# fsMapViewSetMapIsolinesVisibility<no value>
This function can be used to show or hide isolines on the MapView.

 

 

##### Syntax

``` wasm
bool fsMapViewSetMapIsolinesVisibility(
    FsContext ctx,
    FsTextureId id,
    bool bVisibility
    )
```

 

##### Members

{{< table-wrapper >}}

| Parameters    | Description                                                                |
|---------------|----------------------------------------------------------------------------|
| `ctx`         | A value of type `FsContext` provided as an argument of the gauge callback. |
| `id`          | The MapView render ID as returned by the function `fsMapViewCreate`.       |
| `bVisibility` | Set to true to make the isolines visible, set to false to make invisible.  |

{{< /table-wrapper >}}


 

##### Return Values

Returns false if:

-   no texture matches the given MapView ID
-   the `ctx` is invalid

Otherwise it will return true.

 

 

##### Remarks

Isolines are only visible when in the altitude view (see [here](fsmapviewsetviewmode/) for details):

{{< image-center
    src="images/6_Programming/WASM/map_view_2_isolines.png"
    alt="Example Of Isolines Drawn In The Map View" >}}