SkyLightProbeDesc

The SkyLightProbeDesc class represents a dynamic sky light probe Descriptor that works in conjunction with atmospheric scattering simulation. It provides environment lighting that automatically updates based on the sun’s position, reproducing realistic sky lighting.

The sun direction is automatically calculated based on view.atmosphere.date, and lighting is updated every frame.

Related Documentation

For details on the atmosphere system, see the Atmosphere class.

Common Properties

visible

Type: boolean | undefined

Description: Controls the visibility of the object.

Default: true

Example:

{
  visible: false,
  skyLightProbe: { ... }
}

SkyLightProbe Properties

skyLightProbe

Type: object | undefined

Description: Configuration options for the sky light probe.

intensity

Type: number | undefined

Description: Specifies the intensity of the sky light probe. Higher values result in brighter light.

Default: 1

Example:

{
  skyLightProbe: {
    intensity: 1.0,
  }
}

Dynamic Updates

SkyLightProbeDesc automatically updates based on the following factors:

• Sun direction: Obtained from view.atmosphere.sunDirection
• Camera position: Considers differences in lighting inside and outside the atmosphere
• Atmosphere texture: Uses the irradiance texture

These updates are performed automatically every frame, so manual updating is unnecessary.

Updatable Properties

The only property that can be changed via the update() method after Descriptor creation is intensity. Properties such as sun direction and position are updated automatically and cannot be set manually.

Usage Examples

Basic Usage

import ThreeView from "@navaramap/three";
import { SkyLightProbeDesc } from "@navaramap/three_default_descs";
import { DefaultPlugin } from "@navaramap/three_default_plugin";

const view = new ThreeView();
const plugin = new DefaultPlugin();
view.addPlugin(plugin);
await view.init();

// Add default photorealistic objects
const defaultLayers = plugin.addDefaultPhotorealScene();

// The sky light probe automatically follows the sun's position
defaultLayers.skyLightProbe.update({
  skyLightProbe: {
    intensity: 1.0
  }
});

Changing Intensity for Day and Night

const skyLightProbe = view.addLight<SkyLightProbeDesc>({
  skyLightProbe: {
    intensity: 1.0
  }
});

// Set different intensities for day and night
const params = {
  dayIntensity: 1.0,
  nightIntensity: 5.0
};

view.atmosphere.on("sunChanged", () => {
  const isAtNight = view.atmosphere.isAtNight(view.camera.positionECEF);
  const intensity = isAtNight ? params.nightIntensity : params.dayIntensity;

  skyLightProbe.update({
    skyLightProbe: { intensity }
  });
});

Enable Only at Night

const skyLightProbe = view.addLight<SkyLightProbeDesc>({
  skyLightProbe: {
    intensity: 1.0
  },
});

// Increase intensity only at night
view.atmosphere.on("sunChanged", () => {
  const isAtNight = view.atmosphere.isAtNight(view.camera.positionECEF);
  if(!isAtNight) return;
  skyLightProbe.update({
    skyLightProbe: {
      intensity: 5.0
    },
  });
});

Integration with the Atmosphere System

SkyLightProbeDesc works closely with the atmospheric scattering simulation from the @takram/three-atmosphere package:

1. Irradiance texture retrieval: Obtains pre-computed irradiance textures from the atmosphere object
2. Sun direction synchronization: Synchronizes the sun direction every frame
3. Position update: Calculates appropriate lighting based on camera position

This enables natural environment lighting that responds to time of day and sun position.

Differences from LightProbeDesc

Feature	SkyLightProbeDesc	LightProbeDesc
Update method	Automatic (follows sun position)	Manual (fixed values)
Data source	Atmospheric simulation	Pre-computed coefficients
Use case	Dynamic sky lighting	Static environment lighting
Atmosphere	Required	Not required

Notes

• SkyLightProbeDesc requires the atmosphere object (Atmosphere) to function.
• Using plugin.addDefaultPhotorealScene() automatically includes SkyLightProbeDesc.
• Setting a higher intensity at night can achieve more natural nightscape lighting.
• It can be used in combination with other light Descriptors (AmbientLight, SunLight, etc.).