Game Development Reference
In-Depth Information
Accordingly, if you want the particle effect to emit a continuous, uninterrupted
stream of particles, the total particle count must be large enough and the life-
time and/or emit rate may need to be reduced.
Start size
and
End size
refer to the size of particles when they are spawned and when their
lifetime ends, respectively. The values are linearly interpolated during the lifetime of the
particle. Given that particle textures are square, the dimensions refer to both particle width
and height.
In this example, ignoring the variation values for a moment, the particles start out at
150x150 and after 6 seconds, the moment they disappear, their size will be 300x300.
That's pretty big for particle effects, but that size can be effective for creating large-scale
effects using relatively few individual particles.
Start spin
and
End spin
determine both the rotation of the particles at the start and end of
their lifetime as well as the speed of rotation. The rotation speed is determined by the dif-
ference between
Start spin
and
End spin
, which is linearly interpolated over the particle's
lifetime. If
Start spin
was
0
and
End spin
was
360
, the particles would rotate one revolu-
tion over their lifetime. Naturally, this rotation will be faster if the lifetime is 1 second
rather than 10 seconds.
The
Angle
sets the initial direction the particles take, in degrees and in counter-clockwise
direction. An angle of 0 degrees means the particles move to the right; an angle of 90 de-
grees means the particles move upward.
Start color
and
End color
determine the color and transparency that particles begin and
end their lives with. The colors are interpolated linearly over the lifetime of a particle.
If you want the particles to fade out smoothly toward the end, make sure to set the
Opa-
city
in the color wheel dialog to
0%
for the
End color
. If you want to avoid the particle
having to change its initial color over its lifetime, use black as the
End color
. Most com-
monly, particles are set up to end with the color black at
0%
opacity to create a nice and
smooth fade-out effect.
Blend src
and
Blend dst
are the same settings as for
Sprite
nodes. They affect how the
particles blend with the background. Unlike most other nodes that support blending,
particles default to additive blending. Basically, this means that particles brighten the
already existing background colors.
Most combinations of
src
and
dst
blend values just create more or less black rectangles.
Besides the two basic modes—
Normal
and
Additive
—I found that
Dst Color
for
src
with
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