vector2(); }
+
+        var t2 = t * t;
+        var t3 = t * t2;
+
+        var ax = (2 * this.p0.x - 2 * this.p1.x + this.v0.x + this.v1.x);
+        var ay = (2 * this.p0.y - 2 * this.p1.y + this.v0.y + this.v1.y);
+        var bx = (-3 * this.p0.x + 3 * this.p1.x - 2 * this.v0.x - this.v1.x);
+        var by = (-3 * this.p0.y + 3 * this.p1.y - 2 * this.v0.y - this.v1.y);
+
+        out.x = t3 * ax + t2 * bx + t * this.v0.x + this.p0.x;
+        out.y = t3 * ay + t2 * by + t * this.v0.y + this.p0.y;
+
+        return out;
+    },
+
+    // Given u ( 0 .. 1 ), get a t to find p. This gives you points which are equidistant
+
+    getUtoTmapping: function (u, distance, divisions)
+    {
+        //  Find the _points which bracket the distance value
+        var ti = Math.floor(distance / this.length * divisions);
+
+        while (ti > 0 && this._points[ti] > distance)
+        {
+            ti--;
+        }
+
+        while (ti < divisions && this._points[ti] < distance)
+        {
+            ti++;
+        }
+
+        //  Linear interpolation to get a more accurate fix
+        var dt = this._points[ti] - this._points[ti - 1];
+        var d = distance - this._points[ti - 1];
+
+        return ((ti - 1) / divisions) + d / (dt * divisions);
+    },
+
+
+
+});
+
+module.exports = HermiteCurve;