Temporarily add Matrix2

src/three/Threejs.ts

 export {Ray} from 'three'
 export {Matrix4} from 'three'
 export {Matrix3} from 'three'
+export {Matrix2} from './math/Matrix2'
 export {Box3} from 'three'
 export {Box2} from 'three'
 export {Line3} from 'three'
 export {OrbitControls} from 'three/examples/jsm/controls/OrbitControls.js'
 export * from 'three/examples/jsm/utils/BufferGeometryUtils.js'
 export type {Event, EventListener, EventListener2} from 'three'
-export type {MeshPhysicalMaterialParameters, MeshBasicMaterialParameters, MaterialParameters} from 'three'
+export type {MeshPhysicalMaterialParameters, MeshBasicMaterialParameters, MaterialParameters} from 'three'

src/three/math/Matrix2.d.ts

+/* eslint-disable */
+export type Matrix2Tuple = [
+    n11: number,
+    n12: number,
+    n21: number,
+    n22: number,
+];
+
+/**
+ * A class representing a 2x2 {@link https://en.wikipedia.org/wiki/Matrix_(mathematics) matrix}.
+ *
+ * @example
+ * const m = new Matrix2();
+ */
+export class Matrix2 {
+    readonly isMatrix2: true;
+
+    /**
+     * A {@link https://en.wikipedia.org/wiki/Row-_and_column-major_order column-major} list of matrix values.
+     */
+    elements: Matrix2Tuple;
+
+    /**
+     * Creates a 2x2 {@link https://en.wikipedia.org/wiki/Identity_matrix identity matrix}.
+     */
+    constructor();
+
+    /**
+     * Creates a 2x2 matrix with the given arguments in row-major order.
+     */
+    constructor(n11: number, n12: number, n21: number, n22: number);
+
+    /**
+     * Resets this matrix to the 2x2 identity matrix:
+     */
+    identity(): this;
+
+    /**
+     * Sets the elements of this matrix based on an array in
+     * {@link https://en.wikipedia.org/wiki/Row-_and_column-major_order#Column-major_order column-major} format.
+     *
+     * @param array the array to read the elements from
+     * @param offset (optional) index of first element in the array. Default is `0`.
+     */
+    fromArray(array: ArrayLike<number>, offset?: number): this;
+
+    /**
+     * Sets the 2x2 matrix values to the given
+     * {@link https://en.wikipedia.org/wiki/Row-_and_column-major_order row-major} sequence of values:
+     * [n11, n12,
+     *  n21, n22]
+     */
+    set(n11: number, n12: number, n21: number, n22: number): this;
+}

src/three/math/Matrix2.js

+/* eslint-disable */
+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
+
+    }
+
+}