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Finding an angle between 2 objects (2D)

Started by Bluefox Mar 19, 2003 at 8:32 AM 3 replies 250+ views

Original Post

Mar 19, 2003 at 8:32 AM

Im trying to find the angle from the gunship to the beacon, using the atan2() funtion to get the angle, so it can turn round and face it. The values being returned to me dont make much sense, do I need to convert to degrees - if so how? new_x = GunShip->x - Beacon->x; //x distance new_y = GunShip->y - Beacon->y; //y distance GunShip->new_direction = atan2(new_y,new_x);

Stary

Mar 19, 2003 at 8:43 AM

Yes, you need to convert it to degrees. As you''ll find if you ever looked in a manual or help page or documentation, the atan2 function returns a value in the range [-pi, pi]. If you don''t know how to convert radians to degrees, google will serve you well.

poisonfruitloops

Mar 19, 2003 at 8:58 AM

hi i''ve think i have sumthin i''ve been using that may be of help...

i -think- there may be a bug in it sumwhere but here it is:

angle = atan(fabs(relativeObject.X) / fabs(relativeObject.Y)) * (180 / pi);

if (relativeObject.X > 0 && relativeObject.Y > 0)
// front-right
returnAngle.set(angle, 0, 0);
else if (relativeObject.X > 0 && relativeObject.Y < 0)
// back-right
returnAngle.set(180 - angle, 0, 0);
else if (relativeObject.X < 0 && relativeObject.Y < 0)
// back-left
returnAngle.set(180 + angle, 0, 0);
else if (relativeObject.X < 0 && relativeObject.Y > 0)
// front-left
returnAngle.set(360 - angle, 0, 0);

u may need to hack it up a little but i hope it helps

Bluefox

Author

Bluefox

Mar 19, 2003 at 9:50 AM

Thanks for the replies, you both been helpful.

JohnBolton

132

JohnBolton

Mar 19, 2003 at 2:36 PM

quote:
Original post by poisonfruitloops
angle = atan(fabs(relativeObject.X) / fabs(relativeObject.Y)) * (180 / pi);

Don''t use atan -- you will get divide-by-0. Use atan2 .

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