three
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JavaScript 3D library
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JavaScript
import { Light } from './Light.js';
import { PointLightShadow } from './PointLightShadow.js';
/**
* A light that gets emitted from a single point in all directions. A common
* use case for this is to replicate the light emitted from a bare
* lightbulb.
*
* This light can cast shadows - see the {@link PointLightShadow} for details.
*
* ```js
* const light = new THREE.PointLight( 0xff0000, 1, 100 );
* light.position.set( 50, 50, 50 );
* scene.add( light );
* ```
*
* @augments Light
*/
class PointLight extends Light {
/**
* Constructs a new point light.
*
* @param {(number|Color|string)} [color=0xffffff] - The light's color.
* @param {number} [intensity=1] - The light's strength/intensity measured in candela (cd).
* @param {number} [distance=0] - Maximum range of the light. `0` means no limit.
* @param {number} [decay=2] - The amount the light dims along the distance of the light.
*/
constructor( color, intensity, distance = 0, decay = 2 ) {
super( color, intensity );
/**
* This flag can be used for type testing.
*
* @type {boolean}
* @readonly
* @default true
*/
this.isPointLight = true;
this.type = 'PointLight';
/**
* When distance is zero, light will attenuate according to inverse-square
* law to infinite distance. When distance is non-zero, light will attenuate
* according to inverse-square law until near the distance cutoff, where it
* will then attenuate quickly and smoothly to 0. Inherently, cutoffs are not
* physically correct.
*
* @type {number}
* @default 0
*/
this.distance = distance;
/**
* The amount the light dims along the distance of the light. In context of
* physically-correct rendering the default value should not be changed.
*
* @type {number}
* @default 2
*/
this.decay = decay;
/**
* This property holds the light's shadow configuration.
*
* @type {PointLightShadow}
*/
this.shadow = new PointLightShadow();
}
/**
* The light's power. Power is the luminous power of the light measured in lumens (lm).
* Changing the power will also change the light's intensity.
*
* @type {number}
*/
get power() {
// compute the light's luminous power (in lumens) from its intensity (in candela)
// for an isotropic light source, luminous power (lm) = 4 π luminous intensity (cd)
return this.intensity * 4 * Math.PI;
}
set power( power ) {
// set the light's intensity (in candela) from the desired luminous power (in lumens)
this.intensity = power / ( 4 * Math.PI );
}
dispose() {
this.shadow.dispose();
}
copy( source, recursive ) {
super.copy( source, recursive );
this.distance = source.distance;
this.decay = source.decay;
this.shadow = source.shadow.clone();
return this;
}
}
export { PointLight };