text: /**
   * @author mr.doob / http://mrdoob.com/
   * @author supereggbert / http://www.paulbrunt.co.uk/
   * @author philogb / http://blog.thejit.org/
   * @author jordi_ros / http://plattsoft.com
   * @author D1plo1d / http://github.com/D1plo1d
   * @author alteredq / http://alteredqualia.com/
   * @author mikael emtinger / http://gomo.se/
   * @author timknip / http://www.floorplanner.com/
   */
  
  THREE.Matrix4 = function ( n11, n12, n13, n14, n21, n22, n23, n24, n31, n32, n33, n34, n41, n42, n43, n44 ) {
  
  	this.set(
  
  		n11 || 1, n12 || 0, n13 || 0, n14 || 0,
  		n21 || 0, n22 || 1, n23 || 0, n24 || 0,
  		n31 || 0, n32 || 0, n33 || 1, n34 || 0,
  		n41 || 0, n42 || 0, n43 || 0, n44 || 1
  
  	);
  
  	this.flat = new Array( 16 );
  	this.m33 = new THREE.Matrix3();
  
  };
  
  THREE.Matrix4.prototype = {
  
  	constructor: THREE.Matrix4,
  
  	set: function ( n11, n12, n13, n14, n21, n22, n23, n24, n31, n32, n33, n34, n41, n42, n43, n44 ) {
  
  		this.n11 = n11; this.n12 = n12; this.n13 = n13; this.n14 = n14;
  		this.n21 = n21; this.n22 = n22; this.n23 = n23; this.n24 = n24;
  		this.n31 = n31; this.n32 = n32; this.n33 = n33; this.n34 = n34;
  		this.n41 = n41; this.n42 = n42; this.n43 = n43; this.n44 = n44;
  
  		return this;
  
  	},
  
  	identity: function () {
  
  		this.set(
  
  			1, 0, 0, 0,
  			0, 1, 0, 0,
  			0, 0, 1, 0,
  			0, 0, 0, 1
  
  		);
  
  		return this;
  
  	},
  
  	copy: function ( m ) {
  
  		this.set(
  
  			m.n11, m.n12, m.n13, m.n14,
  			m.n21, m.n22, m.n23, m.n24,
  			m.n31, m.n32, m.n33, m.n34,
  			m.n41, m.n42, m.n43, m.n44
  
  		);
  
  		return this;
  
  	},
  
  	lookAt: function ( eye, center, up ) {
  
  		var x = THREE.Matrix4.__v1, y = THREE.Matrix4.__v2, z = THREE.Matrix4.__v3;
  
  		z.sub( eye, center ).normalize();
  
  		if ( z.length() === 0 ) {
  
  			z.z = 1;
  
  		}
  
  		x.cross( up, z ).normalize();
  
  		if ( x.length() === 0 ) {
  
  			z.x += 0.0001;
  			x.cross( up, z ).normalize();
  
  		}
  
  		y.cross( z, x ).normalize();
  
  
  		this.n11 = x.x; this.n12 = y.x; this.n13 = z.x;
  		this.n21 = x.y; this.n22 = y.y; this.n23 = z.y;
  		this.n31 = x.z; this.n32 = y.z; this.n33 = z.z;
  
  		return this;
  
  	},
  
  	multiplyVector3: function ( v ) {
  
  		var vx = v.x, vy = v.y, vz = v.z,
  		d = 1 / ( this.n41 * vx + this.n42 * vy + this.n43 * vz + this.n44 );
  
  		v.x = ( this.n11 * vx + this.n12 * vy + this.n13 * vz + this.n14 ) * d;
  		v.y = ( this.n21 * vx + this.n22 * vy + this.n23 * vz + this.n24 ) * d;
  		v.z = ( this.n31 * vx + this.n32 * vy + this.n33 * vz + this.n34 ) * d;
  
  		return v;
  
  	},
  
  	multiplyVector4: function ( v ) {
  
  		var vx = v.x, vy = v.y, vz = v.z, vw = v.w;
  
  		v.x = this.n11 * vx + this.n12 * vy + this.n13 * vz + this.n14 * vw;
  		v.y = this.n21 * vx + this.n22 * vy + this.n23 * vz + this.n24 * vw;
  		v.z = this.n31 * vx + this.n32 * vy + this.n33 * vz + this.n34 * vw;
  		v.w = this.n41 * vx + this.n42 * vy + this.n43 * vz + this.n44 * vw;
  
  		return v;
  
