Moving a Point Along a Line in JavaScript Canvas

Question

Let\'s say that I have the coordinates of a line (25,35 45,65, 30,85 - It would be a two part line). I need to move a point (car) along that line at a constant distance ever

Answer 1

8 years too late but someone may find this useful. This method is far faster given it doesn't uses stuff like atan, cos, sin and square root of which all are slow.

function getPositionAlongTheLine(x1, y1, x2, y2, percentage) {
    return {x : x1 * (1.0 - percentage) + x2 * percentage, y : y1 * (1.0 - percentage) + y2 * percentage};
}

Pass percentage as value between 0 and 1 where 0 is start of the line and 1 being the end.

var xy = getPositionAlongTheLine(100, 200, 500, 666, 0.5);
console.log(xy.x, xy.y);