How to link four points to a convex polygon? I mean how to identify the order of these four points.
Thanks.
Zhong
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How to link four points to a convex polygon? I mean how to identify the order of these four points.
Thanks.
Zhong
The atan2() method is handy for this, and is found in most languages.
atan2(y,x)and converts rectangular coordinates(x,y)to the anglethetafrom the polar coordinates(r,theta).Given 4 points, find their average. Then calculate the four (x,y) vectors obtained by subtracting the average from each of the four points.
For each of these (x,y) vectors, calculate the angle θ = atan2(y,x). θ will be between -π/2 and π/2.
Sort the θ’s. This will give you the order of the points, in clockwise order.
This only works for convex quadrilaterals.