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Unreal Water System - meaning of all those parameters

Trying to get into the new cool water system in 4.26, watching a lot of tutorials and trying my own first experiments, I thought, that it might be valuable to have some explanation on the available parameters. I like to have overview graphics, which explain things on a single quick view, so here’s my very first attempt for such an overview image, covering stuff I learnt from several sources, e.g. Blurring vs. Smooth Blending…

Might be a better way to do it, but it’s at least helpful for me and I hope, someone else can use this as well. I also hope to improve that and include stuff like terracing, displacement and many other parameters, I do not yet understand. Would be great, if this could be some base for discussion and exchange of experiences about the different parameters found in the system.

Trying to understand the z-offset parameter, having the following test landscape:


Now changing transform location and ZOffset values to see, what makes the difference. The result is

  • Rising the transform location elevates the terrain AND the water surface
  • Rising the ZOffset value only elevates the landscape, but keeps watersurface at its original height.

All in all it is really somewhat tricky to work with water. If you have existing terrain, one would expect to be able just to put in some water filling holes, but whatever you do, an already sculpted terrain will be completely ‘destroyed’ by the waterbody actors. The “Affects Landscape” checkbox does not help here from what I found.

The only way, I got it working is to create flat landscape, place all water bodies at their places, elevate them to the desired height, tune some of the parameters to make terrain look a little bit like it should do in the end. Then create a new Layer in landscape and sculpt the landscape. Water bodies now work really smooth.

From now on, do not touch any parameters of the water bodies any more, as this will again completely make the sculpts useless. Maybe I have a complete misunderstanding of what’s going on, but I’m not the only one facing this issue. See https://forums.unrealengine.com/development-discussion/content-creation/1840092-new-4-26-water-questions

Yeah it’s tricky, one has to keep in mind that all of these are stacking heightmaps, and the min/max/additive/blend controls how to they mix, also the alphas on the actual layers. For instance if you have a top most layer (above the water layer) with alpha layer 1.0, then it will “block” water in some cases, while, like 0.5 will let it through

AFAIK, to have lakes etc work properly you need to have that heightmap in your water landscape layer, and within the ocean spline, lakes will work relative to that.

If you want shores etc that are not capped by the ocean you can but them in a top layer, just make sure you’ve scaled it’s height if you import a height map, it’s very tricky to make lakes work on that layer however.

Seems like a best solution would be to split imported heightmaps into one shore aspect that lives in a separate layer, and everything on the ocean landmass into another that you put on the water layer, then you dont have to fiddle with your spline and lakes work. Getting that setup isn’t exactly the easiest tho so I hope there’s some better work flow.

I also don’t know how you affect terrain on island and still are able to use lakes etc, you cant really but height in the water layer, and if you put it somewhere else the lakes won’t react correctly, maybe there some way to link terrain layers to an actor? Would be great if you could have a layer just going on top an island

Thanks, Homde, for your reply. Yes, this Blend Mode and Alpha something important, that I did not take into consideration yet. Now playing with this and testing behaviour. I do not yet fully understand the different modes, as they behave somewhat strange. For example from the description for Additive “Useful when you want to preserve underlying detail or ramps” - but additive does change my underlying details. On the other hand, I managed to add a mountain lake using the “Min” mode. Currently its more or less trial and error to get some resuls, but I’ll continue to experiment.

After playing with the water system, getting results but still not understanding how to get desired results without more or less playing around and doing try and error, I decided to have a look at the Landmass Plugin without any water at all. This might be a good way to understand what’s going on. Just placing a CustomBrushLandmass into my scene was quite useful. A whole bunch of all those settings like falloffs are pure landmass settings and are not really new with water. So learning Landmass first, then going for water is what I want to do now.