问题
I want to get angle between 3 points in JavaScript. If I have points A(x1,y1), B(x2, y2), C(x3, y3) I want to get angle that is formed with lines AB and BC.
let A = {x:x1, y:y1}, B = {x:x2, y:y2}, C = {x:x3, y:y3}
回答1:
Try this function :
/*
* Calculates the angle ABC (in radians)
*
* A first point, ex: {x: 0, y: 0}
* C second point
* B center point
*/
function find_angle(A,B,C) {
var AB = Math.sqrt(Math.pow(B.x-A.x,2)+ Math.pow(B.y-A.y,2));
var BC = Math.sqrt(Math.pow(B.x-C.x,2)+ Math.pow(B.y-C.y,2));
var AC = Math.sqrt(Math.pow(C.x-A.x,2)+ Math.pow(C.y-A.y,2));
return Math.acos((BC*BC+AB*AB-AC*AC)/(2*BC*AB));
}
来源：https://stackoverflow.com/questions/17763392/how-to-calculate-in-javascript-angle-between-3-points