HTML and CSS Reference
In-Depth Information
reload time is checked, and only after the
Enemy
reloads its weapons does it check against a randomly gener-
ated number to see if it should
fire
.
If you load up the game, you should have enemies firing missiles as expected; however, all the enemies will
be firing just one missile at the same frequency.
To adjust the frequency of firing, you need to modify the enemy blueprints at the top of
game.js
. Modify
the
enemies
array to have the
ltr
and
wiggle
enemies each fire two missiles at a time (matching their
sprite image) and reduce the
firePercentage
of the
straight
and
wiggle
enemies to
0.001
to pre-
vent them from firing too many missiles at once, as shown here:
var enemies = {
straight: { x: 0, y: -50, sprite: 'enemy_ship', health: 10,
E: 100
, firePercentage: 0.001
},
ltr: { x: 0, y: -100, sprite: 'enemy_purple', health: 10,
B: 75, C: 1, E: 100,
missiles: 2
},
circle: { x: 250, y: -50, sprite: 'enemy_circle', health: 10,
A: 0, B: -100, C: 1, E: 20,
F: 100, G: 1, H: Math.PI/2 },
wiggle: { x: 100, y: -50, sprite: 'enemy_bee', health: 20,
B: 50, C: 4, E: 100,
firePercentage: 0.001,
missiles: 2
},
step: { x: 0, y: -50, sprite: 'enemy_circle', health: 10,
B: 150, C: 1.2, E: 75 }
};
With that, reload the game, and you should have a playable game with active enemies. You can also play the
game at
http://mh5gd.com/ch3/fair/
.
Summary
It's been a whirlwind in the first three chapters, having gone from making the first few marks onto the canvas to
building a fully functional mobile space shooter. As a demo game,
Alien Inva
sion isn't bad, but as a full-fledged
space shooter there's still lots that could be done: high scores, ship animations, sounds, longer and varied levels,
new enemies, and boss fights. The good news is that the code on Github at
https://github.com/cykod/AlienIn-
vasion
can be forked and enhanced. If you've been following along, you've stepped through every line of the
game and should know it inside and out. Check the readme file for what others have done.
