CODEWITHSUNDEEP
javascriptmath
Jimi Alvaro
Jimi Alvaro

Reputation: 73

Get coordinate by length between two points

I am drawing on canvas and I want to get a point by length between two other points. I have:

let uno = {x:100, y:200};
let dos = {x: 900, y:2000};
let length = 20; //px

How can I get point between uno and dos by distance in pixels length (starting from uno)? Example image in the

attachment

Upvotes: 5

Views: 1160

Answers (3)

ibrahim mahrir
ibrahim mahrir

Reputation: 31692

function getCoordinateByLength(point1, point2, length){
    var dx = point2.x - point1.x;
    var dy = point2.y - point1.y;
    var distance = Math.sqrt(dx * dx + dy * dy);
    if(distance == 0)
        return {x: point1.x, y: point1.y};

    var rx = point1.x + (point2.x - point1.x) * length / distance;
    var ry = point1.y + (point2.y - point1.y) * length / distance;
    return {x: rx, y: ry};
}

Upvotes: 5

Giladd
Giladd

Reputation: 1389

Using trigonometry:

function lenpoint(x1, y1, x2, y2, len) {
  var dx = x2-x1, 
      dy = y2-y1;
  var theta = Math.atan2(dy, dx);
  var xp = len * Math.cos(theta), 
      yp = len * Math.sin(theta);
  return [xp + x1, yp + y1];
}

Upvotes: 8

RyanZim
RyanZim

Reputation: 6994

Try this:

let uno = {x:100, y:200};
let dos = {x: 900, y:2000};
let length = 20; //px

let point = {
  x: findPoint(length, uno.x, dos.x),
  y: findPoint(length, uno.y, dos.y),
}

console.log(point);

function findPoint(d, a, b) {
  return d * (b - a) + a;
}

Based on https://math.stackexchange.com/a/1625335; haven't tested this myself.

Upvotes: 0

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