VRUNIVERSE - VRML Tutorials

Come closer ...

tested with

Today's topic is the ProximitySensor. This sensor is triggered whenever the user enters or leaves the space described by the sensor. Important fields are center and size which define the origin (center) and the extent of the ProximitySensor. Let's take our Hello World file from the first tutorial and see how we can modify it for today's topic.
Add a ProximitySensor as a child to the sphere node of the 'Hello World' example:


DEF sphere Transform {

  translation 0 0 0

  children [

    Shape { ... }

    DEF comeCloser ProximitySensor {

      center 0 0 0

      size 4 4 4

    }

  ]

}

Here we define a box centered at the origin with side lenghts of 4 units. this is about twice the size of the sphere. When a user walks or flies into the sphere this sensor triggers an eventOut 'isActive' which can be used to ROUTE it to a Script. I will use the 'touchBoxIsActive' script of the touch me example and rename it to 'comeCloserScript':

DEF comeCloserScript Script {

	eventIn SFBool enterProximitySensorIsActive

	eventOut SFBool bindView2

	

	url "javascript:

		function enterProximitySensorIsActive(active) {

			bindView2 = TRUE;

		}"

}

Again we ROUTE the eventOut 'isActive' from the ProximitySensor to the eventIn 'enterProximitySensorIsActive' of the Script 'comeCloserScript'. Upon triggering the Script we are able to Route the eventOut of the Script 'comeCloserScript' to the eventIn 'set_bind' of 'view2':


ROUTE comeCloser.isActive TO comeCloserScript.enterProximitySensorIsActive

ROUTE comeCloserScript.bindView2 TO view2.set_bind

Please take a look at the final Come closer source, then load Come closer.wrl and move towards the sphere. Right before you reach it you will be thrown back to the second Viewpoint 'view2'. Play around with the size of the ProximitySensor, e.g. make the sphere approachable from one side but not from the other:


DEF comeCloser ProximitySensor {

  center 2 0 0

  size 4 4 4

}

This moves the 'proximity box' two units to the right which lets you come close from the left but not from the right.
A ProximitySensor can be used to track a user's movements like entering rooms, vehicles etc. You would set up a 'proximity' box whereever you expect the user to go through and trigger events. The ProximitySensor can also detect when a user leaves it's sensor space.