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When you take a look at the emitter's “Particles” panel you will see that it lacks a “Resolution” parameter, because “Emission rate” is used to create particles. The value you enter here is the number of particles which are created per second per cubic metre.
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Angle threshold
This parameter takes the fluid surface's main direction of motion into account. The particles themselves also have an individual direction of motion caused by their velocity. RealFlow measures the angle between these two directions, and when the angle is between 0° and the given threshold splash particles will be added. The value is measured in degrees [deg].
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