Add equality and matrix multiplication methods to Matrix3

src/math/Matrix3.js

@@ -114,6 +114,62 @@ Object.assign( Matrix3.prototype, {
 
 	}(),
 
+	multiply: function ( m ) {
+
+		return this.multiplyMatrices( this, m );
+
+	},
+
+	premultiply: function ( m ) {
+
+		return this.multiplyMatrices( m, this );
+
+	},
+
+	multiplyMatrices: function ( a, b ) {
+
+		var ae = a.elements;
+		var be = b.elements;
+		var te = this.elements;
+
+		var a11 = ae[ 0 ], a12 = ae[ 3 ], a13 = ae[ 6 ];
+		var a21 = ae[ 1 ], a22 = ae[ 4 ], a23 = ae[ 7 ];
+		var a31 = ae[ 2 ], a32 = ae[ 5 ], a33 = ae[ 8 ];
+
+		var b11 = be[ 0 ], b12 = be[ 3 ], b13 = be[ 6 ];
+		var b21 = be[ 1 ], b22 = be[ 4 ], b23 = be[ 7 ];
+		var b31 = be[ 2 ], b32 = be[ 5 ], b33 = be[ 8 ];
+
+		te[ 0 ] = a11 * b11 + a12 * b21 + a13 * b31;
+		te[ 3 ] = a11 * b12 + a12 * b22 + a13 * b32;
+		te[ 6 ] = a11 * b13 + a12 * b23 + a13 * b33;
+
+		te[ 1 ] = a21 * b11 + a22 * b21 + a23 * b31;
+		te[ 4 ] = a21 * b12 + a22 * b22 + a23 * b32;
+		te[ 7 ] = a21 * b13 + a22 * b23 + a23 * b33;
+
+		te[ 2 ] = a31 * b11 + a32 * b21 + a33 * b31;
+		te[ 5 ] = a31 * b12 + a32 * b22 + a33 * b32;
+		te[ 8 ] = a31 * b13 + a32 * b23 + a33 * b33;
+
+		return this;
+
+	},
+
+	multiplyToArray: function ( a, b, r ) {
+
+		var te = this.elements;
+
+		this.multiplyMatrices( a, b );
+
+		r[ 0 ] = te[ 0 ]; r[ 1 ] = te[ 1 ]; r[ 2 ] = te[ 2 ];
+		r[ 3 ] = te[ 3 ]; r[ 4 ] = te[ 4 ]; r[ 5 ] = te[ 5 ];
+		r[ 6 ] = te[ 6 ]; r[ 7 ] = te[ 7 ]; r[ 8 ] = te[ 8 ];
+
+		return this;
+
+	},
+
 	multiplyScalar: function ( s ) {
 
 		var te = this.elements;
@@ -231,6 +287,21 @@ Object.assign( Matrix3.prototype, {
 
 	},
 
+	equals: function ( matrix ) {
+
+		var te = this.elements;
+		var me = matrix.elements;
+
+		for ( var i = 0; i < 9; i ++ ) {
+
+			if ( te[ i ] !== me[ i ] ) return false;
+
+		}
+
+		return true;
+
+	},
+
 	fromArray: function ( array, offset ) {
 
 		if ( offset === undefined ) offset = 0;