0, 20, -20),
			new t3d.Vector3(-20, 20, 20)
		];

		for (let i = 0; i < 3; i++) {
			const cube_geometry = new t3d.BoxGeometry(3, 40, 3);
			const lambert = new t3d.LambertMaterial();
			lambert.diffuse.setHex(0xffffff);
			const cube = new t3d.Mesh(cube_geometry, lambert);
			cube.position.copy(positions[i]);
			cube.castShadow = true;
			cube.receiveShadow = true;
			scene.add(cube);
			cubes.push(cube);
		}

		const plane_geometry = new t3d.PlaneGeometry(2000, 2000);
		const lambert = new t3d.LambertMat