  	},
  
  	rotateAxis: function ( v ) {
  
  		var vx = v.x, vy = v.y, vz = v.z;
  
  		v.x = vx * this.n11 + vy * this.n12 + vz * this.n13;
  		v.y = vx * this.n21 + vy * this.n22 + vz * this.n23;
  		v.z = vx * this.n31 + vy * this.n32 + vz * this.n33;
  
  		v.normalize();
  
  		return v;
  
  	},
  
  	crossVector: function ( a ) {
  
  		var v = new THREE.Vector4();
  
  		v.x = this.n11 * a.x + this.n12 * a.y + this.n13 * a.z + this.n14 * a.w;
  		v.y = this.n21 * a.x + this.n22 * a.y + this.n23 * a.z + this.n24 * a.w;
  		v.z = this.n31 * a.x + this.n32 * a.y + this.n33 * a.z + this.n34 * a.w;
  
  		v.w = ( a.w ) ? this.n41 * a.x + this.n42 * a.y + this.n43 * a.z + this.n44 * a.w : 1;
  
  		return v;
  
  	},
  
  	multiply: function ( a, b ) {
  
  		var a11 = a.n11, a12 = a.n12, a13 = a.n13, a14 = a.n14,
  		a21 = a.n21, a22 = a.n22, a23 = a.n23, a24 = a.n24,
  		a31 = a.n31, a32 = a.n32, a33 = a.n33, a34 = a.n34,
  		a41 = a.n41, a42 = a.n42, a43 = a.n43, a44 = a.n44,
  
  		b11 = b.n11, b12 = b.n12, b13 = b.n13, b14 = b.n14,
  		b21 = b.n21, b22 = b.n22, b23 = b.n23, b24 = b.n24,
  		b31 = b.n31, b32 = b.n32, b33 = b.n33, b34 = b.n34,
  		b41 = b.n41, b42 = b.n42, b43 = b.n43, b44 = b.n44;
  
  		this.n11 = a11 * b11 + a12 * b21 + a13 * b31 + a14 * b41;
  		this.n12 = a11 * b12 + a12 * b22 + a13 * b32 + a14 * b42;
  		this.n13 = a11 * b13 + a12 * b23 + a13 * b33 + a14 * b43;
  		this.n14 = a11 * b14 + a12 * b24 + a13 * b34 + a14 * b44;
  
  		this.n21 = a21 * b11 + a22 * b21 + a23 * b31 + a24 * b41;
  		this.n22 = a21 * b12 + a22 * b22 + a23 * b32 + a24 * b42;
  		this.n23 = a21 * b13 + a22 * b23 + a23 * b33 + a24 * b43;
  		this.n24 = a21 * b14 + a22 * b24 + a23 * b34 + a24 * b44;
  
  		this.n31 = a31 * b11 + a32 * b21 + a33 * b31 + a34 * b41;
  		this.n32 = a31 * b12 + a32 * b22 + a33 * b32 + a34 * b42;
  		this.n33 = a31 * b13 + a32 * b23 + a33 * b33 + a34 * b43;
  		this.n34 = a31 * b14 + a32 * b24 + a33 * b34 + a34 * b44;
  
  		this.n41 = a41 * b11 + a42 * b21 + a43 * b31 + a44 * b41;
  		this.n42 = a41 * b12 + a42 * b22 + a43 * b32 + a44 * b42;
  		this.n43 = a41 * b13 + a42 * b23 + a43 * b33 + a44 * b43;
  		this.n44 = a41 * b14 + a42 * b24 + a43 * b34 + a44 * b44;
  
  		return this;
  
  	},
  
  	multiplyToArray: function ( a, b, r ) {
  
  		this.multiply( a, b );
  
  		r[ 0 ] = this.n11; r[ 1 ] = this.n21; r[ 2 ] = this.n31; r[ 3 ] = this.n41;
  		r[ 4 ] = this.n12; r[ 5 ] = this.n22; r[ 6 ] = this.n32; r[ 7 ] = this.n42;
  		r[ 8 ]  = this.n13; r[ 9 ]  = this.n23; r[ 10 ] = this.n33; r[ 11 ] = this.n43;
  		r[ 12 ] = this.n14; r[ 13 ] = this.n24; r[ 14 ] = this.n34; r[ 15 ] = this.n44;
  
  		return this;
  
