Game Development Reference
In-Depth Information
onscreen buttons are being pressed. Additionally, the ship will keep track of the number of lives
it has, and offer us a way to tell it that it has been killed. Listing 12-8 shows the code.
Listing 12-8. Ship.java, the Ship Class
package
com.badlogic.androidgames.androidinvaders;
import
com.badlogic.androidgames.framework.DynamicGameObject3D;
public class
Ship
extends
DynamicGameObject3D {
static float
SHIP_VELOCITY
= 20f;
static int
SHIP_ALIVE
= 0;
static int
SHIP_EXPLODING
= 1;
static float
SHIP_EXPLOSION_TIME
= 1.6f;
static float
SHIP_RADIUS
= 0.5f;
We start off with some constants to define the maximum ship velocity, two states (alive and
exploding), the amount of time it takes the ship to explode fully, and the ship's bounding sphere
radius. Also, we let the class derive from
DynamicGameObject3D
, since it has a position and
bounding sphere, as well as a velocity. The acceleration vector stored in a
DynamicGameObject3D
will again be unused.
int
lives;
int
state;
float
stateTime = 0;
Next we have the members, consisting of two integers, to keep track of the number of lives the
ship has and its state (either
SHIP_ALIVE
or
SHIP_EXPLODING
). The last member keeps track of
how many seconds the ship has been in its current state.
public
Ship(
float
x,
float
y,
float
z) {
super
(x, y, z,
SHIP_RADIUS
);
lives = 3;
state =
SHIP_ALIVE
;
}
The constructor performs the usual super class constructor call and initializes some of the
members. The ship will have a total of three lives.
public void
update(
float
deltaTime,
float
accelY) {
if
(state ==
SHIP_ALIVE
) {
velocity.set(accelY / 10 *
SHIP_VELOCITY
, 0, 0);
position.add(velocity.x * deltaTime, 0, 0);
if
(position.x < World.
WORLD_MIN_X
)
position.x = World.
WORLD_MIN_X
;
if
(position.x > World.
WORLD_MAX_X
)
position.x = World.
WORLD_MAX_X
;
bounds.center.set(position);
}
else
{
if
(stateTime >=
SHIP_EXPLOSION_TIME
) {
lives--;
