I have two normalized angles (between 0 and 360 degrees) and i want to find the shortest turn direction from point a to point b. (clockwise or counterclockwise). a or b can be anywhere on the circle, so the function should work in both way: if a is smaller and if a is larger than b.
I am wrote the following function, which works fine except when the shortest distance crosses the 0 degree mark:
function clockwise(a, b){
return a < b;
}
The function return true if it is clockwise and false if the direction is counterclockwise.
How can I get this to work for distances that cross the 0 degree angle? I am looking for an implementation specifically in JavaScript, since I wasn't able to translate any of the mathematical explanations I found. Thanks in advance!
CodePudding user response：
Relative to point a,
- Is clockwise, If b is present is in the next 180
- anticlockwise otherwise
function clockwise(a, b){
let theta1 = b-a;
return theta1 >= 0 && theta1 <= 180; // return true if clockwise
}
CodePudding user response：
There's probably a more elegant solution, but I think this gives the expected results?
(if a=60, b=230 the difference is 170 and clockwise=true is correct..?!)
function clockwise(a, b) {
let clockwise, diff
if (b > a) {
diff = b - a
clockwise = diff >= 0 && diff <= 180
} else {
diff = a - b
clockwise = diff >= 180
}
return clockwise
}
console.log(clockwise(60,230)) // true
console.log(clockwise(220,150)) // false
console.log(clockwise(40,300)) // false
console.log(clockwise(120,214)) // true