aframe-laser-manipulation

laser-manipulation

Overview

A component to add to a controller that enables the user to move objects around using a laser pointer.

This extends the core laser-controls component, allowing objects that are pointed at to be manipulated in space, rather than just selected.

The basic control scheme is:

• Trigger to grab / release an entity
• While an entity is grabbed
  • Wherever the controller is moved / rotated, the entity moves as if it is "on a stick", the laser being the stick
  • Thumbstick forwards and backwards brings the entity away from / towards the controller.
  • Thumbstick left and right rotates the entity horizontally (yaw)
  • Grip + thumbstick forwards and backwards rotates the entity vertically (pitch)
• The axes used for rotation (pitch / yaw) are relative to the orientation of the controller. When the controller is held at an angle, the axes of rotation are adjusted to align with the controller.
• Note that "roll" can be achieved by rotating the controller. with a twist of the wrist.

Usage

This component does not implement all of the control scheme described above, but can be combined with the thumbstick-states component to deliver a full control scheme.

This example shows a configuration for the right controller that delivers the thumbstick controls described above.

<a-entity id="rhand"                  
          laser-controls="hand: right"
          raycaster="objects: [raycast-target]; far: Infinity; lineColor: red; lineOpacity: 0.5"
          laser-manipulation
          thumbstick-states__right="controller:#rhand;
                                    tBindings:moving-in,moving-out,rotating-y-plus,rotating-y-minus;
                                    tgBindings:rotating-x-plus,rotating-x-minus,rotating-y-plus,rotating-y-minus"
          oculus-touch-controls="hand: right">

Note that this component should also be deployed alongside laser-controls, raycaster and an appropriate tracked-controls component such as oculus-touch-controls.

States

The aspects of the control system driven by thumbsticks in the description above are implemented within this component as a set of A-Frame states, which drive movement as follows:

State	Effect
moving-in	Move the entity towards the controller
moving-out	Move the entity away from the controller
rotating-y-plus	Rotate the entity about the controller's y axis (yaw)
rotating-y-minus	Rotate the entity about the controller's y axis (yaw)
rotating-x-plus	Rotate the entity about the controller's x axis (pitch)
rotating-x-minus	Rotate the entity about the controller's x axis (pitch)

The configuration shown above for the thumbstick-states component will give the basic control scheme described at the top of this page.

However, any mechanism that sets and clears states on an A-Frame entity could be used to drive these controls.

Schema

Apart from the ability to customize thumbstick controls described above, there are limited configuration options for these controls. These may be extended in future.

Property	Description	Default
rotateRate	The rate of rotation of the entity (in degrees / second) when it is being rotated.	45
center	The center of rotation used when rotating the entity. This can be the center of the entity, or the point of contact of the raycaster with the entity. One of: center, contact.	center
grabEvents	Whether to generate events when an entity is grabbed / released	false
grabEvent	If grabEvents is true, the name of the event to generate when an entity is grabbed	mouseGrab
releaseEvent	If grabEvents is true, the name of the event to generate when an entity is released	mouseRelease
controlMethod	Either 'parent' or 'transform'. 'parent' mode re-parents the object to become a descendant of the controller. This is a simpler method, and may be more performant and stable. However re-parenting can cause issues if code in other components makes assumptions about objects' positions in the THREE.js scene graph. 'transform' mode leaves the object in the same position in the THREE.js scene graph, and instead adjusts its transform every tick as required.	parent
debug	Shows the position & orientation of the contact point. Also shows rotation axes when rotating about X & Y axes.	false

Installation

Via CDN

<script src="https://cdn.jsdelivr.net/npm/aframe-laser-manipulation@0.3.0/dist/laser-manipulation.min.js"></script>

Or via npm

npm install aframe-laser-manipulation

Examples

See object-manipulation.html for an example of how this can be used.

This example also uses desktop-vr-controller, so you can test out operations of a VR controller in a desktop (non-VR) environment.

Proxy Raycasting

laser-manipulation supports proxy raycasting via the raycast-target component

Code

laser-manipulation