OpenGL Compass

maybe you could use the look vector of your avatar (that is holding the compas) and define a north vector (maybe {0,0,-1} or something) and then use the angle between these to vectors to compute the value on the compas (I dont know how compas'' work... cuz i faild scouts ).

well i was thinking of just making a 3-D compass, 4 ends, one with N, E, S, W. then as you turn in the 3d world, the compass turns accordingly.. i am trying to possibly get this to make it easier for me to compute the lat,lon that i am at. how do you do this btw? this is not trivial..

Asuming your using 2 vertices for your camera, a from and a to point. Find the angle on your horizontal plane (XZ?) to a given point (0,1 XZ). Rotate your compass model the opposite angle.


Clear
LoadIdentity
Translate(compass position);
Rotate(0,1,0, - atan2(lookfat.x - lookfrom.x, lookat.z - lookfrom.z))
DrawCompass
SetCamera(lookfrom, lookat)
Draw rest of world


Looks good in words too me.