FTrig/FTrig.js at master · netcell/FTrig · GitHub

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/*
 * Fast Trigonometric with Javascript by netcell
 * REF: http://lab.polygonal.de/?p=205
 */

var abs = Math.abs;
(function() {
	var FTrig = (function() {
		/*
		 * Create a FTrig instance with accuracyLevel of
		 * - FTrig.LOW: faster and less accurate, or
		 * - FTrig.HIGH: slower and more accurate
		 * Exposes 2 functions: sin and cos
		 */
		var FTrig = function(accuracyLevel) {
			switch (accuracyLevel) {
				case FTrig.LOW:
					this.sin = this.sinLow;
					this.cos = this.cosLow;
				break;
				case FTrig.HIGH:
					this.sin = this.sinHigh;
					this.cos = this.cosHigh;
				break;
			}
		};

		FTrig.LOW  = 1;
		FTrig.HIGH = 2;

		FTrig.prototype = {
			sinHigh: function(x){
				var sin;
				if (x < -3.14159265) x += 6.28318531;
				else if (x >  3.14159265) x -= 6.28318531;

				if (x < 0) {
					sin = 1.27323954 * x + .405284735 * x * x;
					if (sin < 0) sin = .225 * (sin *-sin - sin) + sin;
					else sin = .225 * (sin * sin - sin) + sin;
				} else {
					sin = 1.27323954 * x - 0.405284735 * x * x;
					if (sin < 0) sin = .225 * (sin *-sin - sin) + sin;
					else sin = .225 * (sin * sin - sin) + sin;
				}
				return sin;
			},
			cosHigh: function(x){
				var cos;
				x += 1.57079632;
				if (x >  3.14159265) x -= 6.28318531;
				if (x < 0) {
					cos = 1.27323954 * x + 0.405284735 * x * x;
					if (cos < 0) cos = .225 * (cos *-cos - cos) + cos;
					else cos = .225 * (cos * cos - cos) + cos;
				} else {
					cos = 1.27323954 * x - 0.405284735 * x * x;
					if (cos < 0) cos = .225 * (cos *-cos - cos) + cos;
					else cos = .225 * (cos * cos - cos) + cos;
				}
				return cos;
			},
			sinLow: function(x){
				if (x < -3.14159265) x += 6.28318531;
				else if (x >  3.14159265) x -= 6.28318531;
				if (x < 0) return 1.27323954 * x + .405284735 * x * x;
				else return 1.27323954 * x - 0.405284735 * x * x;
			},
			cosLow: function(x){
				x += 1.57079632;
				if (x >  3.14159265) x -= 6.28318531;
				if (x < 0) return 1.27323954 * x + 0.405284735 * x * x
				else return 1.27323954 * x - 0.405284735 * x * x;
			}
		}

		return FTrig;
	})();

	if (typeof module !== 'undefined' && typeof module.exports !== 'undefined')
		module.exports = FTrig;
	else if (typeof define === 'function' && define.amd)
		define([], function() {
			return FTrig;
		});
	else window.FTrig = FTrig;
})();