Using atan2 to find angle between two vectors

by 
 atan2(vector1.y - vector2.y, vector1.x - vector2.x)

is the angle between the difference vector (connecting vector2 and vector1) and the x-axis,
which is problably not what you meant.

The (directed) angle from vector1 to vector2 can be computed as

angle = atan2(vector2.y, vector2.x) - atan2(vector1.y, vector1.x);

and you may want to normalize it to the range [0, 2 π):

if (angle < 0) { angle += 2 * M_PI; }

or to the range (-π, π]:

if (angle > M_PI)        { angle -= 2 * M_PI; }
else if (angle <= -M_PI) { angle += 2 * M_PI; }

More Related Contents:

  1. How do I calculate the normal vector of a line segment? [closed]
  2. Signed angle between two 3D vectors with same origin within the same plane
  3. Calculate distance between 2 GPS coordinates
  4. Generate a random point within a circle (uniformly)
  5. How to determine if a list of polygon points are in clockwise order?
  6. A simple algorithm for polygon intersection
  7. Turning a cylinder into a sphere without pinching at the poles
  8. Finding quaternion representing the rotation from one vector to another
  9. How to calculate the volume of a 3D mesh object the surface of which is made up triangles
  10. Cone to box collision
  11. Calculating area enclosed by arbitrary polygon on Earth’s surface
  12. How do I combine complex polygons?
  13. correcting fisheye distortion programmatically
  14. Implementing Ray Picking
  15. Rotating a Vector in 3D Space
  16. How do I detect intersections between a circle and any other circle in the same plane?
  17. Projecting 3D points to 2D plane [closed]
  18. How to distribute points evenly on the surface of hyperspheres in higher dimensions?
  19. Perpendicular on a line from a given point
  20. Finding the coordinates of points from distance matrix
  21. how map 2d grid points (x,y) onto sphere as 3d points (x,y,z)
  22. 3D coordinates on a sphere to Latitude and Longitude
  23. Calculate rotated rectangle size from known bounding box coordinates
  24. How to best approximate a geometrical arc with a Bezier curve?
  25. Get bounds of rotated rectangle
  26. Algorithm to detect intersection of two rectangles?
  27. How do you calculate the average of a set of circular data? [closed]
  28. Solving a linear equation
  29. How to tell whether a point is to the right or left side of a line
  30. Calculate a point along the line A-B at a given distance from A

Leave a Comment