132 lines
3.0 KiB
JavaScript
132 lines
3.0 KiB
JavaScript
import { Light } from './Light.js';
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import { PointLightShadow } from './PointLightShadow.js';
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/**
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* A light that gets emitted from a single point in all directions. A common
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* use case for this is to replicate the light emitted from a bare
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* lightbulb.
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*
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* This light can cast shadows - see the {@link PointLightShadow} for details.
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*
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* ```js
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* const light = new THREE.PointLight( 0xff0000, 1, 100 );
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* light.position.set( 50, 50, 50 );
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* scene.add( light );
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* ```
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*
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* @augments Light
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*/
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class PointLight extends Light {
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/**
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* Constructs a new point light.
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*
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* @param {(number|Color|string)} [color=0xffffff] - The light's color.
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* @param {number} [intensity=1] - The light's strength/intensity measured in candela (cd).
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* @param {number} [distance=0] - Maximum range of the light. `0` means no limit.
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* @param {number} [decay=2] - The amount the light dims along the distance of the light.
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*/
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constructor( color, intensity, distance = 0, decay = 2 ) {
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super( color, intensity );
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/**
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* This flag can be used for type testing.
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*
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* @type {boolean}
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* @readonly
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* @default true
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*/
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this.isPointLight = true;
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this.type = 'PointLight';
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/**
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* When distance is zero, light will attenuate according to inverse-square
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* law to infinite distance. When distance is non-zero, light will attenuate
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* according to inverse-square law until near the distance cutoff, where it
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* will then attenuate quickly and smoothly to 0. Inherently, cutoffs are not
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* physically correct.
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*
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* @type {number}
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* @default 0
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*/
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this.distance = distance;
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/**
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* The amount the light dims along the distance of the light. In context of
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* physically-correct rendering the default value should not be changed.
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*
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* @type {number}
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* @default 2
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*/
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this.decay = decay;
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/**
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* This property holds the light's shadow configuration.
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*
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* @type {PointLightShadow}
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*/
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this.shadow = new PointLightShadow();
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}
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/**
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* The light's power. Power is the luminous power of the light measured in lumens (lm).
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* Changing the power will also change the light's intensity.
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*
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* @type {number}
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*/
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get power() {
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// compute the light's luminous power (in lumens) from its intensity (in candela)
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// for an isotropic light source, luminous power (lm) = 4 π luminous intensity (cd)
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return this.intensity * 4 * Math.PI;
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}
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set power( power ) {
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// set the light's intensity (in candela) from the desired luminous power (in lumens)
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this.intensity = power / ( 4 * Math.PI );
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}
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dispose() {
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super.dispose();
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this.shadow.dispose();
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}
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copy( source, recursive ) {
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super.copy( source, recursive );
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this.distance = source.distance;
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this.decay = source.decay;
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this.shadow = source.shadow.clone();
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return this;
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}
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toJSON( meta ) {
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const data = super.toJSON( meta );
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data.object.distance = this.distance;
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data.object.decay = this.decay;
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data.object.shadow = this.shadow.toJSON();
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return data;
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}
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}
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export { PointLight };
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