Point in Polygon algorithm giving wrong results for negative points

Question

I am trying to check if the lat,lon is in the polygon or not. Here is my array :

$vertices_x : 
Array
(
    [0] => -32.581189
    [1] => -38.785885
    [2         


        

Answer 1

I don't think your point (173.5385,-34.472) is in the polygon.

Your x value is much larger than the largest x vertex. You can see this if you plot it. You can see from the orange point that even if you just have your lat/long mixed up it's still not in the polygon.

EDIT:

Upon first inspection of your new polygon and point it looks as though this one is more likely to be contained within the polygon (x_min < x < x_max and y_min < y < y_max).

-36.236432, 176.467563
-37.936530, 172.688266
-39.801068, 177.895786
-35.345287,-177.446011
-34.625208,-177.907437 

point:

(-37.0278,176.6158)

However, plotting this again reveals that the point is outside the polygon:

... and zooming in ...

---

I plotted these in python with matplotlib and I recommend you do something similar when debugging this type of thing. If you want to stay with php, html, etc., you could use svg polygons or html canvas instead.