34 lines
1.2 KiB
Haskell
34 lines
1.2 KiB
Haskell
isOverlapping :: Triangle Double -> Triangle Double -> Bool
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isOverlapping t1 t2 = vertexInside || midLineInside
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where
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vertexInside =
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any (isInside t1) (vertices t2) ||
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any (isInside t2) (vertices t1)
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isInside t = (Outside /=) . overlapping t
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midLineInside =
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any (\p -> isInside t1 p && isInside t2 p) midPoints
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midPoints =
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[ intersections l1 l2 | l1 <- midLines t1
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, l2 <- midLines t2 ]
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intersections (a1,b1,c1) (a2,b2,c2) =
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( -(-b2*c1+b1*c2)/(a2*b1-a1*b2)
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, -(a2*c1-a1*c2)/(a2*b1-a1*b2) )
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midLines (Triangle a b c) =
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[line a b c, line b c a, line c a b]
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line (x,y) (ax, ay) (bx, by) =
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(ay+by-2*y, -ax-bx+2*x, -ay*x-by*x+ax*y+bx*y)
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test = map (uncurry isOverlapping)
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[ (Triangle (0,0) (5,0) (0,5), Triangle (0,0) (5,0) (0,6))
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, (Triangle (0,0) (0,5) (5,0), Triangle (0,0) (0,5) (5,0))
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, (Triangle (0,0) (5,0) (0,5), Triangle (-10,0) (-5,0) (-1,6))
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, (Triangle (0,0) (5,0) (2.5,5), Triangle (0,4) (2.5,-1) (5,4))
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, (Triangle (0,0) (1,1) (0,2), Triangle (2,1) (3,0) (3,2))
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, (Triangle (0,0) (1,1) (0,2), Triangle (2,1) (3,-2) (3,4))
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, (Triangle (0,0) (1,0) (0,1), Triangle (1,0) (2,0) (1,1))]
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