This new property allows you to fine-tune the look of water reflections. 0 = no reflections, 1 = full reflections.
Animating WaterReflectance with default WaterTransparency:
Animating WaterReflectance with WaterTransparency=1:
Enjoy.
P.S. This is currently available on PC/Mac and will roll out to Xbox and mobile over the next week or two. The update is purely visual and does not affect gameplay so you probably should not be too concerned about other platforms not getting the update but if you are - wait for the update to be released on mobile/console before using it in your games.
I can only imagine the cool (under?)water games/showcases that will start to be made. This and the other water properties were great additions. (Game is “Underwater World”)