2010

Table Of Contents
Like the nParticle Radius attribute, Opacity and Color can be set on a per
nParticle object or per-particle basis. Using the nParticle object's Shading
ramps, you can map per-particle Opacity and Color to nParticle properties
such as particle Age, Particle ID, and Radius.
To set nParticle Shading attributes
1 To make it easier to see the changes you make to the nParticle objects
Shading attributes, you can hide the Volume Axis field shape by selecting
Field_Smoke1 in the Outliner then selecting Display > Hide > Hide
Selection.
The Volume Axis field still affects your nParticles, but you no longer see
the volume shape in the scene view.
2 In the Outliner, select nParticle1_Smoke.
3 In the Attribute Editor, click the nParticle_SmokeShape1 tab.
4 In the Shading section, set Opacity to 0.1.
5 Play back the simulation.
Notice that the emitted nParticle cloud appears thinner and more like
cigarette smoke than before.
To further improve the appearance of the smoke as it rises and dissipates
in the air, you can use the Opacity Scale ramp to adjust the opacity of
individual nParticles as they age.
6 In the Opacity Scale section, click in the ramp to create additional markers
then set an Opacity ramp by setting the following marker settings:
InterpolationSelected
Value
Selected Posi-
tion
Marker
Spline0.9800.2991
Spline0.9150.5602
Spline0.5800.7093
Spline0.00.9844
7 Set Opacity Scale Input to Normalized Age.
As each nParticle ages from birth (emission), its opacity changes from
the opacity values specified by the left marker to the one specified by the
right marker.
944 | Chapter 19 nParticles