light

The light component defines the entity as a source of light. Light affects all materials that have not specified a flat shading model with shader: flat. Note that lights are computationally expensive we should limit number of lights in a scene.

<a-entity light="color: #AFA; intensity: 1.5" position="-1 1 0"></a-entity>

By default, A-Frame scenes inject default lighting, an ambient light and a directional light. These default lights are visible in the DOM with the data-aframe-default-light attribute. Whenever we add any lights, A-Frame removes the default lights from the scene.

<!-- Default lighting injected by A-Frame. -->
<a-entity light="type: ambient; color: #BBB"></a-entity>
<a-entity light="type: directional; color: #FFF; intensity: 0.6" position="-0.5 1 1"></a-entity>

To manually disable the defaults, without adding other lights:

<a-scene light="defaultLightsEnabled: false">
  <!-- ... -->
</a-scene>

Properties

All light types support a few basic properties:

Light Types

Different types of lights include unique properties. We will go through each type, including its properties and when it may be the right choice.

Ambient

Ambient lights globally affect all entities in the scene. The color and intensity properties define ambient lights. Additionally, position, rotation, and scale have no effect on ambient lights.

We recommend to have some form of ambient light such that shadowed areas are not fully black and to mimic indirect lighting.

<a-entity light="type: ambient; color: #CCC"></a-entity>

Directional

Directional lights are like a light source that is infinitely far away, but shining from a specific direction, like the sun. Thus, absolute position do not have an effect on the intensity of the light on an entity. We can specify the direction using the position component.

The example below creates a light source shining from the upper-left at a 45-degree angle. Note that because only the vector matters, position="-100 100 0" and position="-1 1 0" are the same.

<a-entity light="type: directional; color: #EEE; intensity: 0.5" position="-1 1 0"></a-entity>

We can specify the direction of the directional light with its orientation by creating a child entity it targets. For example, pointing down its -Z axis:

<a-light type="directional" position="0 0 0" rotation="-90 0 0" target="#directionaltarget">
  <a-entity id="directionaltarget" position="0 0 -1"></a-entity>
</a-light>

Directional lights are the most efficient type for adding realtime shadows to a scene. You can use shadows like so:

<a-light type="directional" light="castShadow:true;" position="1 1 1" intensity="0.5" shadow-camera-automatic="#objects"></a-light>

The shadow-camera-automatic configuration maps to light.shadowCameraAutomatic which tells the light to automatically update the shadow camera to be the minimum size and position to encompass the target elements.

Hemisphere

Hemisphere lights are like an ambient light, but with two different colors, one from above (color) and one from below (groundColor). This can be useful for scenes with two distinct lighting colors (e.g., a grassy field under a gray sky).

<a-entity light="type: hemisphere; color: #33C; groundColor: #3C3; intensity: 2"></a-entity>

Point

Point lights, unlike directional lights, are omni-directional and affect materials depending on their position and distance. Point lights are like light bulb. The closer the light bulb gets to an object, the greater the object is lit.

<a-entity light="type: point; intensity: 0.75; distance: 50; decay: 2"
          position="0 10 10"></a-entity>

Spot

Spot lights are like point lights in the sense that they affect materials depending on its position and distance, but spot lights are not omni-directional. They mainly cast light in one direction, like the Bat-Signal.

<a-entity light="type: spot; angle: 45"></a-entity>

Probe

Probe lights are kind of like ambient lighting in that they don't have a particular source or direction and light everything equally.

Where they differ though is that they will color each angle differently based upon a spherical harmonic. This spherical harmonic is generated by analyzing a cubemap. The cubemap you provide doesn't need to be high resolution since it's only used to generate the spherical harmonics.

Example:

<a-assets>
  <a-cubemap id="pisa">
  
  
  
  
  
  
  </a-cubemap>
</a-assets>

<a-light type="probe" envMap="#pisa"></a-light>

Configuring Shadows

A-Frame includes support for realtime shadow rendering. With proper configuration, objects (both moving or stationary) will cast shadows adding depth and realism to a scene. Since shadows come with many properties, it is very helpful to use the A-Frame Inspector to configure shadows

Light types that support shadows (point, spot, and directional) include additional properties:

Adding Real-Time Shadows

NOTE: Real-time shadows add performance overhead. When objects in a scene are stationary, or especially when optimizing for mobile devices, be aware of other techniques for realistic shadows, such as baking light and shadow information into a texture before importing assets into A-Frame.

• 1. Create at least one light with castShadow: true. Three light types support shadows (point, spot, and directional). Of the three, directional lights will have the best performance. Combining an ambient light (without shadows) and a directional light (with shadows) is a good place to start.

<a-scene>
  <a-entity light="type: ambient; intensity: 0.5;"></a-entity>
  <a-entity light="type: directional;
                   castShadow: true;
                   intensity: 0.4;
                   shadowCameraVisible: true;"
            position="-5 3 1.5"></a-entity>
</a-scene>

In the example above, the directional light has lower intensity than the ambient light, for slightly softer shadows. Adding shadowCameraVisible: true creates a visual aid for debugging: objects outside the camera's view cannot cast or receive shadows.

• 2. Add the shadow component to objects in the scene that should cast or receive shadows.

<a-gltf-model src="tree.gltf" shadow="cast: true"></a-gltf-model>
<a-circle id="ground" radius="10" rotation="-90 0 0" shadow="receive: true"></a-circle>

• 3. Adjust the shadow camera position and frustum (shadowCameraTop, shadowCameraRight, ...) of the directional light, until it envelops the scene tightly. If the frustum is too small, shadows will be missing or partially clipped. If the frustum is too large, shadows will appear coarse or pixelated. The size of the shadow map (shadowMapHeight: 512, shadowMapWidth: 512) determines the resolution at which shadows are computed, so tightly sizing the shadow camera around your scene will make the best use of this resolution and device performance.

• 4. Refine shadow appearance. Scene-wide options, affecting all lights, may be configured on the scene's shadow system.

Shadow System Properties

These global options affect the entire scene, and are set using the shadow system on the <a-scene> root element.

<a-scene shadow="type: pcfsoft">
  <!-- ... -->
</a-scene>