three.js/src/math/Math.js

/**
 * @author alteredq / http://alteredqualia.com/
 * @author mrdoob / http://mrdoob.com/
 */

THREE.Math = {

	generateUUID: function () {

		// http://www.broofa.com/Tools/Math.uuid.htm

		var chars = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'.split( '' );
		var uuid = new Array( 36 );
		var rnd = 0, r;

		return function () {

			for ( var i = 0; i < 36; i ++ ) {

				if ( i == 8 || i == 13 || i == 18 || i == 23 ) {

					uuid[ i ] = '-';

				} else if ( i == 14 ) {

					uuid[ i ] = '4';

				} else {

					if ( rnd <= 0x02 ) rnd = 0x2000000 + ( Math.random() * 0x1000000 ) | 0;
					r = rnd & 0xf;
					rnd = rnd >> 4;
					uuid[ i ] = chars[ ( i == 19 ) ? ( r & 0x3 ) | 0x8 : r ];

				}
			}

			return uuid.join( '' );

		};

	}(),

	// Clamp value to range <a, b>

	clamp: function ( x, a, b ) {

		return ( x < a ) ? a : ( ( x > b ) ? b : x );

	},

	// Clamp value to range <a, inf)

	clampBottom: function ( x, a ) {

		return x < a ? a : x;

	},

	// Linear mapping from range <a1, a2> to range <b1, b2>

	mapLinear: function ( x, a1, a2, b1, b2 ) {

		return b1 + ( x - a1 ) * ( b2 - b1 ) / ( a2 - a1 );

	},

	// http://en.wikipedia.org/wiki/Smoothstep

	smoothstep: function ( x, min, max ) {

		if ( x <= min ) return 0;
		if ( x >= max ) return 1;

		x = ( x - min ) / ( max - min );

		return x * x * ( 3 - 2 * x );

	},

	smootherstep: function ( x, min, max ) {

		if ( x <= min ) return 0;
		if ( x >= max ) return 1;

		x = ( x - min ) / ( max - min );

		return x * x * x * ( x * ( x * 6 - 15 ) + 10 );

	},

	// Random float from <0, 1> with 16 bits of randomness
	// (standard Math.random() creates repetitive patterns when applied over larger space)

	random16: function () {

		return ( 65280 * Math.random() + 255 * Math.random() ) / 65535;

	},

	// Random integer from <low, high> interval

	randInt: function ( low, high ) {

		return Math.floor( this.randFloat( low, high ) );

	},

	// Random float from <low, high> interval

	randFloat: function ( low, high ) {

		return low + Math.random() * ( high - low );

	},

	// Random float from <-range/2, range/2> interval

	randFloatSpread: function ( range ) {

		return range * ( 0.5 - Math.random() );

	},

	degToRad: function () {

		var degreeToRadiansFactor = Math.PI / 180;

		return function ( degrees ) {

			return degrees * degreeToRadiansFactor;

		};

	}(),

	radToDeg: function () {

		var radianToDegreesFactor = 180 / Math.PI;

		return function ( radians ) {

			return radians * radianToDegreesFactor;

		};

	}(),

	isPowerOfTwo: function ( value ) {

		return ( value & ( value - 1 ) ) === 0 && value !== 0;

	},

	nextPowerOfTwo: function ( value ) {

		value --;
		value |= value >> 1;
		value |= value >> 2;
		value |= value >> 4;
		value |= value >> 8;
		value |= value >> 16;
		value ++;

		return value;

	}

};