8

Event 1029
the Environment dialog map button to the
sample slot.
Note: To control whether or not the renderer
uses the environment map’s alpha channel in
creating the alpha for the rendered image, choose
Customize > Preferences > Rendering, and then
turn on Use Environment Alpha in the Background
Antialiasing group. If U se Environment Alpha is
turned off (the default) the backg round receives
an alpha of 0 (completely transparent). If Use
Env i ronment Alpha is turned on, the alpha
oftheresultingimageisacombinationofthe
scene and backg round image’s alpha. Als o,
when writing TGA files with Pre-Multiplied
Alpha set to off, turning on Use Environment
Alpha prevents incorrect results. Note that only
background images w ith alpha channels or black
backgrounds are supported when compositing in
other programs such as Photoshop.
Event
The event is the basic unit of organization in a
Particle Flow
particle diagr am (page 3–1083) .
There are two types of events:
global (page
3–1043)
and local (page 3–1057) .A birth event
(page 3–1010)
is a specialized type of local event.
1. Global event
2. Birth event
3. Local event
Each event contains one or more actions (page
3–997)
, which can affect p art icle behavior or
appearance. You can use
tests (page 3–1115) to
send particles to other events if the particles meet
certain qualifications. A single chain of linked
events as shown in
Particle View (page 2–121) is
known as a
flow (page 3–1036) .
Event Display
Theeventdisplay,themainwindowinthe Particle
View (page 2–121)
dialog, contains the particle
diagram (page 3–1083)
.Thisiswhereyoubuild
and edit the part icle system.