Game Development Reference
Radio Waves and Water Simulation
Because Radio Waves creates trails of circles, it's a superb effect to use when simulating water effects, such as a
pond ripple, or someone dragging their fi nger around on the surface of water. You can use Radio Waves as a displace-
ment map with the Caustics effect (discussed with the Simulation effects in Chapter 16). You can also use the Refl ection
property (the checkbox at the bottom of the Wave Motion properties) in the Radio Waves effect. The Refl ection property
creates refl ections of waves when they get close to the edges of a layer. This mimics the way waves travels in water, as
the forces that create water ripples bounce off objects at the water's edge.
increase this value. If you reduce this value suffi ciently, you will
create an object with fl at sides. Moving this value to 3, for exam-
ple, will create triangles. Increase the Curve Size and Curviness
values to create polygons with rounded edges. Or, you can check
the Star checkbox to create concentric stars.
The Wave Motion area contains some useful parameters also.
Expansion controls the speed at which the waves move away
from the Producer Point once emitted. Think of the caterpillar
from Alice in Wonderland blowing smoke rings into Alice's face.
The smoke came out quickly, traveling a great distance, and
then slowed down. To recreate that effect, we have to increase
the Expansion value. Orientation and Spin are similar, in that
both control the rotation of the waves (which is diffi cult to dis-
cern when your waves are circular). Orientation determines
the angle of the waves when fi rst emitted. To animate spinning
waves, animate the Spin property. Velocity controls the speed
at which waves are emitted. If the Velocity value is greater than
0, then you can use the Direction property to determine the
direction in which waves are emitted. The Lifespan property
determines—in seconds—how long each wave remains before it
When a wave's lifespan is over, it just vanishes. Poof. Gone. To
have it die out more gradually, adjust the Fade-out Time prop-
erty in the Stroke category. This, along with the other proper-
ties in the Stroke area determines the visual appearance of the
waves. The Fade-in Time property allows you to make waves fade
in as they are created. You can also regulate the starting and end-
ing size of the waves' stroke with the Start Width and End Width
In the Stroke area, you'll fi nd a Profi le drop down. This shapes
the profi le of the stroke used to create the wave. The default
value of Square is the most straightforward, as it is a standard
stroke—completely solid. The other options allow you to create
a semitransparent, gradual fade from opacity to transparency
( Fig. 9.38 ).