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The fluid's height is evaluated at each vertex of the mesh and, of course, this process returns a very broad range of values. These ranges are difficult to handle, because you have to know the exact minimum and maximum values. Therefore they are normalized, and after this process, all values will range between 0 and 1.
With “@ height min” and “@ height max” it is possible to attenuate (attenuation can be seen as a damping effect) the waves' height for each vertex in the given range. If you use a value of 0.2 for “@ height min” and 0.7 for “@ height max”, for example, only vertices within this range will be affected. This way it is possible to fine-tune the height of the displacement waves exactly to your needs.
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