object.isSensor

Type Boolean
Object Body
Library physics.*
Revision Current Public Release (2017.3068)
Keywords body, isSensor

Overview

A sensor is a fixture that detects collisions but does not produce a physical response. Sensors do not generate contact points.

The isSensor property is a set-only boolean value that, if set to true, prevents any visible collisions from happening to the object, although "began" and "ended" collision events are still fired.

Gotchas

One-Sided Platforms

For one-sided platforms that a jumping character can pass through from below but should land upon from above, the isSensor property may not be sufficient to handle all cases. Instead, consider the isEnabled property of the PhysicsContact object.

Fixtures

In Box2D, isSensor is a property for a specific fixture or, in Corona terms, a "body element" — it is not a property of the entire body. However, Corona does not currently expose access to individual body elements after the body is created, so it's not possible to set properties on individual body elements following creation of the body. Consequently, setting isSensor = true on a body sets this behavior for the entire body. One implication of this pertains to complex physics bodies where some elements are sensors and some are not — in this case, the isSensor property will permanently override the individual body element settings.

Example

local laserBeam = display.newImage( "laserBeam.png" )
physics.addBody( laserBeam, "dynamic" )
laserBeam.gravityScale = 0

-- Make the object a "bullet" type object
laserBeam.isBullet = true

-- Make the object a sensor
laserBeam.isSensor = true

laserBeam:setLinearVelocity( 400, 0 )