Difference between revisions of "polypoint"

m
m (2D Polygon Collision Detection Function)
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----
 
----
 +
<nowiki>
 
function polyPoint(vertices,px,py)
 
function polyPoint(vertices,px,py)
 
local collision = false
 
local collision = false
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   return collision
 
   return collision
 
end
 
end
 +
</nowiki>
 
----
 
----
  
 
Note: The code assumes your polygon vertices are stored in a table with tuples or pairs of x and y like this.
 
Note: The code assumes your polygon vertices are stored in a table with tuples or pairs of x and y like this.
 
+
<nowiki>
 
v = {}
 
v = {}
 
v[1] = {x = 200,y = 100}
 
v[1] = {x = 200,y = 100}
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v[3] = {x = 350,y = 300}
 
v[3] = {x = 350,y = 300}
 
v[4] = {x = 250,y = 300}
 
v[4] = {x = 250,y = 300}
 +
</nowiki>
  
 
You can find the .love here for an example. Love Version 11.3
 
You can find the .love here for an example. Love Version 11.3
 
[https://love2d.org/forums/download/file.php?id=18245]
 
[https://love2d.org/forums/download/file.php?id=18245]

Revision as of 20:05, 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 end


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]