Visual Effects and Animations - Learn SpriteBuilder for iOS Game Development - page 420

To create truly orbiting particles, you have to set the particle emitter to radial mode. Then
you can edit the Start radius and End radius to determine the radius of the orbit of the
particles, either moving outward or inward. Or set both Start radius and End radius to the
same radius, only adjusting the variance, to create a ringlike effect.
The Rotate property is the angle (in degrees) that the particles will move around the emit-
ter's position every second. You will see the particles orbiting from Start radius to End
radius only if you specify a decent Rotate value and the particle lifetime is long enough.
Tip You may find it easier to design certain effects by leaving all variation val-
ues at zero initially. The variation values are the property fields to the right of
the plus/minus sign. Also, try to focus on editing one aspect of the particle ef-
fect at a time. And do edit particle effects in a stage that at least resembles a
possible use case. If you test a particle effect against a simple color (or gradient)
background, you can't really judge what the effect looks like in the game.
Particle effects can look very different depending on the background they blend
with.
You may want to design the particle effect in a Node CCB and then (temporar-
ily) add various test-scene CCBs as the background node for the particle CCB.
This allows you to quickly toggle through possible particle emitter backgrounds
by using the visibility property. The test scenes would be specifically made to
look like a typical use case in the game.
Finally, the Texture property is just like the Sprite frame property of sprite nodes.
SpriteBuilder comes with five built-in particle textures that you'll find in the ccbRe-
sources folder with names starting with ccbParticle . They are sufficient for many uses,
but of course you can use your own particle textures. Be sure to design the particle tex-
tures as square images.
Though particles can use any texture size allowed by a device, it is strongly recommended
that you use the smallest possible texture. The size of a particle texture can significantly
affect the effect's performance. In most cases, particles blend really well even when using
a very low resolution texture.
Figure 12-7 shows what the result of the particle effect might look like if you applied the
same values or similar values as in Figure 12-5 and Figure 12-6 to the Particle System
node.