Question

90

finding angles 0-360

rated 0 times [ 94] [ 4] / answers: 1 / hits: 24962 / 15 Years ago, tue, november 10, 2009, 12:00:00

Need help with a math issue:
i need to get the true angle from 0 degrees using x and y cordinates
im using this at the moment:

Math.atan((x2-x1)/(y1-y2))/(Math.PI/180)

but /(Math.PI/180) limits results from -90 to 90
i need 0-360

note: I'm using the angle to indicate direction:

0=up

90=right

135=45 degree right+down

180=down

270=left

etc

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susanajamiep

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answered 15 Years ago aiyanakatelinp · Accepted Answer

Math.atan limits you to the two rightmost quadrants on the unit circle. To get the full 0-360 degrees:

if x < 0 add 180 to the angle

else if y < 0 add 360 to the angle.

Your coordinate system is rotated and inverted compared to mine (and compared to convention). Positive x is to the right, positive y is up. 0 degrees is to the right (x>0, y=0, 90 degrees is up (x=0,y>0) 135 degrees is up and to the left (y>0, x=-y), etc. Where are your x- and y-axes pointing?