Pick Matrix2 from mrdoob#28923

Author: repalash

src/Three.js

@@ -122,6 +122,7 @@ export { Sphere } from './math/Sphere.js';
 export { Ray } from './math/Ray.js';
 export { Matrix4 } from './math/Matrix4.js';
 export { Matrix3 } from './math/Matrix3.js';
+export { Matrix2 } from './math/Matrix2.js';
 export { Box3 } from './math/Box3.js';
 export { Box2 } from './math/Box2.js';
 export { Line3 } from './math/Line3.js';

src/math/Matrix2.js

@@ -0,0 +1,54 @@
+export class Matrix2 {
+
+	constructor( n11, n12, n21, n22 ) {
+
+		Matrix2.prototype.isMatrix2 = true;
+
+		this.elements = [
+			1, 0,
+			0, 1,
+		];
+
+		if ( n11 !== undefined ) {
+
+			this.set( n11, n12, n21, n22 );
+
+		}
+
+	}
+
+	identity() {
+
+		this.set(
+			1, 0,
+			0, 1,
+		);
+
+		return this;
+
+	}
+
+	fromArray( array, offset = 0 ) {
+
+		for ( let i = 0; i < 4; i ++ ) {
+
+			this.elements[ i ] = array[ i + offset ];
+
+		}
+
+		return this;
+
+	}
+
+	set( n11, n12, n21, n22 ) {
+
+		const te = this.elements;
+
+		te[ 0 ] = n11; te[ 2 ] = n12;
+		te[ 1 ] = n21; te[ 3 ] = n22;
+
+		return this;
+
+	}
+
+}