I've got a game object i need to rotate. It's current angle is player.rotation, the destination is targetAngle, both in degress, 0 to 359. I've got a function named rotateDirection(float sourceAngle, float destAngle) that needs to return -1 or 1 depending on whether the shortest way to reach the destination angle would be clockwise or counterclockwise.

For example - for sourceAngle 300 and destAngle 0 the function would return 1 for clockwise.

The solution is most probably going to leave me looking silly, and i usually don't like just asking for code, but my brain is completely broken so please help me with this one :)


1 Answer 1


This should do:

(((source-dest+360) mod 360)>180)?1:-1

The +360 is only necessary for languages with a fuzzy mod function. Note that most languages implement fuzzy mod.

  • \$\begingroup\$ hey, thanks for the answer. It seems to be returning -1 for source=3 dst = 38, which is an error... \$\endgroup\$ Commented May 3, 2011 at 23:38
  • \$\begingroup\$ Zaky: It returns 1 for source=3, dest=38. It reduces to 325>180 which is true, so it returns 1. \$\endgroup\$
    – Olhovsky
    Commented May 3, 2011 at 23:47
  • \$\begingroup\$ this does not work for me ! sorry for giving you a +1 \$\endgroup\$
    – Vishnu
    Commented Jan 9, 2012 at 11:11
  • 2
    \$\begingroup\$ @Vish No hard feelings. The code is fine, but of course there are countless ways of incorporating it into a whole in a way that does not produce the desired result. \$\endgroup\$ Commented Jan 9, 2012 at 14:24
  • \$\begingroup\$ I'm sorry eBusiness , but today I tried your code with the +360 thing and it worked. The word fuzzy mod function was what caused the confusion. Thank you :) \$\endgroup\$
    – Vishnu
    Commented Jan 25, 2012 at 7:25

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