motion according to rotation

[Swas]

im creating a mini game for my big game in which u must flick coins between each other (not gonna say details koz im too lazy) basically i have a full engine going the only thing i cant get right is the title, when each coin is click it is selected and you can rotate using the left a right arrow keys, when u press space a power bar builds up and when u release it, it "flicks" the coin according to that, but i cant figure out a way to get it to fire in the direction of the rotation, im guessing im gonna have to use trig? please help, ill be finished in when if someone helps

[DarkReality]

English would be a start? Like... periods.

www.actionscript.org/tutorials has a good tutorial on trig and angle movement. Basically, it's trig. And a bit too much effort for me to want to explain right now, sorry. But that tutorial won't run away. Most likely.

[Nexus]

Assuming you already have the angle of direction in degrees, you would do something like...

//Calculate directional force
this.vx = Math.sin(angle*(Math.PI/180))*power;
this.vy = -Math.cos(angle*(Math.PI/180))*power;
//Moves coin and applies friction (put in onEnterFrame)
this.vx *= 0.9;
this.vy *= 0.9;
this._x += this.vx;
this._y += this.vy;

The concept behind this isn't hard. I'm suprised there hasn't been a tutorial that makes it easy to understand sine and cosine. Most of the tutorials I see make it way more complicated than it really is.

Hope this helps you out.

[Swas]

it does kinda theres just a couple of problems with it can u tell me whats wrong with my code, it fires in the direction, if its left it fires down, right up, up right, down left im confused onClipEvent (mouseMove) {
if (this.c1control == true) {
x = this._xmouse;
y = this._ymouse*-1;
angle = Math.atan(y/x)/(Math.PI/180);
if (x<0) {
angle += 180;
}
if (x>=0 && y<0) {
angle += 360;
}
_root.coinOne.rotate._rotation = angle*-1;
}
updateAfterEvent();
}
onClipEvent (enterFrame) {
if (this.c1control == true) {
if (Key.isDown(Key.SPACE)) {
this.vx = Math.sin(angle*(Math.PI/180))*_root.powerbar.scale;
this.vy = -Math.cos(angle*(Math.PI/180))*_root.powerbar.scale;
this.vx *= 0.9;
this.vy *= 0.9;
this._x += 0;
} else {
this._x += this.vx;
this._y += this.vy;
}
}
}



changing a few things around produces the desired effect apart from the weird directions it works in some directions but not others :S it confusing
it now moves in the way i want with the friction applied

onClipEvent (mouseMove) {
if (this.c1control == true) {
x = this._xmouse;
y = this._ymouse*-1;
angle = Math.atan(y/x)/(Math.PI/180);
if (x<0) {
angle += 180;
}
if (x>=0 && y<0) {
angle += 360;
}
_root.coinOne.rotate._rotation = angle*-1;
}
updateAfterEvent();
}
onClipEvent (enterFrame) {
if (this.c1control == true) {
if (Key.isDown(Key.SPACE)) {
this.vx = Math.sin(angle*(Math.PI/180))*_root.powerbar.scale;
this.vy = -Math.cos(angle*(Math.PI/180))*_root.powerbar.scale;
this.vx *= 0.9;
this.vy *= 0.9;

} else {
this.vx *= 0.9;
this.vy *= 0.9;
this._x += this.vx;
this._y += this.vy;
}
}
}

[Nexus]

What function are you using to get the angle of direction?

If you're using Math.atan2() then I think you need to subtract 90 degrees from the original value. That's why you're getting right as up and such. Try adding 90 or subtracting 90 to the _rotation attribute along with what you are already adding.

[Swas]

im using math.atan, whats the difference between atan2 and atan, its weird tho because in some directions it goes the right way


i had a go, if i send u it would u be able to have a lil look at it ?

[denacioust]

Math.atan would be on a calculator just tangent its for finding the tan of an angle. Atan2 is used to find an angle using two lines

[Nexus]

Math.atan2() is the better version. Math.atan() I believe only returns an angle ranging from 0 to 1/2PI. Math.atan2() returns 0 to PI. (thus achieves full-360 degree angle detection.

[The Brown Cow]

Math.atan() takes one argument, Math.atan2() takes two.

As far as I know, there's no difference between...
Math.atan(y/x);
and
Math.atan2(y, x);

Strange. Everyone uses atan2 though. Nexus' theory is probably right.

[Swas]

o, ok well anyway ive use tan, does any1 have any ideas on whats wrong and how i could fix it

[Swas]

hey i figured out was i did wrong, not coding but very stupid stupid animating errors ?, i had rotated the movie clip on the stage without using action script, thats why it was going in weird directions, heh kinda funny that it caused me so much grief :p thanx anyway thought u might like to know