Thread: rotating to a target direction

I have an object defined with x,y, and th, right? What I want to be able to do is point to another location and have the object turn until it's pointing towards that location in the shortest way possible. So far I've come up with:

Code:

if(th < targetth)
  th += dth;
if (th > targetth)
  th -= dth;

The problem with this is that when the target location goes across the positive y access the object spins all the way around the other way. How can I have it reach the targetth in the shortest possible distance every time?

Something along the lines of

Code:

dir = 1;
if( th - target_th > 180 ) dir = -1;

if(th < targetth)
  th += dth * dir;
if (th > targetth)
  th -= dth * dir;

If the angle difference is greather then 180, go the oppisite direction you would normally go.

Need to toss in an ABS() some where in there.