Difference between revisions of "polypoint"
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Revision as of 20:01, 20 May 2020
Polygon Point Collision Detection
here is the original love2d forum thread: [1]
here is the original source website, beware its written in C++ [2]
The code below is a function that is called to return true when a point is within the vertices of a polygon and false otherwise. The math used is the Jordan Curve Theorem --> [3]
function polyPoint(vertices,px,py) local collision = false local next = 1
for current = 1, #vertices do next = current + 1 if (next > #vertices) then next = 1 end local vc = vertices[current] local vn = vertices[next] if (((vc.y >= py and vn.y < py) or (vc.y < py and vn.y >= py)) and (px < (vn.x-vc.x)*(py-vc.y) / (vn.y-vc.y)+vc.x)) then collision = not(collision) end end return collision
Note: The code assumes your polygon vertices are stored in a table with tuples or pairs of x and y like this.
v = {} v[1] = {x = 200,y = 100} v[2] = {x = 400,y = 130} v[3] = {x = 350,y = 300} v[4] = {x = 250,y = 300}
You can find the .love here for an example. Love Version 11.3 [4]