In the first step of creating your liquid simulation, you fill a polygon water pitcher with Water style nParticles. To do this, you use the Fill Object option.

To create a Water style nParticle object

1. Select nParticles > Create nParticles > Water.

   Selecting a Water style nParticle object presets some nParticleShape attributes including turning on Liquid Simulation attributes, turning off nParticle Self Collisions, and setting the Particle Render Type to Blobby Surface.

2. In the Outliner, select geo_pitcher, which is grouped in the grp_Pitcher object.

   This is the geometry that you will fill with Water style nParticles.

3. Select nParticles > Create nParticles > Fill Object > .

   The Particle Fill Options window appears.

   
4. In the Particle Fill Options window, select Edit > Reset Settings.
5. Set the following Particle Fill Options:
   • From the Solver list, select Create New Solver.
   • Set Resolution to 20.

     Resolution specifies how many nParticles are evenly placed along the geometry’s longest axis.

   • Set Max Y to 0.5.

     When set to 0.5, nParticles half-fill the pitcher.

   • Ensure that Close Packing is turned on.
   • Turn on Double Walled.

     Turning on Double Walled ensures that the thickness of the pitcher geometry is taken into account when it is filled with nParticles. The particles now only fill the pitcher's empty volume, rather than the space between the polygon walls.

   For information about Particle Fill Options, see nParticles > Create nParticles in the nDynamics guide.

6. Click Particle Fill.

   Maya creates the nParticle object inside the water pitcher geometry.

   
7. In the Outliner, double-click nParticle1 and rename it to nParticle_Water.

   Renaming your nParticle object makes it easier to identify when you have more than one particle system in your scene.

   In this lesson, both the pitcher and the glass mesh will hold nParticles, so you must convert meshes to passive collision objects and assign them to the same Nucleus system as the nParticles.

To convert the pitcher and glass meshes to passive collision objects

1. In the scene view, -select the pitcher and glass meshes.
2. Select nMesh > Create Passive Collider > .

   The Make Collide window appears.

   
3. From the Solver list, select nucleus1.
4. Click Make Collide.
5. To rename the pitcher and glass nRigid objects, in the Outliner, double-click nRigid1 and nRigid2, and type nRigid_Pitcher and nRigid_Glass respectively.
   
6. Play the simulation.

   When you play the simulation, notice that the nParticles do not behave as you might expect. Rather than immediately falling to the bottom of the pitcher like water, they fall slowly, as if the simulation is playing in slow motion. To make the nParticles behave realistically, you can set the Nucleus Space Scale for the simulation.

   For more information about Space Scale, see Adjusting Nucleus Space Scale.

To set Space Scale

1. In the Attribute Editor, click the nucleus1 tab.
2. In the Scale Attributes section, set the Space Scale to 0.01.
   

   When you reduce the Space Scale value, Maya evaluates the nParticle system as if the particles are much smaller in size. This results in a visibly increased gravitational effect on the nParticles.

3. Rewind the simulation to the start frame, and then play it back.
   

   When you play the simulation, notice that the nParticles are still contained in the pitcher, but they occupy a small amount of the pitcher’s volume. Also, the nParticles appear to be pushing down as if they are under a force of pressure or compression. In the next section, you begin adjusting the Liquid Simulation attributes that make the nParticles look and behave more like a liquid.