Hi, first time posting here. I'm having problems with some trigonometry calculations in as3. Here's the swf file, i can move the ship forwards and backwards but things get weird when i try to move it sideways.

Here's the code;

//this moves the ship forward
vx += Math.cos(rotation* Math.PI / 180) * 3;
vy += Math.sin(rotation* Math.PI / 180) * 3;

//and this should move the ship to its right
vx += Math.cos((rotation+90)* Math.PI / 180) * 3;
vy += Math.sin((rotation+90)* Math.PI / 180) * 3;

I have no idea what i'm doing with these stuff i just took the calculations from a tutorial. Why this isnt working?

Thanks in advance!

ps: Here's some additional info;

//ship's location is updated like this in every tick
x+=vx;
y+=vy;

//and i calculate the angle of the ship like this;
rotation = (Math.atan2(y-stageRef.mouseY,x-stageRef.mouseX)*180/Math.PI)+180;

Hi there

Your mathematics is perfectly legitimate here, everything is as it should be at a glance.

It might be fixed ( it's a bit "meh" ) by making sure you calculate the angle at each tick BEFORE doing the movement.

Hope it helps.

Daniel Kruyt

Nature of Code book was super helpful for me here -

http://natureofcode.com/

He's got some really great vector math and physics stuff I found super useful.

what's the problem, the swf appears to behave perfectly correctly.

If you plan on making games it's well worth your time to look up some basic trig and see what those functions are doing and why.

I also don't see a problem here. Can you explain more precisely what it's not doing correctly?

I updated it yesterday but its still broken. I don't want the ship to move away from the mouse when i'm only pressing "a" or "d" buttons.

Nature of Code book was super helpful for me here -

http://natureofcode.com/

He's got some really great vector math and physics stuff I found super useful.

I'ts seems nice and cheap gonna check it out thanks!

Since you always face the centre point, do moving forwards and backwards as you do now, but when you have a clockwise/counterclockise component to your velocity, rotate around the focus point the correct amount of degrees to match the given speed. You can work out how many degrees to travel since you know moving 360 degrees would be a speed of 2 * PI * r where r is the radius of the circle you travel around (i.e. distance between the ship and the focus point).

Does that make sense?

Uhm.. I'm not very good at english and when its combined with trigonometry it makes no sense to me. I cant understand the last sentence. I can calculate the distance between two points but i dont know what should i do with it.

Edit: By the way sorry for the late response i was waiting to get a mail from gamedev.net informing me when i got some answers, it didnt happen.

Edit2: I uploaded the source here if it helps. Some parts are in turkish but i can translate the source if needed.

You can work out the angle you are at with respect to the centre of the circle using atan2.

Dont i know the angle already? From the rotation variable?