three/src/helpers/PlaneHelper.js

import { Line } from '../objects/Line.js';
import { Mesh } from '../objects/Mesh.js';
import { LineBasicMaterial } from '../materials/LineBasicMaterial.js';
import { MeshBasicMaterial } from '../materials/MeshBasicMaterial.js';
import { Float32BufferAttribute } from '../core/BufferAttribute.js';
import { BufferGeometry } from '../core/BufferGeometry.js';
import { FrontSide, BackSide } from '../constants.js';

class PlaneHelper extends Line {

	constructor( plane, size = 1, hex = 0xffff00 ) {

		const color = hex;

		const positions = [ 1, - 1, 1, - 1, 1, 1, - 1, - 1, 1, 1, 1, 1, - 1, 1, 1, - 1, - 1, 1, 1, - 1, 1, 1, 1, 1, 0, 0, 1, 0, 0, 0 ];

		const geometry = new BufferGeometry();
		geometry.setAttribute( 'position', new Float32BufferAttribute( positions, 3 ) );
		geometry.computeBoundingSphere();

		super( geometry, new LineBasicMaterial( { color: color, toneMapped: false } ) );

		this.type = 'PlaneHelper';

		this.plane = plane;

		this.size = size;

		const positions2 = [ 1, 1, 1, - 1, 1, 1, - 1, - 1, 1, 1, 1, 1, - 1, - 1, 1, 1, - 1, 1 ];

		const geometry2 = new BufferGeometry();
		geometry2.setAttribute( 'position', new Float32BufferAttribute( positions2, 3 ) );
		geometry2.computeBoundingSphere();

		this.add( new Mesh( geometry2, new MeshBasicMaterial( { color: color, opacity: 0.2, transparent: true, depthWrite: false, toneMapped: false } ) ) );

	}

	updateMatrixWorld( force ) {

		let scale = - this.plane.constant;

		if ( Math.abs( scale ) < 1e-8 ) scale = 1e-8; // sign does not matter

		this.scale.set( 0.5 * this.size, 0.5 * this.size, scale );

		this.children[ 0 ].material.side = ( scale < 0 ) ? BackSide : FrontSide; // renderer flips side when determinant < 0; flipping not wanted here

		this.lookAt( this.plane.normal );

		super.updateMatrixWorld( force );

	}

}

export { PlaneHelper };