Game Development Reference
In-Depth Information
In Layman's terms, what can be seen in each graph is a kind of lookup table. The
function of one of these algorithms takes the
alpha
value (
x
axis) as its input
and outputs the corresponding interpolated value (
y
axis). The actual output
simply depends on the algorithm's curve and what
alpha
value is used. The label
below each graph also denotes the name of the method, which you will find in
Interpolation
. Also, note that each algorithm reverses its effect at an
alpha
value
of
0.5
. There are variants of each method for an algorithm in case you may want
to apply a certain effect on the first half (
alpha
from
0.0
to
0.5
) or on the second
one (
alpha
from
0.5
to
1.0
) only. This can be achieved using the
In
or
Out
suffix,
respectively, such as
fadeIn
,
pow4In
, and
swingOut
.
The basic usage of
Interpolation
looks as follows:
float alpha = 0.25f;
float interpolatedValue = Interpolation.elastic.apply(alpha);
This code example finds the interpolated value (
y
axis) for a given
alpha
value (
x
axis) of
0.25
using the elastic algorithm. Remember, the
alpha
value can also be
interpreted as progress (here, 25 percent) of the overall effect.
With this in mind, we will now start to implement three distinct effects, namely fade,
slide, and slice.
Creating a fade transition effect
We will now create a fade transition effect that we will use to switch from the menu
screen to the game screen. In this effect, the next screen overlays the current screen
while gradually increasing the next screen's opacity. The opacity will start at 0
percent (fully translucent) and end at 100 percent (fully opaque).
The following sequence of screenshots shows this effect:
