2009

To use the Use Icon Orientation option:
The Use Icon Orientation option applies arc-like motion to the particles based
on rotation animation of the icon. To best understand how it works, it's
necessary to isolate its influence by eliminating any potentially conflicting
factors.
1 Reset the software, and then add a Particle Flow system in the Perspective
viewport. Set its position to the world origin: (0,0,0).
2 Open Particle View and click the Birth operator. Set Emit Stop=0.
This causes all particles to appear at frame 0.
3 Click the Speed operator and press the Delete key to delete it.
4 Drag a Speed By Icon operator from the Depot to the end of Event 01.
The Speed By Icon operator icon appears at the world origin.
5
Select the Speed By Icon operator icon, and then right-click
the icon and choose Rotate from the menu. Go to frame 20, turn on Auto
Key, and rotate the icon 180 degrees about the X axis.
6
Turn off Auto Key.
7 Drag the time slider.
The particles aren't affected by the icon animation.
Because the Speed By Icon operator icon is selected, the operator's
parameters appear on the Modify panel.
8 On the Modify panel, turn on Use Icon Orientation. Drag the time slider
again.
This time, the particles move in unison with the icon rotation, as if they
were glued to an infinite plane coincident with the icon.
9 Go to frame 10, select the Particle Flow source icon (not the Speed By
Icon operator icon), and then right-click the icon and choose Move from
the menu. Move the icon straight up, on the Z axis, about 100 units.
As you drag upward, the particles move away from the icon.
10 Drag the time slider again. This time the particles move in an arc around
the icon.
2882 | Chapter 14 Space Warps and Particle Systems