Difference between revisions of "polypoint"
m (2D Polygon Collision Detection Function) |
m (2D Polygon Collision Detection Function) |
||
Line 10: | Line 10: | ||
The math used is the Jordan Curve Theorem --> [https://en.wikipedia.org/wiki/Jordan_curve_theorem] | The math used is the Jordan Curve Theorem --> [https://en.wikipedia.org/wiki/Jordan_curve_theorem] | ||
− | + | [code] | |
− | + | function polyPoint(vertices,px,py) | |
− | function polyPoint(vertices,px,py) | + | local collision = false |
− | local collision = false | + | local next = 1 |
− | local next = 1 | ||
for current = 1, #vertices do | for current = 1, #vertices do | ||
next = current + 1 | next = current + 1 | ||
Line 28: | Line 27: | ||
end | end | ||
return collision | return collision | ||
− | end | + | end |
− | + | [/code] | |
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. | ||
− | v = {} | + | [code] |
− | v[1] = {x = 200,y = 100} | + | v = {} |
− | v[2] = {x = 400,y = 130} | + | v[1] = {x = 200,y = 100} |
− | v[3] = {x = 350,y = 300} | + | v[2] = {x = 400,y = 130} |
− | v[4] = {x = 250,y = 300} | + | v[3] = {x = 350,y = 300} |
− | + | v[4] = {x = 250,y = 300} | |
− | + | [/code] | |
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 20:26, 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]
[code]
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
[/code]
Note: The code assumes your polygon vertices are stored in a table with tuples or pairs of x and y like this.
[code]
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}
[/code]
You can find the .love here for an example. Love Version 11.3 [4]