distanceFromCamera.kt

    private fun measureDistanceFromCamera(){
        val frame = arFragment!!.arSceneView.arFrame
        if (placedAnchorNodes.size >= 1) {
            val distanceMeter = calculateDistance(
                placedAnchorNodes[0].worldPosition,
                frame!!.camera.pose)
            measureDistanceOf2Points(distanceMeter)
        }
    }

    private fun measureDistanceOf2Points(distanceMeter: Float){
        val distanceTextCM = makeDistanceTextWithCM(distanceMeter)
        val textView = (distanceCardViewRenderable!!.view as LinearLayout)
            .findViewById<TextView>(R.id.distanceCard)
        textView.text = distanceTextCM
        Log.d(TAG, "distance: ${distanceTextCM}")
    }

private fun calculateDistance(x: Float, y: Float, z: Float): Float{
        return sqrt(x.pow(2) + y.pow(2) + z.pow(2))
    }

    private fun calculateDistance(objectPose0: Vector3, objectPose1: Pose): Float{
        return calculateDistance(
            objectPose0.x - objectPose1.tx(),
            objectPose0.y - objectPose1.ty(),
            objectPose0.z - objectPose1.tz()
        )
    }

    private fun changeUnit(distanceMeter: Float, unit: String): Float{
        return when(unit){
            "cm" -> distanceMeter * 100
            "mm" -> distanceMeter * 1000
            else -> distanceMeter
        }
    }