I have my base class for all projectiles (rockets, bullets) that contains an X,Y,Angle and Speed integers. Now, what formula can I use so that if the angle is say, 45 degrees and the speed is ten, it would move the X 5 pixels and the Y -5 pixels. I had one once, but I lost it. Damn. Any help? Yo Tyler, I hear your mum''s goin out with... SQUEEK!

Convert your angle from degrees to radians, then do this:

x += sinf(angle) * speed;
y += cosf(angle) * speed;

or it might be:

x += cosf(angle) * speed;
y += sinf(angle) * speed;

[edited by - YodaTheCoda on February 22, 2003 12:12:13 AM]

This might help:

#define ToRadian(x) ((x) * (PI / 180.0f))

Oh, Ok, I''ll go try that now.

Yo Tyler, I hear your mum''s goin out with... SQUEEK!

and in case you havent got an accurate(ish) definition of PI...

#define PI 3.1415926535

Oh, yeah. I''ll probably need that.

Yo Tyler, I hear your mum''s goin out with... SQUEEK!

Ok, that worked, but I just need to correct you (cause I don''t often get to)
I found that I needed to add a +90 to the angle. Don''t tell me I''m doing something wrong, cause this works so... yeah.

Thanx!!

Yo Tyler, I hear your mum''s goin out with... SQUEEK!

you are doing it wrong. You must be doing
x=sin(angle)*speed
y=cos(angle)*speed

when it should be
x=cos(angle)*speed
y=sin(angle)*speed

and because sin(a+90)=cos(a), if you got the two reversed you would have to make the correction you made to get it to work.

Yeah well, it''s programmed now so I''ll leave it. Thanks anyway.

Yo Tyler, I hear your mum''s goin out with... SQUEEK!