  	},
  
  	multiplySelf: function ( m ) {
  
  		this.multiply( this, m );
  
  		return this;
  
  	},
  
  	multiplyScalar: function ( s ) {
  
  		this.n11 *= s; this.n12 *= s; this.n13 *= s; this.n14 *= s;
  		this.n21 *= s; this.n22 *= s; this.n23 *= s; this.n24 *= s;
  		this.n31 *= s; this.n32 *= s; this.n33 *= s; this.n34 *= s;
  		this.n41 *= s; this.n42 *= s; this.n43 *= s; this.n44 *= s;
  
  		return this;
  
  	},
  
  	determinant: function () {
  
  		var n11 = this.n11, n12 = this.n12, n13 = this.n13, n14 = this.n14,
  		n21 = this.n21, n22 = this.n22, n23 = this.n23, n24 = this.n24,
  		n31 = this.n31, n32 = this.n32, n33 = this.n33, n34 = this.n34,
  		n41 = this.n41, n42 = this.n42, n43 = this.n43, n44 = this.n44;
  
  		//TODO: make this more efficient
  		//( based on http://www.euclideanspace.com/maths/algebra/matrix/functions/inverse/fourD/index.htm )
  		return (
  			n14 * n23 * n32 * n41-
  			n13 * n24 * n32 * n41-
  			n14 * n22 * n33 * n41+
  			n12 * n24 * n33 * n41+
  
  			n13 * n22 * n34 * n41-
  			n12 * n23 * n34 * n41-
  			n14 * n23 * n31 * n42+
  			n13 * n24 * n31 * n42+
  
  			n14 * n21 * n33 * n42-
  			n11 * n24 * n33 * n42-
  			n13 * n21 * n34 * n42+
  			n11 * n23 * n34 * n42+
  
  			n14 * n22 * n31 * n43-
  			n12 * n24 * n31 * n43-
  			n14 * n21 * n32 * n43+
  			n11 * n24 * n32 * n43+
  
  			n12 * n21 * n34 * n43-
  			n11 * n22 * n34 * n43-
  			n13 * n22 * n31 * n44+
  			n12 * n23 * n31 * n44+
  
  			n13 * n21 * n32 * n44-
  			n11 * n23 * n32 * n44-
  			n12 * n21 * n33 * n44+
  			n11 * n22 * n33 * n44
  		);
  
  	},
  
  	transpose: function () {
  
  		var tmp;
  
  		tmp = this.n21; this.n21 = this.n12; this.n12 = tmp;
  		tmp = this.n31; this.n31 = this.n13; this.n13 = tmp;
  		tmp = this.n32; this.n32 = this.n23; this.n23 = tmp;
  
  		tmp = this.n41; this.n41 = this.n14; this.n14 = tmp;
  		tmp = this.n42; this.n42 = this.n24; this.n24 = tmp;
  		tmp = this.n43; this.n43 = this.n34; this.n43 = tmp;
  
  		return this;
  
  	},
  
  	clone: function () {
  
  		var m = new THREE.Matrix4();
  
  		m.n11 = this.n11; m.n12 = this.n12; m.n13 = this.n13; m.n14 = this.n14;
  		m.n21 = this.n21; m.n22 = this.n22; m.n23 = this.n23; m.n24 = this.n24;
  		m.n31 = this.n31; m.n32 = this.n32; m.n33 = this.n33; m.n34 = this.n34;
  		m.n41 = this.n41; m.n42 = this.n42; m.n43 = this.n43; m.n44 = this.n44;
  
  		return m;
  
  	},
  
  	flatten: function () {
  
  		this.flat[ 0 ] = this.n11; this.flat[ 1 ] = this.n21; this.flat[ 2 ] = this.n31; this.flat[ 3 ] = this.n41;
  		this.flat[ 4 ] = this.n12; this.flat[ 5 ] = this.n22; this.flat[ 6 ] = this.n32; this.flat[ 7 ] = this.n42;
  		this.flat[ 8 ]  = this.n13; this.flat[ 9 ]  = this.n23; this.flat[ 10 ] = this.n33; this.flat[ 11 ] = this.n43;
  		this.flat[ 12 ] = this.n14; this.flat[ 13 ] = this.n24; this.flat[ 14 ] = this.n34; this.flat[ 15 ] = this.n44;
  
  		return this.flat;
  
