HTML5 / js - how to animate straight line between two coordinates?

Question

Simple enough question (could be wrong)

im looking to animate between two points in a straight line, using HTML5 and/or Jquery.

ctx.beginPath();
ctx.mov         


        

Answer 1

You could use a linear interpolation or lerp. Something like this. Here is an example on jsfiddle: http://jsfiddle.net/UtmTh/ and here is the main code:

var canvas = $("#paper")[0];
var c = canvas.getContext("2d");

var startX = 50;
var startY = 50;
var endX = 100;
var endY = 100;
var amount = 0;
setInterval(function() {
    amount += 0.05; // change to alter duration
    if (amount > 1) amount = 1;
    c.clearRect(0, 0, canvas.width, canvas.height);
    c.strokeStyle = "black";
    c.moveTo(startX, startY);
    // lerp : a  + (b - a) * f
    c.lineTo(startX + (endX - startX) * amount, 
             startY + (endY - startY) * amount);
    c.stroke();
}, 30);​