WaterLevel is an operator used to create particles that can be mainly used by fluids. However, as it is with everything in thinkingParticles, you may use this operator in millions of other creative ways.

This operator basically lets you take any mesh and use it as a upper surface level placement for particles to be generated. Particles can be created in a ordered (raster) or random way. Multiple water level objects and ground objects can be used to generate a multi level particle filled volume.

On - (Bool) This input data stream determines whether the operator is considered 'on' or 'off.' You can connect other operators to this input channel such as a Bool Helper to activate/deactivate the whole operator.

Time - (Time) This input data stream is used to define the local time for the operator when the user wants to override the default system time.

All other operator input options represent the identical UI controls and are explained in detail in the below rollout menu section.

BirthParticle - (Particle) This output data stream sends particle data for newly created particles to other operators. Every particle birth will activate all rules connected to this particle data stream. As a result , this can be used to directly assign a value to the particle.

PCounter - (Integer) This output data stream provides a “counter-like” function that holds the current number of created particles at the given frame. This counter is reset per frame and starts over again at 0. As a result, you can use this output data when you want to trigger other rules based on the creation of a certain number of particles.

WaterLevel Objects - this list box shows the selected objects that will be used to define the upper “water” level of the particles.

Add - press this button to start a standard 3ds Max pick object operation

Remove - click this button to remove the selected object from the list

Object Axis - defines the primary axis to shoot rays towards the ground objects. By default the Object's Z-Axis is used. Available options are:

• Object X - when selected the objects X axis is used to define the ground direction.
• Object Y - when selected the objects Y axis is used to define the ground direction.
• Object Z - when selected the objects Z axis is used to define the ground direction.

Side - sets if the intersection test should work front only or back sided.

Mode - due to the fact that this is particle generator offers a true volumetric filling option which is based on a raster or grid, it is easy to create multiple millions of particles in a blink of an eye. To ensure there are no unwanted side effects there are two modes available:

Test (default) - when selected, no particles are created at all. However, the amount of particles that might be created will be displayed in the Count number field in the Show section of this rollout menu.

Generate - enable this option to actually create the particles and use them in your simulations.

Grid Size -sets the raster size of the particles in world units.

Variation - randomizes the particle position at creation time. A value of 0  will create particles positioned in a cell like raster, set this value to 1.0 to create maximum randomness within the particle grid.

Max Depth - sets the maximum depth at which particles should be created as seen from the top surface level.

MaxParticles - no more than this amount of particles will ever be created by this generator. Change this value to a reasonable amount for the intended purpose.

First Level Stop - this particle generator handles cavities and undercuts in a very efficient way. However sometimes it is not practicable or needed to have hollow or undercut areas filled with particles as well.

Ground Objects - this list box displays all selected ground objects.

Add - press this button to start a standard 3ds Max pick object operation

Remove - click this button to remove the selected object from the list

Side - sets if the intersection test for the ground object should work either front only,  back side or both.

Material ID - defines a specific material ID that will be used from the ground object to generate particles. This is especially useful for containers like curved double wall glasses.

Bias - defines an offset to the surface of the ground object

Generate - this drop down list sets the particle group to born the particles into.

Size - sets the particle size for new born particles

Mass - sets the mass of the particles

Speed - defines the initial speed of the new born particles.

Direction - sets the direction the particles travel when they are born. A value of 0 degrees will make the particles travel in +X with increasing angles the particles will travel in different clock wise directions.

Motion Inheritance - a multiplier used to add an amount of speed to the born particles, based on the WaterLevel object transformation.

Show -Check this option to display visual indicators of the volume that will be sued to create the particles. White lines indicate the filled volume, orange lines indicate the direction of the speed when particles are born

Count - displays the amount of particles that will be created. Show must be turned on for this option to work.