  	},
  
  	flattenToArray: function ( flat ) {
  
  		flat[ 0 ] = this.n11; flat[ 1 ] = this.n21; flat[ 2 ] = this.n31; flat[ 3 ] = this.n41;
  		flat[ 4 ] = this.n12; flat[ 5 ] = this.n22; flat[ 6 ] = this.n32; flat[ 7 ] = this.n42;
  		flat[ 8 ]  = this.n13; flat[ 9 ]  = this.n23; flat[ 10 ] = this.n33; flat[ 11 ] = this.n43;
  		flat[ 12 ] = this.n14; flat[ 13 ] = this.n24; flat[ 14 ] = this.n34; flat[ 15 ] = this.n44;
  
  		return flat;
  
  	},
  
  	flattenToArrayOffset: function( flat, offset ) {
  
  		flat[ offset ] = this.n11;
  		flat[ offset + 1 ] = this.n21;
  		flat[ offset + 2 ] = this.n31;
  		flat[ offset + 3 ] = this.n41;
  
  		flat[ offset + 4 ] = this.n12;
  		flat[ offset + 5 ] = this.n22;
  		flat[ offset + 6 ] = this.n32;
  		flat[ offset + 7 ] = this.n42;
  
  		flat[ offset + 8 ]  = this.n13;
  		flat[ offset + 9 ]  = this.n23;
  		flat[ offset + 10 ] = this.n33;
  		flat[ offset + 11 ] = this.n43;
  
  		flat[ offset + 12 ] = this.n14;
  		flat[ offset + 13 ] = this.n24;
  		flat[ offset + 14 ] = this.n34;
  		flat[ offset + 15 ] = this.n44;
  
  		return flat;
  
  	},
  
  	setTranslation: function( x, y, z ) {
  
  		this.set(
  
  			1, 0, 0, x,
  			0, 1, 0, y,
  			0, 0, 1, z,
  			0, 0, 0, 1
  
  		);
  
  		return this;
  
  	},
  
  	setScale: function ( x, y, z ) {
  
  		this.set(
  
  			x, 0, 0, 0,
  			0, y, 0, 0,
  			0, 0, z, 0,
  			0, 0, 0, 1
  
  		);
  
  		return this;
  
  	},
  
  	setRotationX: function ( theta ) {
  
  		var c = Math.cos( theta ), s = Math.sin( theta );
  
  		this.set(
  
  			1, 0,  0, 0,
  			0, c, -s, 0,
  			0, s,  c, 0,
  			0, 0,  0, 1
  
  		);
  
  		return this;
  
  	},
  
  	setRotationY: function( theta ) {
  
  		var c = Math.cos( theta ), s = Math.sin( theta );
  
  		this.set(
  
  			 c, 0, s, 0,
  			 0, 1, 0, 0,
  			-s, 0, c, 0,
  			 0, 0, 0, 1
  
  		);
  
  		return this;
  
  	},
  
  	setRotationZ: function( theta ) {
  
  		var c = Math.cos( theta ), s = Math.sin( theta );
  
  		this.set(
  
  			c, -s, 0, 0,
  			s,  c, 0, 0,
  			0,  0, 1, 0,
  			0,  0, 0, 1
  
  		);
  
  		return this;
  
  	},
  
  	setRotationAxis: function( axis, angle ) {
  
  		// Based on http://www.gamedev.net/reference/articles/article1199.asp
  
  		var c = Math.cos( angle ),
  		s = Math.sin( angle ),
  		t = 1 - c,
  		x = axis.x, y = axis.y, z = axis.z,
  		tx = t * x, ty = t * y;
  
  		this.set(
  
  		 	tx * x + c, tx * y - s * z, tx * z + s * y, 0,
  			tx * y + s * z, ty * y + c, ty * z - s * x, 0,
  			tx * z - s * y, ty * z + s * x, t * z * z + c, 0,
  			0, 0, 0, 1
  
