Method rotate

packages/melonjs/src/math/matrix3d.ts:674–735

* rotate this matrix (counter-clockwise) by the specified angle (in radians). * @param angle - Rotation angle in radians. * @param [v] - the axis to rotate around (defaults to Z axis) * @returns Reference to this object for method chaining

(angle: number, v?: Vector3d)

	 * @returns Reference to this object for method chaining
	 */
	rotate(angle: number, v?: Vector3d) {
		if (angle !== 0) {
			const a = this.val;
			let x = v ? v.x : 0;
			let y = v ? v.y : 0;
			let z = v ? v.z : 1;

			let len = Math.sqrt(x * x + y * y + z * z);

			if (len < EPSILON) {
				return this;
			}

			len = 1 / len;
			x *= len;
			y *= len;
			z *= len;

			const s = Math.sin(angle);
			const c = Math.cos(angle);
			const t = 1 - c;

			const a00 = a[0];
			const a01 = a[1];
			const a02 = a[2];
			const a03 = a[3];
			const a10 = a[4];
			const a11 = a[5];
			const a12 = a[6];
			const a13 = a[7];
			const a20 = a[8];
			const a21 = a[9];
			const a22 = a[10];
			const a23 = a[11];

			// Construct the elements of the rotation matrix
			const b00 = x * x * t + c;
			const b01 = y * x * t + z * s;
			const b02 = z * x * t - y * s;
			const b10 = x * y * t - z * s;
			const b11 = y * y * t + c;
			const b12 = z * y * t + x * s;
			const b20 = x * z * t + y * s;
			const b21 = y * z * t - x * s;
			const b22 = z * z * t + c;

			// Perform rotation-specific matrix multiplication
			a[0] = a00 * b00 + a10 * b01 + a20 * b02;
			a[1] = a01 * b00 + a11 * b01 + a21 * b02;
			a[2] = a02 * b00 + a12 * b01 + a22 * b02;
			a[3] = a03 * b00 + a13 * b01 + a23 * b02;
			a[4] = a00 * b10 + a10 * b11 + a20 * b12;
			a[5] = a01 * b10 + a11 * b11 + a21 * b12;
			a[6] = a02 * b10 + a12 * b11 + a22 * b12;
			a[7] = a03 * b10 + a13 * b11 + a23 * b12;
			a[8] = a00 * b20 + a10 * b21 + a20 * b22;
			a[9] = a01 * b20 + a11 * b21 + a21 * b22;
			a[10] = a02 * b20 + a12 * b21 + a22 * b22;