How to calculate the centre point of a circle given three points?

Question

I am using Javascript and I know the positions of 3 points. I wish to use these to find out the center point of a circle.

I have found this logic (Not the chosen answer

Answer 1

Thanks to @Gaurav Ojha in the comments I found this solution : What is the algorithm for finding the center of a circle from three points?

And changed it to work with Javascript :

function CalculateCircleCenter(A,B,C)
{
    var yDelta_a = B.y - A.y;
    var xDelta_a = B.x - A.x;
    var yDelta_b = C.y - B.y;
    var xDelta_b = C.x - B.x;

    center = [];

    var aSlope = yDelta_a / xDelta_a;
    var bSlope = yDelta_b / xDelta_b;

    center.x = (aSlope*bSlope*(A.y - C.y) + bSlope*(A.x + B.x) - aSlope*(B.x+C.x) )/(2* (bSlope-aSlope) );
    center.y = -1*(center.x - (A.x+B.x)/2)/aSlope +  (A.y+B.y)/2;
    return center;


}

All you need to do is pass it 3 points :

 var threePoints = [{x:1, y: 2},{x:4, y: 4},{x:6, y: 2} ]

console.log(CalculateCircleCenter(threePoints[0],threePoints[1],threePoints[2]))

To get this answer :

[x: 3.5, y: 1.5]

Hope this helps :)