2009

2953 if it defines the rotation channel) in the same event. In this situation, the
Go To Rotation test can grab the particle rotational component before the
orientation-type operator overwrites it. The Go To Rotation operator modifies
the particle orientation and spinning in the post-evaluation cycle. For an
example, see the procedure below.
WARNING The Go To Rotation test is not compatible with the Spin, Shape Facing,
and Shape Mark operators. Do not use any of these operators in the same event
with a Go To Rotation test.
NOTE You can define the transition period only in terms of time. You cannot set
the test to come to a specific rotation by the time of another test, such as a collision
test. Also, limited control is provided over the axis of spinning when a particle
comes to the final rotation.
Procedures
Example: To make falling particles land smoothly, face up:
This procedure assumes a basic knowledge of Particle Flow usage.
1 In the Perspective viewport, add a Particle Flow system and raise its icon
about 80 units on the Z axis.
2 In Event 01, make the following changes:
■ Birth > Amount=50
■ Speed=100
■ Shape=Cube (or use Shape Instance with a custom object, such as a
coin-shaped cylinder)
■ Display > Type=Geometry
This reduces the number of particles and slows them down, making it
easier to see what's going on.
3 Add a
Spin operator on page 2863 to Event 01, and set both Spin Rate and
Variation to 150.
This gives the particles random spinning behavior as they fall.
4 Add an Age test to the end of Event 01, and set Test Value=15.
This allows each particle to fall and tumble for 15 frames before Go To
Rotation takes effect.
2982 | Chapter 14 Space Warps and Particle Systems