initial commit

js/geo-slope.js

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+"use strict";
+
+var gs_base_slope = {
+    copyright:"stewart allen <stewart@neuron.com> -- all rights reserved"
+};
+
+(function() {
+
+    if (!self.base) self.base = {};
+    if (self.base.Slope) return;
+
+    /**
+     *
+     * @param p1
+     * @param p2
+     * @param dx
+     * @param dy
+     * @constructor
+     */
+    function Slope(p1, p2, dx, dy) {
+        this.dx = p1 && p2 ? p2.x - p1.x : dx;
+        this.dy = p1 && p2 ? p2.y - p1.y : dy;
+        this.angle = Math.atan2(this.dy, this.dx) * RAD2DEG;
+    }
+
+    var BASE = self.base,
+        CONF = BASE.config,
+        ABS = Math.abs,
+        SlP = Slope.prototype,
+        DEG2RAD = Math.PI / 180,
+        RAD2DEG = 180 / Math.PI;
+
+    BASE.Slope = Slope;
+    BASE.newSlope = newSlope;
+
+    BASE.newSlopeFromAngle = function(angle) {
+        return newSlope(0,0,
+            Math.cos(angle * DEG2RAD),
+            Math.sin(angle * DEG2RAD)
+        );
+    };
+
+    /** ******************************************************************
+     * Slope Prototype Functions
+     ******************************************************************* */
+
+    SlP.toString = function() {
+        return [this.dx, this.dy, this.angle].join(',');
+    };
+
+    /**
+     * @param {Slope} s
+     * @returns {boolean}
+     */
+    SlP.isSame = function(s) {
+        // if very close to vertical or horizontal, they're the same
+        if (ABS(this.dx) <= CONF.precision_merge && ABS(s.dx) <= CONF.precision_merge) return true;
+        if (ABS(this.dy) <= CONF.precision_merge && ABS(s.dy) <= CONF.precision_merge) return true;
+        // check angle within a range
+        var prec = Math.min(1/Math.sqrt(this.dx * this.dx + this.dy * this.dy), CONF.precision_slope_merge);
+        return angleWithinDelta(this.angle, s.angle, prec || CONF.precision_slope);
+    };
+
+    /**
+     * turn slope 90 degrees
+     *
+     * @returns {Slope}
+     */
+    SlP.normal = function() {
+        var t = this.dx;
+        this.dx = -this.dy;
+        this.dy = t;
+        this.angle = Math.atan2(this.dy, this.dx) * RAD2DEG;
+        return this;
+    };
+
+    SlP.toUnit = function() {
+        var max = Math.max(ABS(this.dx), ABS(this.dy));
+        this.dx = this.dx / max;
+        this.dy = this.dy / max;
+        return this;
+    };
+
+    SlP.factor = function(f) {
+        this.dx *= f;
+        this.dy *= f;
+        return this;
+    };
+
+    /**
+     * reverse (180 degree) slope
+     *
+     * @returns {Slope}
+     */
+    SlP.invert = function() {
+        this.dx = -this.dx;
+        this.dy = -this.dy;
+        this.angle = 360 - this.angle;//Math.atan2(this.dy, this.dx) * RAD2DEG;
+        return this;
+    };
+
+    /** ******************************************************************
+     * Connect to base and Helpers
+     ******************************************************************* */
+
+    /**
+     * returns true if the difference between a & b is less than v
+     *
+     * @param {number} a
+     * @param {number} b
+     * @param {number} v
+     * @returns {boolean}
+     */
+    function minDeltaABS(a,b,v) {
+        return ABS(a-b) < v;
+    }
+
+    function angleWithinDelta(a1, a2, delta) {
+        return (ABS(a1-a2) <= delta || 360-ABS(a1-a2) <= delta);
+    }
+
+    /**
+     *
+     * @param p1
+     * @param p2
+     * @param dx
+     * @param dy
+     * @returns {Slope}
+     */
+    function newSlope(p1, p2, dx, dy) {
+        return new Slope(p1, p2, dx, dy);
+    }
+
+})();