  		);
  
  		 return this;
  
  	},
  
  	setPosition: function( v ) {
  
  		this.n14 = v.x;
  		this.n24 = v.y;
  		this.n34 = v.z;
  
  		return this;
  
  	},
  
  	getPosition: function() {
  
  		if ( ! this.position ) {
  
  			this.position = new THREE.Vector3();
  
  		}
  
  		this.position.set( this.n14, this.n24, this.n34 );
  
  		return this.position;
  
  	},
  
  	getColumnX: function() {
  
  		if ( ! this.columnX ) {
  
  			this.columnX = new THREE.Vector3();
  
  		}
  
  		this.columnX.set( this.n11, this.n21, this.n31 );
  
  		return this.columnX;
  	},
  
  	getColumnY: function() {
  
  		if ( ! this.columnY ) {
  
  			this.columnY = new THREE.Vector3();
  
  		}
  
  		this.columnY.set( this.n12, this.n22, this.n32 );
  
  		return this.columnY;
  
  	},
  
  	getColumnZ: function() {
  
  		if ( ! this.columnZ ) {
  
  			this.columnZ = new THREE.Vector3();
  
  		}
  
  		this.columnZ.set( this.n13, this.n23, this.n33 );
  
  		return this.columnZ;
  
  	},
  
  	setRotationFromEuler: function( v, order ) {
  
  		var x = v.x, y = v.y, z = v.z,
  		a = Math.cos( x ), b = Math.sin( x ),
  		c = Math.cos( y ), d = Math.sin( y ),
  		e = Math.cos( z ), f = Math.sin( z );
  
  		switch ( order ) {
  
  			case 'YXZ':
  
  				var ce = c * e, cf = c * f, de = d * e, df = d * f;
  
  				this.n11 = ce + df * b;
  				this.n12 = de * b - cf;
  				this.n13 = a * d;
  
  				this.n21 = a * f;
  				this.n22 = a * e;
  				this.n23 = - b;
  
  				this.n31 = cf * b - de;
  				this.n32 = df + ce * b;
  				this.n33 = a * c;
  				break;
  
  			case 'ZXY':
  
  				var ce = c * e, cf = c * f, de = d * e, df = d * f;
  
  				this.n11 = ce - df * b;
  				this.n12 = - a * f;
  				this.n13 = de + cf * b;
  
  				this.n21 = cf + de * b;
  				this.n22 = a * e;
  				this.n23 = df - ce * b;
  
  				this.n31 = - a * d;
  				this.n32 = b;
  				this.n33 = a * c;
  				break;
  
  			case 'ZYX':
  
  				var ae = a * e, af = a * f, be = b * e, bf = b * f;
  
  				this.n11 = c * e;
  				this.n12 = be * d - af;
  				this.n13 = ae * d + bf;
  
  				this.n21 = c * f;
  				this.n22 = bf * d + ae;
  				this.n23 = af * d - be;
  
  				this.n31 = - d;
  				this.n32 = b * c;
  				this.n33 = a * c;
  				break;
  
  			case 'YZX':
  
  				var ac = a * c, ad = a * d, bc = b * c, bd = b * d;
  
  				this.n11 = c * e;
  				this.n12 = bd - ac * f;
  				this.n13 = bc * f + ad;
  
  				this.n21 = f;
  				this.n22 = a * e;
  				this.n23 = - b * e;
  
  				this.n31 = - d * e;
  				this.n32 = ad * f + bc;
  				this.n33 = ac - bd * f;
  				break;
  
  			case 'XZY':
  
  				var ac = a * c, ad = a * d, bc = b * c, bd = b * d;
  
  				this.n11 = c * e;
  				this.n12 = - f;
  				this.n13 = d * e;
  
  				this.n21 = ac * f + bd;
  				this.n22 = a * e;
  				this.n23 = ad * f - bc;
  
  				this.n31 = bc * f - ad;
  				this.n32 = b * e;
  				this.n33 = bd * f + ac;
  				break;
  
  			default: // 'XYZ'
  
  				var ae = a * e, af = a * f, be = b * e, bf = b * f;
  
  				this.n11 = c * e;
  				this.n12 = - c * f;
  				this.n13 = d;
  
  				this.n21 = af + be * d;
  				this.n22 = ae - bf * d;
  				this.n23 = - b * c;
  
  				this.n31 = bf - ae * d;
  				this.n32 = be + af * d;
  				this.n33 = a * c;
  				break;
  
