source: other-projects/playing-in-the-street/summer-2013/trunk/Playing-in-the-Street-WPF/Content/Web/mrdoob-three.js-4862f5f/src/math/Matrix3.js@ 28897

/**
 * @author alteredq / http://alteredqualia.com/
 * @author WestLangley / http://github.com/WestLangley
 * @author bhouston / http://exocortex.com
 */

THREE.Matrix3 = function ( n11, n12, n13, n21, n22, n23, n31, n32, n33 ) {

    this.elements = new Float32Array(9);

    this.set(

        ( n11 !== undefined ) ? n11 : 1, n12 || 0, n13 || 0,
        n21 || 0, ( n22 !== undefined ) ? n22 : 1, n23 || 0,
        n31 || 0, n32 || 0, ( n33 !== undefined ) ? n33 : 1

    );
};

THREE.Matrix3.prototype = {

    constructor: THREE.Matrix3,

    set: function ( n11, n12, n13, n21, n22, n23, n31, n32, n33 ) {

        var te = this.elements;

        te[0] = n11; te[3] = n12; te[6] = n13;
        te[1] = n21; te[4] = n22; te[7] = n23;
        te[2] = n31; te[5] = n32; te[8] = n33;

        return this;

    },

    identity: function () {

        this.set(

            1, 0, 0,
            0, 1, 0,
            0, 0, 1

        );

        return this;

    },

    copy: function ( m ) {

        var me = m.elements;

        this.set(

            me[0], me[3], me[6],
            me[1], me[4], me[7],
            me[2], me[5], me[8]

        );

        return this;

    },

    multiplyVector3: function ( vector ) {

        console.warn( 'DEPRECATED: Matrix3\'s .multiplyVector3() has been removed. Use vector.applyMatrix3( matrix ) instead.' );
        return vector.applyMatrix3( this );

    },

    multiplyVector3Array: function() {

        var v1 = new THREE.Vector3();

        return function ( a ) {

            for ( var i = 0, il = a.length; i < il; i += 3 ) {

                v1.x = a[ i ];
                v1.y = a[ i + 1 ];
                v1.z = a[ i + 2 ];

                v1.applyMatrix3(this);

                a[ i ]     = v1.x;
                a[ i + 1 ] = v1.y;
                a[ i + 2 ] = v1.z;

            }

            return a;

        };

    }(),

    multiplyScalar: function ( s ) {

        var te = this.elements;

        te[0] *= s; te[3] *= s; te[6] *= s;
        te[1] *= s; te[4] *= s; te[7] *= s;
        te[2] *= s; te[5] *= s; te[8] *= s;

        return this;

    },

    determinant: function () {

        var te = this.elements;

        var a = te[0], b = te[1], c = te[2],
            d = te[3], e = te[4], f = te[5],
            g = te[6], h = te[7], i = te[8];

        return a*e*i - a*f*h - b*d*i + b*f*g + c*d*h - c*e*g;

    },

    getInverse: function ( matrix, throwOnInvertible ) {

        // input: THREE.Matrix4
        // ( based on http://code.google.com/p/webgl-mjs/ )

        var me = matrix.elements;
        var te = this.elements;

        te[ 0 ] =   me[10] * me[5] - me[6] * me[9];
        te[ 1 ] = - me[10] * me[1] + me[2] * me[9];
        te[ 2 ] =   me[6] * me[1] - me[2] * me[5];
        te[ 3 ] = - me[10] * me[4] + me[6] * me[8];
        te[ 4 ] =   me[10] * me[0] - me[2] * me[8];
        te[ 5 ] = - me[6] * me[0] + me[2] * me[4];
        te[ 6 ] =   me[9] * me[4] - me[5] * me[8];
        te[ 7 ] = - me[9] * me[0] + me[1] * me[8];
        te[ 8 ] =   me[5] * me[0] - me[1] * me[4];

        var det = me[ 0 ] * te[ 0 ] + me[ 1 ] * te[ 3 ] + me[ 2 ] * te[ 6 ];

        // no inverse

        if ( det === 0 ) {

            var msg = "Matrix3.getInverse(): can't invert matrix, determinant is 0";

            if ( throwOnInvertible || false ) {

                throw new Error( msg );

            } else {

                console.warn( msg );

            }

            this.identity();

            return this;

        }

        this.multiplyScalar( 1.0 / det );

        return this;

    },

    transpose: function () {

        var tmp, m = this.elements;

        tmp = m[1]; m[1] = m[3]; m[3] = tmp;
        tmp = m[2]; m[2] = m[6]; m[6] = tmp;
        tmp = m[5]; m[5] = m[7]; m[7] = tmp;

        return this;

    },

    getNormalMatrix: function ( m ) {

        // input: THREE.Matrix4

        this.getInverse( m ).transpose();

        return this;

    },

    transposeIntoArray: function ( r ) {

        var m = this.elements;

        r[ 0 ] = m[ 0 ];
        r[ 1 ] = m[ 3 ];
        r[ 2 ] = m[ 6 ];
        r[ 3 ] = m[ 1 ];
        r[ 4 ] = m[ 4 ];
        r[ 5 ] = m[ 7 ];
        r[ 6 ] = m[ 2 ];
        r[ 7 ] = m[ 5 ];
        r[ 8 ] = m[ 8 ];

        return this;

    },

    fromArray: function ( array ) {

        this.elements.set( array );

        return this;

    },

    toArray: function () {

        var te = this.elements;

        return [
            te[ 0 ], te[ 1 ], te[ 2 ],
            te[ 3 ], te[ 4 ], te[ 5 ],
            te[ 6 ], te[ 7 ], te[ 8 ]
        ];

    },

    clone: function () {

        var te = this.elements;

        return new THREE.Matrix3(

            te[0], te[3], te[6],
            te[1], te[4], te[7],
            te[2], te[5], te[8]

        );

    }

};