HTML and CSS Reference
In-Depth Information
Resetting the game
In the
run()
function, the
STATE_RESET
state calls the
resetApp()
function, which in turn
calls
startLevel()
. It also sets the volume of our two sounds to 50% (
.5
) before setting the
appState
to
STATE_PLAYING
:
function
function
resetApp
() {
startLevel
();
shootSound
.
volume
=
.
5
;
explodeSound
.
valume
=
.
5
;
appState
=
STATE_PLAYING
;
}
The
startLevel()
function traverses through two nested
for:next
loops, creating the rows
of aliens by column. Each time we create an alien, we push a dynamic object into the
aliens
array with the following properties:
speed
The number of pixels the aliens will move left or right on each call to
drawScreen()
.
x
The starting
x
position of the alien on the screen. This value is set by the column (
c
) mul-
tiplied by
ALIEN_SPACING
, added to
ALIEN_START_X
.
y
The starting
y
position of the alien on the screen. This is set by the row (
r
) multiplied by
ALIEN_SPACING
, added to
ALIEN_START_Y
.
width
The width of the alien image.
height
height
The height of the alien image.
Here is the code for the
startLevel()
function:
function
function
startLevel
() {
for
for
(
var
var
r
=
0
;
r
<
ALIEN_ROWS
;
r
++
) {
for
for
(
var
var
c
=
0
;
c
<
ALIEN_COLS
;
c
++
) {
