covert sparrow rotation radians to trig radians

Excelcius

Hi all Ive got a bit of a head twisting problem, Im trying to convert Sparrows rotation radians 0 being up 3.14 -3.14 being down 1.57 being right and -1.57 being left to trig radians 1.57 being up -1.57 being down 0 being right and 3.14 being left. Does anybody know of a simple function to achieve this and back again ?

Thanks in advance

humble

Easiest I find it is thinking about the unit circle. So no rotation ie up is 0 degrees. Then 90 degrees is PI/2, half a circle PI, a whole circle 2 * PI. If you have a negative angle doesn't matter, same thing if you just add a whole circle, you end up with the same rotation.

If you still want to rotate the unit circle so your up is at the unit circles 0 degrees, simply shift it 90 degrees.

unitcircle.angle = sparrow.angle + 90 degrees;

Hope that makes sense...

ERik

Excelcius

Hi humble thank you for your reply Ive been beavering away at the problem and I think Ive come up with a solution. Im just working on a way to convert it back the other way, and convert to degrees 0 being up 180 being down, Ive tested and it seems to work but its twisted my head a bit so if you or anybody else can see a flaw in my code or suggest a more efficient way of doing it I would greatly appreciate it.

+ (float) TR2SR:(float)rad
{
    rad = (rad - PI_HALF) * -1;

    return [QPMaths clampRadians:rad];
}

+ (float) clampRadians:(float)r
{
    float d = (r > 0) ? TWO_PI : -TWO_PI;
    r = fmod(r, d);

    return (r > PI || r < -PI) ? r - d : r;
}