Function mapOpacityTides

mapOpacityTides(json?): void
Set the tide and current layer opacity.

Setting this value to zero hides the tides and currents layer. Setting this value to one shows the layer at full opacity.
Parameters
- json: {
  opacity: number;
  } = ...
  - opacity: number
    number: 0 to 1
Returns void
Example
```
{opacity: 0.6}
```