three.js/src/extras/helpers/RectAreaLightHelper.js

/**
 * @author abelnation / http://github.com/abelnation
 */

import { Object3D } from '../../core/Object3D';
import { Vector3 } from '../../math/Vector3';
import { Shape } from '../../extras/core/Shape';
import { Mesh } from '../../objects/Mesh';
import { MeshBasicMaterial } from '../../materials/MeshBasicMaterial';
import { ShapeBufferGeometry } from '../../geometries/ShapeBufferGeometry';

function RectAreaLightHelper( light ) {

    Object3D.call( this );

    this.light = light;
    this.light.updateMatrixWorld();

    this.lightMat = new MeshBasicMaterial( {
        color: light.color,
        fog: false
    } );

    this.lightWireMat = new MeshBasicMaterial( {
        color: light.color,
        fog: false,
        wireframe: true
    } );

    var hx = this.light.width / 2.0;
    var hy = this.light.height / 2.0;

    this.lightShape = new ShapeBufferGeometry( new Shape( [
        new Vector3( - hx,   hy, 0 ),
        new Vector3(   hx,   hy, 0 ),
        new Vector3(   hx, - hy, 0 ),
        new Vector3( - hx, - hy, 0 )
    ] ) );

    // shows the "front" of the light, e.g. where light comes from

    this.lightMesh = new Mesh( this.lightShape, this.lightMat );

    // shows the "back" of the light, which does not emit light

    this.lightWireMesh = new Mesh( this.lightShape, this.lightWireMat );

    this.add( this.lightMesh );
    this.add( this.lightWireMesh );

    this.update();

}

RectAreaLightHelper.prototype = Object.create( Object3D.prototype );
RectAreaLightHelper.prototype.constructor = RectAreaLightHelper;

RectAreaLightHelper.prototype.dispose = function () {

    this.lightMesh.geometry.dispose();
    this.lightMesh.material.dispose();
    this.lightWireMesh.geometry.dispose();
    this.lightWireMesh.material.dispose();

};

RectAreaLightHelper.prototype.update = function () {

    var vector = new Vector3();
    var vector2 = new Vector3();

    // TODO (abelnation) why not just make light helpers a child of the light object?
    if ( this.light.target ) {

        vector.setFromMatrixPosition( this.light.matrixWorld );
        vector2.setFromMatrixPosition( this.light.target.matrixWorld );

        var lookVec = vector2.clone().sub( vector );
        this.lightMesh.lookAt( lookVec );
        this.lightWireMesh.lookAt( lookVec );

    }

    this.lightMesh.material.color.copy( this.light.color ).multiplyScalar( this.light.intensity );
    this.lightWireMesh.material.color.copy( this.light.color ).multiplyScalar( this.light.intensity );

    var oldShape = this.lightShape;

    var hx = this.light.width / 2.0;
    var hy = this.light.height / 2.0;

		this.lightShape = new ShapeBufferGeometry( new Shape( [
				new Vector3( - hx,   hy, 0 ),
				new Vector3(   hx,   hy, 0 ),
				new Vector3(   hx, - hy, 0 ),
				new Vector3( - hx, - hy, 0 )
		] ) );

    this.lightMesh.geometry = this.lightShape;
    this.lightWireMesh.geometry = this.lightShape;

    oldShape.dispose();

};

export { RectAreaLightHelper };