  		}
  
  		return this;
  
  	},
  
  
  	setRotationFromQuaternion: function( q ) {
  
  		var x = q.x, y = q.y, z = q.z, w = q.w,
  		x2 = x + x, y2 = y + y, z2 = z + z,
  		xx = x * x2, xy = x * y2, xz = x * z2,
  		yy = y * y2, yz = y * z2, zz = z * z2,
  		wx = w * x2, wy = w * y2, wz = w * z2;
  
  		this.n11 = 1 - ( yy + zz );
  		this.n12 = xy - wz;
  		this.n13 = xz + wy;
  
  		this.n21 = xy + wz;
  		this.n22 = 1 - ( xx + zz );
  		this.n23 = yz - wx;
  
  		this.n31 = xz - wy;
  		this.n32 = yz + wx;
  		this.n33 = 1 - ( xx + yy );
  
  		return this;
  
  	},
  
  	scale: function ( v ) {
  
  		var x = v.x, y = v.y, z = v.z;
  
  		this.n11 *= x; this.n12 *= y; this.n13 *= z;
  		this.n21 *= x; this.n22 *= y; this.n23 *= z;
  		this.n31 *= x; this.n32 *= y; this.n33 *= z;
  		this.n41 *= x; this.n42 *= y; this.n43 *= z;
  
  		return this;
  
  	},
  
  	compose: function ( translation, rotation, scale ) {
  
  		var mRotation = THREE.Matrix4.__m1;
  		var mScale = THREE.Matrix4.__m2;
  
  		mRotation.identity();
  		mRotation.setRotationFromQuaternion( rotation );
  
  		mScale.setScale( scale.x, scale.y, scale.z );
  
  		this.multiply( mRotation, mScale );
  
  		this.n14 = translation.x;
  		this.n24 = translation.y;
  		this.n34 = translation.z;
  
  		return this;
  
  	},
  
  	decompose: function ( translation, rotation, scale ) {
  
  		// grab the axis vectors
  
  		var x = THREE.Matrix4.__v1;
  		var y = THREE.Matrix4.__v2;
  		var z = THREE.Matrix4.__v3;
  
  		x.set( this.n11, this.n21, this.n31 );
  		y.set( this.n12, this.n22, this.n32 );
  		z.set( this.n13, this.n23, this.n33 );
  
  		translation = ( translation instanceof THREE.Vector3 ) ? translation : new THREE.Vector3();
  		rotation = ( rotation instanceof THREE.Quaternion ) ? rotation : new THREE.Quaternion();
  		scale = ( scale instanceof THREE.Vector3 ) ? scale : new THREE.Vector3();
  
  		scale.x = x.length();
  		scale.y = y.length();
  		scale.z = z.length();
  
  		translation.x = this.n14;
  		translation.y = this.n24;
  		translation.z = this.n34;
  
  		// scale the rotation part
  
  		var matrix = THREE.Matrix4.__m1;
  
  		matrix.copy( this );
  
  		matrix.n11 /= scale.x;
  		matrix.n21 /= scale.x;
  		matrix.n31 /= scale.x;
  
  		matrix.n12 /= scale.y;
  		matrix.n22 /= scale.y;
  		matrix.n32 /= scale.y;
  
  		matrix.n13 /= scale.z;
  		matrix.n23 /= scale.z;
  		matrix.n33 /= scale.z;
  
  		rotation.setFromRotationMatrix( matrix );
  
  		return [ translation, rotation, scale ];
  
  	},
  
  	extractPosition: function ( m ) {
  
  		this.n14 = m.n14;
  		this.n24 = m.n24;
  		this.n34 = m.n34;
  
  	},
  
  	extractRotation: function ( m, s ) {
  
  		var invScaleX = 1 / s.x, invScaleY = 1 / s.y, invScaleZ = 1 / s.z;
  
  		this.n11 = m.n11 * invScaleX;
  		this.n21 = m.n21 * invScaleX;
  		this.n31 = m.n31 * invScaleX;
  
  		this.n12 = m.n12 * invScaleY;
  		this.n22 = m.n22 * invScaleY;
  		this.n32 = m.n32 * invScaleY;
  
  		this.n13 = m.n13 * invScaleZ;
  		this.n23 = m.n23 * invScaleZ;
  		this.n33 = m.n33 * invScaleZ;
  
