How to check angle in range?-CodePudding

For example: angle 10 is cross 270 ~ 390 , because 270 to 390 is inclue 270 ~ 360 and 0 ~ 30.

InRange(0, 180, 90);//true;
InRange(180, 270, 90);//false;
InRange(270, 390, 10);//false; <== but this is in range , How to fix?

And my method:

public bool InRange(int start, int end, int angle)
{
    if (angle >= start && angle <= end)
    {
        return true;
    }

    return false;
}

CodePudding user response：

Be careful!

The follwoging is not in range: InRange(270, 390, 10);//false;

Because: if (10 >= 270 && 10<= 390) => false

Because 10 is not bigger then 270

You should debug your program the next time, to find fast the bug.

CodePudding user response：

Be sure that range is normalized (390>270)

Find middle angle m = (270 390)/2 and half-angle h = (390-270)/2

Compare cosine of difference of needed angle a and middle one m with cosine of half-angle h (convert degrees to radians if needed in your language). This approach helps to avoid problems with periodicity etc

if cos(a - m) >= cos(h)  
    {a inside the range}