How to shoot bullets depending on how something is rotated in a game

anacanm

Hi everyone,

I'm making the classic Arcade game Asteroids, and i've got movement all down and shooting a missile. The problem is, I dont know how to shoot a missile in the direction that I'm pointing, and since the ship is always rotating, the rotation is always changing. How would I do this?

Thanks in advance,

Anacan

heres my code at the moment:

http://hastebin.com/eciwilulom.java - thats the main class

http://hastebin.com/ulayoworur.java - thats the missile class im using

koogs

basic trigonometry.

if something is moving in a direction given by angle a at a given speed s then it moves s * cos(a) in the x direction and s * sin(a) in the y direction with evey step.

koogs

in your case

Missile(float xstart, float ystart, float xv, float yv)

xv and yv should reflect the above when you instantiate Missile.

you are currently calling it with m = new Missile(x,y,5,5); so the missile will just move diagonally, regardless of where the ship is pointing.

it's similar to how you are calculating x and y just before that.

koogs

and please don't start duplicate threads. there are three of these now, all very similar.

jeremydouglass

So, for velocity arguments xv, yv:

m = new Missile(100,100, 5,5);

down 5 and right 5.

m = new Missile(100,100, -7,0);

left 7.

Pick numbers based on which way the ship is facing.