31 lines
762 B
Lua
31 lines
762 B
Lua
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-- check if something is in the ellipse
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-- we need to define a center point, semi-major axis, and semi-minor axis
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local ellipse = {}
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ellipse.__index = ellipse
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setmetatable(ellipse, {
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__call = function(cls, ...)
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return cls.new(...)
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end,
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})
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function ellipse.new(center_x, center_y, major, minor)
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local self = setmetatable({}, ellipse)
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self.center_x = center_x
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self.center_y = center_y
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self.major2 = major * major
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self.minor2 = minor * minor
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return self
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end
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function ellipse:contains(x, y)
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local x_diff = x - self.center_x
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local y_diff = y - self.center_y
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x_diff = x_diff * x_diff
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y_diff = y_diff * y_diff
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local p = (x_diff / self.major2) + (y_diff / self.minor2)
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return p <= 1
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end
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return ellipse
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