camera

Note: This documentation is for the old 1.4.0 version of A-Frame. Check out the documentation for the current 1.6.0 version

The camera component defines from which perspective the user views the scene. The camera is commonly paired with controls components that allow input devices to move and rotate the camera.

Examples

A camera should usually be positioned at the average height of human eye level (1.6 meters). When used with controls that receive rotation or position (e.g. from a VR device) this position will be overridden.

<a-entity camera look-controls position="0 1.6 0"></a-entity>

When moving or rotating the camera relative to the scene, use a camera rig. By doing so, the camera’s height offset can be updated by roomscale devices, while still allowing the tracked area to be moved independently around the scene.

<a-entity id="rig" position="25 10 0">
  <a-entity id="camera" camera look-controls></a-entity>
</a-entity>

Properties

Default Camera

If a camera is not specified, A-Frame will inject a default camera:

<a-entity camera="active: true" look-controls wasd-controls position="0 1.6 0" data-aframe-default-camera></a-entity>

If a camera is specified (e.g., our own <a-camera> or <a-entity camera>), then the default camera will not be added.

VR Behavior

When exiting VR, the camera will restore its rotation to its rotation before it entered VR. This is so when we exit VR, the rotation of the camera is back to normal for a desktop screen.

Far, near, fov, zoom properties only apply in 2D and magic window modes. In VR mode the camera parameters are supplied by the WebVR / WebXR API to match IPD and headset FOV. Those aren’t configurable.

Changing the Active Camera

When the active property gets toggled, the component will notify the camera system to change the current camera used by the renderer:

var secondCameraEl = document.querySelector('#second-camera');
secondCameraEl.setAttribute('camera', 'active', true);

Fixing Entities to the Camera

To fix entities onto the camera such that they stay within view no matter where the user looks, you can attach those entities as a child of the camera. Use cases might be a heads-up display (HUD).

<a-entity camera look-controls>
  <a-entity geometry="primitive: plane; height: 0.2; width: 0.2" position="0 0 -1"
            material="color: gray; opacity: 0.5"></a-entity>
</a-entity>

Note that you should use HUDs sparingly as they cause irritation and eye strain in VR. Consider integrating menus into the fabric of the world itself. If you do create a HUD, make sure that the HUD is more in the center of the field of view such that the user does not have to strain their eyes to read it.

Reading Position or Rotation of the Camera

To actively read the position or rotation of the camera, use a tick handler of a component that reads the position or rotation, and does something with it. Then attach the component to the camera.

AFRAME.registerComponent('rotation-reader', {
  tick: function () {
    // `this.el` is the element.
    // `object3D` is the three.js object.

    // `rotation` is a three.js Euler using radians. `quaternion` also available.
    console.log(this.el.object3D.rotation);

    // `position` is a three.js Vector3.
    console.log(this.el.object3D.position);
  }
});

// <a-entity camera look-controls rotation-reader>

Reading World Position or Rotation of the Camera

three.js has methods to attain position or rotation (or scale) in world space versus object local space.

AFRAME.registerComponent('rotation-reader', {
  /**
   * We use IIFE (immediately-invoked function expression) to only allocate one
   * vector or euler and not re-create on every tick to save memory.
   */
  tick: (function () {
    var position = new THREE.Vector3();
    var quaternion = new THREE.Quaternion();

    return function () {
      this.el.object3D.getWorldPosition(position);
      this.el.object3D.getWorldQuaternion(quaternion);
      // position and rotation now contain vector and quaternion in world space.
    };
  })()
});