  	}
  
  };
  
  THREE.Matrix4.makeInvert = function ( m1, m2 ) {
  
  	// based on http://www.euclideanspace.com/maths/algebra/matrix/functions/inverse/fourD/index.htm
  
  	var n11 = m1.n11, n12 = m1.n12, n13 = m1.n13, n14 = m1.n14,
  	n21 = m1.n21, n22 = m1.n22, n23 = m1.n23, n24 = m1.n24,
  	n31 = m1.n31, n32 = m1.n32, n33 = m1.n33, n34 = m1.n34,
  	n41 = m1.n41, n42 = m1.n42, n43 = m1.n43, n44 = m1.n44;
  
  	if ( m2 === undefined ) m2 = new THREE.Matrix4();
  
  	m2.n11 = n23*n34*n42 - n24*n33*n42 + n24*n32*n43 - n22*n34*n43 - n23*n32*n44 + n22*n33*n44;
  	m2.n12 = n14*n33*n42 - n13*n34*n42 - n14*n32*n43 + n12*n34*n43 + n13*n32*n44 - n12*n33*n44;
  	m2.n13 = n13*n24*n42 - n14*n23*n42 + n14*n22*n43 - n12*n24*n43 - n13*n22*n44 + n12*n23*n44;
  	m2.n14 = n14*n23*n32 - n13*n24*n32 - n14*n22*n33 + n12*n24*n33 + n13*n22*n34 - n12*n23*n34;
  	m2.n21 = n24*n33*n41 - n23*n34*n41 - n24*n31*n43 + n21*n34*n43 + n23*n31*n44 - n21*n33*n44;
  	m2.n22 = n13*n34*n41 - n14*n33*n41 + n14*n31*n43 - n11*n34*n43 - n13*n31*n44 + n11*n33*n44;
  	m2.n23 = n14*n23*n41 - n13*n24*n41 - n14*n21*n43 + n11*n24*n43 + n13*n21*n44 - n11*n23*n44;
  	m2.n24 = n13*n24*n31 - n14*n23*n31 + n14*n21*n33 - n11*n24*n33 - n13*n21*n34 + n11*n23*n34;
  	m2.n31 = n22*n34*n41 - n24*n32*n41 + n24*n31*n42 - n21*n34*n42 - n22*n31*n44 + n21*n32*n44;
  	m2.n32 = n14*n32*n41 - n12*n34*n41 - n14*n31*n42 + n11*n34*n42 + n12*n31*n44 - n11*n32*n44;
  	m2.n33 = n13*n24*n41 - n14*n22*n41 + n14*n21*n42 - n11*n24*n42 - n12*n21*n44 + n11*n22*n44;
  	m2.n34 = n14*n22*n31 - n12*n24*n31 - n14*n21*n32 + n11*n24*n32 + n12*n21*n34 - n11*n22*n34;
  	m2.n41 = n23*n32*n41 - n22*n33*n41 - n23*n31*n42 + n21*n33*n42 + n22*n31*n43 - n21*n32*n43;
  	m2.n42 = n12*n33*n41 - n13*n32*n41 + n13*n31*n42 - n11*n33*n42 - n12*n31*n43 + n11*n32*n43;
  	m2.n43 = n13*n22*n41 - n12*n23*n41 - n13*n21*n42 + n11*n23*n42 + n12*n21*n43 - n11*n22*n43;
  	m2.n44 = n12*n23*n31 - n13*n22*n31 + n13*n21*n32 - n11*n23*n32 - n12*n21*n33 + n11*n22*n33;
  	m2.multiplyScalar( 1 / m1.determinant() );
  
  	return m2;
  
  };
  
