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JavaScript implementation of winding number algorithm to determine whether a point is inside a polygon
//JavaScript implementation of winding number algorithm to determine whether a point is inside a polygon
//Based on C++ implementation of wn_PnPoly() published on http://geomalgorithms.com/a03-_inclusion.html
function pointInPolygon(point, vs) {
var x = parseFloat(point[0]), y = parseFloat(point[1]);
var wn = 0;
for (var i = 0, j = vs.length - 1; i < vs.length; j = i++) {
var xi = parseFloat(vs[i][0]), yi = parseFloat(vs[i][1]);
var xj = parseFloat(vs[j][0]), yj = parseFloat(vs[j][1]);
if (yj <= y) {
if (yi > y) {
if (isLeft([xj, yj], [xi, yi], [x,y]) > 0) {
wn++;
}
}
} else {
if (yi <= y) {
if (isLeft([xj, yj], [xi, yi], [x, y]) < 0) {
wn--;
}
}
}
}
return wn != 0;
};
function isLeft(P0, P1, P2)
{
var res = ( (P1[0] - P0[0]) * (P2[1] - P0[1])
- (P2[0] - P0[0]) * (P1[1] - P0[1]) );
return res;
}
@shakedlokits

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@shakedlokits shakedlokits commented Apr 18, 2019

You are awesome :)

@SebaMederos

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@SebaMederos SebaMederos commented Sep 7, 2020

Can you tell me how to use it please!?

@thejambi

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@thejambi thejambi commented Oct 25, 2020

You are awesome! I needed this magic :)

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