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In order to use these random values you only have to group the objects, meant to be scattered, under the fluid container. Then adjust, e.g. "Rotation Random" and "Scale Random", and RealFlow | Cinema 4D will do the rest. If there is more than one scatter object grouped under the fluid container, the probability for an object to appear is always the same: with two objects, the probability for each object is 50%, with four objects it is 25%, with 10 objects it is 10%, for example.
Scattered stones and rocks (ground collision geometry is invisible here).
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