定義 base，縮放時維持原固定大小

 //第一種做法

//固定14f與1000公尺，照zoom level 變化
val baseZoomLevel = 14f
val baseRadiusMeters = 1000.0

val dynamicRadius by remember {
    derivedStateOf {
        val currentZoom = cameraPositionState.position.zoom
        val scale = 2.0.pow((baseZoomLevel - currentZoom).toDouble())
        baseRadiusMeters * scale
    }
}