  THREE.Matrix4.makeInvert3x3 = function ( m1 ) {
  
  	// input:  THREE.Matrix4, output: THREE.Matrix3
  	// ( based on http://code.google.com/p/webgl-mjs/ )
  
  	var m33 = m1.m33, m33m = m33.m,
  	a11 =   m1.n33 * m1.n22 - m1.n32 * m1.n23,
  	a21 = - m1.n33 * m1.n21 + m1.n31 * m1.n23,
  	a31 =   m1.n32 * m1.n21 - m1.n31 * m1.n22,
  	a12 = - m1.n33 * m1.n12 + m1.n32 * m1.n13,
  	a22 =   m1.n33 * m1.n11 - m1.n31 * m1.n13,
  	a32 = - m1.n32 * m1.n11 + m1.n31 * m1.n12,
  	a13 =   m1.n23 * m1.n12 - m1.n22 * m1.n13,
  	a23 = - m1.n23 * m1.n11 + m1.n21 * m1.n13,
  	a33 =   m1.n22 * m1.n11 - m1.n21 * m1.n12,
  
  	det = m1.n11 * a11 + m1.n21 * a12 + m1.n31 * a13,
  
  	idet;
  
  	// no inverse
  	if ( det == 0 ) {
  
  		console.error( 'THREE.Matrix4.makeInvert3x3: Matrix not invertible.' );
  
  	}
  
  	idet = 1.0 / det;
  
  	m33m[ 0 ] = idet * a11; m33m[ 1 ] = idet * a21; m33m[ 2 ] = idet * a31;
  	m33m[ 3 ] = idet * a12; m33m[ 4 ] = idet * a22; m33m[ 5 ] = idet * a32;
  	m33m[ 6 ] = idet * a13; m33m[ 7 ] = idet * a23; m33m[ 8 ] = idet * a33;
  
  	return m33;
  
  }
  
  THREE.Matrix4.makeFrustum = function ( left, right, bottom, top, near, far ) {
  
  	var m, x, y, a, b, c, d;
  
  	m = new THREE.Matrix4();
  
  	x = 2 * near / ( right - left );
  	y = 2 * near / ( top - bottom );
  
  	a = ( right + left ) / ( right - left );
  	b = ( top + bottom ) / ( top - bottom );
  	c = - ( far + near ) / ( far - near );
  	d = - 2 * far * near / ( far - near );
  
  	m.n11 = x;  m.n12 = 0;  m.n13 = a;   m.n14 = 0;
  	m.n21 = 0;  m.n22 = y;  m.n23 = b;   m.n24 = 0;
  	m.n31 = 0;  m.n32 = 0;  m.n33 = c;   m.n34 = d;
  	m.n41 = 0;  m.n42 = 0;  m.n43 = - 1; m.n44 = 0;
  
  	return m;
  
  };
  
  THREE.Matrix4.makePerspective = function ( fov, aspect, near, far ) {
  
  	var ymax, ymin, xmin, xmax;
  
  	ymax = near * Math.tan( fov * Math.PI / 360 );
  	ymin = - ymax;
  	xmin = ymin * aspect;
  	xmax = ymax * aspect;
  
  	return THREE.Matrix4.makeFrustum( xmin, xmax, ymin, ymax, near, far );
  
  };
  
  THREE.Matrix4.makeOrtho = function ( left, right, top, bottom, near, far ) {
  
  	var m, x, y, z, w, h, p;
  
  	m = new THREE.Matrix4();
  
  	w = right - left;
  	h = top - bottom;
  	p = far - near;
  
  	x = ( right + left ) / w;
  	y = ( top + bottom ) / h;
  	z = ( far + near ) / p;
  
  	m.n11 = 2 / w; m.n12 = 0;     m.n13 = 0;      m.n14 = -x;
  	m.n21 = 0;     m.n22 = 2 / h; m.n23 = 0;      m.n24 = -y;
  	m.n31 = 0;     m.n32 = 0;     m.n33 = -2 / p; m.n34 = -z;
  	m.n41 = 0;     m.n42 = 0;     m.n43 = 0;      m.n44 = 1;
  
  	return m;
  
  };
  
  THREE.Matrix4.__v1 = new THREE.Vector3();
  THREE.Matrix4.__v2 = new THREE.Vector3();
  THREE.Matrix4.__v3 = new THREE.Vector3();
  
  THREE.Matrix4.__m1 = new THREE.Matrix4();
  THREE.Matrix4.__m2 = new THREE.Matrix4();
  