Example: Label appering on the given distance from object to camera

[NataliaDSmirnova]

The example shows a way to add custom labels. It presents how distance from camera to threebox object can be calculated using threejs math.

Note: distance is in world units (not meters).

Additional elements:

• threejs stats measuring performance
• threejs GUI control changing distance threshold
• element showing the current distance from the camera to the red cube

Main functions:

• createLabel()
• updateLabel()

The example is a result of a conversation here: #409

[NataliaDSmirnova]

@jscastro76, could you add any comments? I'd be grateful 😊