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ICE Particle Size

The particle size defines how large the particles are. Some compounds use the Size value to help with collision detection or to define motion, such as the Bounce Off Surface or Stick to Surface compound. As well, instance geometry shapes inherit the particle Size value.

If you’re having display problems due to the particle size, especially with the wireframe or constant view type, try turning off the Advanced Hardware Particle Display option in your Display preferences (choose File > Preferences and click Display). This option activates hardware optimizations for displaying particles, but may cause problems with certain graphics hardware.

Setting the Initial Particle Size

To set the initial particle size

1. Create a particle emission—see Creating ICE Particle Emissions.

2. Open an Emit compound’s property editor and set a value for the Size parameter, which is the radius of the particle in Softimage units when using spheres or disc shapes (radius is half the diameter).

You may notice that ICE particles seem to be larger when using the same Size values as you’re used to with the standard non-ICE particles. This is because they use a different system of measurement.

Modifying the Particle Size Over Time (Size Shift)

To have a particle change size over its lifetime, you can use the Modify Particle Size compound. This compound modifies the particle size over time using different values and a profile curve. This makes it easy to create a size shift based on different factors such as the particle’s age or age percentage, or the length of the simulation.

To change the particle size over time

1. Create a particle emission—see Creating ICE Particle Emissions.

2. Click the Task > Particles tab in the preset manager on the left side of the ICE Tree.

3. Select the Modify Particle Size compound from the Modifiers group, and drag it into the graph area.

Plug this compound’s Execute output into a port on the ICETree node. You can also plug it into any Execute port of other compounds such as Slide on Surface, Bounce on Surface, or Stick to Surface. For example, you can start changing the particle size when it sticks to a surface.

4. Open the Modify Particle Size property editor and set the properties. The profile curve gives you control over how the particle size changes over time.

If you use Age Percentage as the Source Parameter, you must first define the particle’s age limit using the Set Particle Age Limit compound (see ICE Particle Lifespan).

For more information on the parameters, click the ? icon in the property editor or see Modify Particle Size.

Randomizing or Turbulizing the Particle Size

There are several compounds on the Task > Particle tab that let you add randomness or turbulence (noise) to the Size value so that the particles are not all emitted at the same size. Adding randomness or noise helps the particles look more natural for certain types of effects.

These compounds include:

• Emission Control > Randomize Emitter Value and Turbulize Emitter Value

• Modifiers > Randomize Value by Range and Turbulize Value by Range

• Modifiers > Randomize Around Value and Turbulize Around Value

See Modifying ICE Particle Values for information on each one of these compounds.

Particle Size and Scale Attributes

There are several particle attributes that are used to define particle size. These attributes are used in several compounds, but you can also use them on their own in an ICE tree by specifying them in the Get Data and Set Data nodes, as described in Using ICE Particle Attributes.

For more information on attributes in general and a list of all available ICE attributes, see ICE Attributes.

If you’re using particles as rigid bodies, you should also see Making ICE Particles into Rigid Bodies for information on the CollisionSize and CollisionScale attributes.

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