Java Calculating the angle between two points in degrees

Question

I need to calculate the angle in degrees between two points for my own Point class  Point a shall be the center point   Method   public float getAngle Point target        return  float  Math toDegrees Math atan2 target x - x  target y - y        Test 1     returns 45  Point a   new Point 0  0       System out println a getAngle new Point 1  1       Test 2     returns -90  expected  270  Point a   new Point 0  0       System out println a getAngle new Point -1  0       How can i convert the returned result into a number between 0 and 359

User · Answer

What about something like    angle   angle   360

User · Answer

I started with johncarls solution  but needed to adjust it to get exactly what I needed   Mainly  I needed it to rotate clockwise when the angle increased   I also needed 0 degrees to point NORTH   His solution got me close  but I decided to post my solution as well in case it helps anyone else   I ve added some additional comments to help explain my understanding of the function in case you need to make simple modifications          Calculates the angle from centerPt to targetPt in degrees     The return should range from  0 360   rotating CLOCKWISE      0 and 360 degrees represents NORTH     90 degrees represents EAST  etc          Assumes all points are in the same coordinate space   If they are not      you will need to call SwingUtilities convertPointToScreen or equivalent     on all arguments before passing them  to this function         param centerPt   Point we are rotating around      param targetPt   Point we want to calcuate the angle to        return angle in degrees   This is the angle from centerPt to targetPt      public static double calcRotationAngleInDegrees Point centerPt  Point targetPt           calculate the angle theta from the deltaY and deltaX values         atan2 returns radians values from  -PI PI          0 currently points EAST           NOTE  By preserving Y and X param order to atan2   we are expecting         a CLOCKWISE angle direction        double theta   Math atan2 targetPt y - centerPt y  targetPt x - centerPt x           rotate the theta angle clockwise by 90 degrees          this makes 0 point NORTH         NOTE  adding to an angle rotates it clockwise           subtracting would rotate it counter-clockwise     theta    Math PI 2 0          convert from radians to degrees        this will give you an angle from  0- gt 270   -180 0      double angle   Math toDegrees theta           convert to positive range  0-360         since we want to prevent negative angles  adjust them now         we can assume that atan2 will not return a negative value        greater than one partial rotation     if  angle  lt  0            angle    360             return angle

User · Answer

Why is everyone complicating this  The only problem is  Math atan2  x   y  The corret answer is Math atan2  y  x  All they did was mix the variable order for Atan2 causing it to reverse the degree of rotation  All you had to do was look up the syntax https   www google com amp s www geeksforgeeks org java-lang-math-atan2-java amp

User · Answer

you could add the following   public float getAngle Point target        float angle    float  Math toDegrees Math atan2 target y - y  target x - x         if angle  lt  0           angle    360             return angle      by the way  why do you want to not use a double here

User · Answer

angle   Math toDegrees Math atan2 target x - x  target y - y      now for orientation of circular values to keep angle between 0 and 359 can be   angle   angle   Math ceil  -angle   360     360

User · Answer

Based on Saad Ahmed s answer  here is a method that can be used for any two points   public static double calculateAngle double x1  double y1  double x2  double y2        double angle   Math toDegrees Math atan2 x2 - x1  y2 - y1           Keep angle between 0 and 360     angle   angle   Math ceil  -angle   360     360       return angle

User · Answer

The javadoc for Math atan double  is pretty clear that the returning value can range from -pi 2 to pi 2  So you need to compensate for that return value

[java] Java: Calculating the angle between two points in degrees

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