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This gives a signed angle for any angles:

a = targetA - sourceA a = (a + 180) % 360 - 180 

Beware in many languages the modulo operation returns a value with the same sign as the dividend (like C, C++, C#, JavaScript, full list here). This requires a custom mod function like so:

mod = (a, n) -> (a % n + n) % n 

If angles are within [-180, 180] this also works:

a = targetA - sourceA a += (a>180) ? -360 : (a<-180) ? 360 : 0 

In a more verbose way:

a = targetA - sourceA a -= 360 if a > 180 a += 360 if a < -180 

This gives a signed angle for any angles:

a = targetA - sourceA a = (a + 180) % 360 - 180 

Beware in many languages the modulo operation returns a value with the same sign as the dividend (like C, C++, C#, JavaScript, full list here). This requires a custom mod function like so:

mod = (a, n) -> a - floor(a/n) * n 

Or so:

mod = (a, n) -> (a % n + n) % n 

If angles are within [-180, 180] this also works:

a = targetA - sourceA a += (a>180) ? -360 : (a<-180) ? 360 : 0 

In a more verbose way:

a = targetA - sourceA a -= 360 if a > 180 a += 360 if a < -180 

This gives a signed angle for any angles:

a = targetA - sourceA a = (a + 180) % 360 - 180 

If angles are within [-180, 180] this also works:

a = targetA - sourceA a += (a>180) ? -360 : (a<-180) ? 360 : 0 

In a more verbose way:

a = targetA - sourceA a -= 360 if a > 180 a += 360 if a < -180 

This gives a signed angle for any angles:

a = targetA - sourceA a = (a + 180) % 360 - 180 

Beware in many languages the modulo operation returns a value with the same sign as the dividend (like C, C++, C#, JavaScript, full list here). This requires a custom mod function like so:

mod = (a, n) -> (a % n + n) % n 

If angles are within [-180, 180] this also works:

a = targetA - sourceA a += (a>180) ? -360 : (a<-180) ? 360 : 0 

In a more verbose way:

a = targetA - sourceA a -= 360 if a > 180 a += 360 if a < -180 

This gives a signed angle for any angles:

angle = targetAngle - sourceAngle angle = (angle + 540) % 360 - 180 

If angles are within [-180, 180] this also works:

angle = targetAngle - sourceAngle angle += (angle > 180) ? -360 : ((angle < -180) ? 360 : 0) 

In a more verbose way:

angle = targetAngle - sourceAngle angle -= 360 if angle > 180 angle += 360 if angle < -180 

This gives a signed angle for any angles:

a = targetA - sourceA a = (a + 180) % 360 - 180 

If angles are within [-180, 180] this also works:

a = targetA - sourceA a += (a>180) ? -360 : (a<-180) ? 360 : 0 

In a more verbose way:

a = targetA - sourceA a -= 360 if a > 180 a += 360 if a < -180