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Ray-casting algorithm: Difference between revisions
→{{header|Lua}}: added Lua solution
m (→{{header|REXX}}: added/changed whitespace and comments, simplified code.) |
(→{{header|Lua}}: added Lua solution) |
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rand = Int(Rnd(0)*(hiNum-loNum+1)+loNum)
End Function </lang>
=={{header|Lua}}==
<lang lua>function Point(x,y) return {x=x, y=y} end
function Polygon(name, points)
local function contains(self, p)
local odd, eps = false, 1e-9
local function rayseg(p, a, b)
if a.y > b.y then a, b = b, a end
if p.y == a.y or p.y == b.y then p.y = p.y + eps end
if p.y < a.y or p.y > b.y or p.x > math.max(a.x, b.x) then return false end
if p.x < math.min(a.x, b.x) then return true end
local red = a.x == b.x and math.huge or (b.y-a.y)/(b.x-a.x)
local blu = a.x == p.x and math.huge or (p.y-a.y)/(p.x-a.x)
return blu >= red
end
for i, a in ipairs(self.points) do
local b = self.points[i%#self.points+1]
if rayseg(p, a, b) then odd = not odd end
end
return odd
end
return {name=name, points=points, contains=contains}
end
polygons = {
Polygon("square", { Point(0,0), Point(10,0), Point(10,10), Point(0,10) }),
Polygon("squarehole", { Point(0,0), Point(10,0), Point(10,10), Point(0,10), Point(2.5,2.5), Point(7.5,2.5), Point(7.5,7.5), Point(2.5,7.5) }),
Polygon("strange", { Point(0,0), Point(2.5,2.5), Point(0, 10), Point(2.5,7.5), Point(7.5,7.5), Point(10,10), Point(10,0), Point(2.5,2.5) }),
Polygon("hexagon", { Point(3,0), Point(7,0), Point(10,5), Point(7,10), Point(3,10), Point(0,5) })
}
points = { Point(5,5), Point(5,8), Point(-10,5), Point(0,5), Point(10,5), Point(8,5), Point(10,10) }
for _,poly in ipairs(polygons) do
print("Does '"..poly.name.."' contain the point..")
for _,pt in ipairs(points) do
print(string.format(" (%3.f, %2.f)? %s", pt.x, pt.y, tostring(poly:contains(pt))))
end
print()
end</lang>
{{out}}
<pre>Does 'square' contain..
( 5, 5)? true
( 5, 8)? true
(-10, 5)? false
( 0, 5)? false
( 10, 5)? true
( 8, 5)? true
( 10, 10)? false
Does 'squarehole' contain..
( 5, 5)? false
( 5, 8)? true
(-10, 5)? false
( 0, 5)? false
( 10, 5)? true
( 8, 5)? true
( 10, 10)? false
Does 'strange' contain..
( 5, 5)? true
( 5, 8)? false
(-10, 5)? false
( 0, 5)? false
( 10, 5)? true
( 8, 5)? true
( 10, 10)? false
Does 'hexagon' contain..
( 5, 5)? true
( 5, 8)? true
(-10, 5)? false
( 0, 5)? false
( 10, 5)? true
( 8, 5)? true
( 10, 10)? false</pre>
=={{header|Nim}}==
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