Finding distance of imaginary point

Question

I have all coordinates but Px, and I need to find the distance between Px and the Mouse Location(red line). It will be implemented on javascript, any ideas?

http://mathworld.wolfram.com/Point-LineDistance2-Dimensional.html with the assumption you mean perpendicular distance — pvg, Dec 12 '15 at 21:32
yes, also assuming that the mouse can be anywhere else, on both sides of the blue line — fabriciofreitag, Dec 12 '15 at 21:36
answer is listed right in the linked page. scroll down to 'line defined by two points' — pvg, Dec 12 '15 at 21:40

Chris · Accepted Answer · 2015-12-15T11:20:24.680

1

There you go:

var P1 = {x: 10, y: 5},
    P2 = {x: 8,  y: 4},
    PM = {x: 2,  y: 5};

function distance(source, target1, target2) {
    var zaehler = Math.abs((target2.x - target1.x)*(target1.y - source.y) - (target1.x - source.x)*(target2.y - target1.y));
    var nenner = Math.sqrt(Math.pow(target2.x - target1.x, 2) + Math.pow(target2.y - target1.y, 2));
    return zaehler/nenner;
}

console.log(distance(PM, P2, P1) === distance(PM, P1, P2));

edited Dec 15 '15 at 11:20

answered Dec 12 '15 at 21:55

Chris

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I'm confused with distance's parameters, but I think I know what you meant – fabriciofreitag Dec 12 '15 at 22:05
thank you so much, extra small question, can I tell whenever the mouse crosses the blue line? – fabriciofreitag Dec 12 '15 at 22:29
answering my previous question: http://stackoverflow.com/questions/1560492/how-to-tell-whether-a-point-is-to-the-right-or-left-side-of-a-line – fabriciofreitag Dec 12 '15 at 22:37

Finding distance of imaginary point

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