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Topic: how to find the points inside a curvature shape
Replies: 3   Last Post: Jan 23, 2013 10:38 PM

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Roger Stafford

Posts: 5,929
Registered: 12/7/04
Re: how to find the points inside a curvature shape
Posted: Jan 23, 2013 1:12 PM
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"Tinith " <> wrote in message <kdp38c$d9g$>...
> Hi, i have a polygon (e.g: rectangle) where it has equally spaced points (co-ordinates are known) inside it. then i need to draw a curvature shape (e.g: clothoid cuve, ellipse) inside this polygon. what i want to achieve is to find the co-ordinates of the points which is covered by the curvature shape.
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If by "shape" you mean the region enclosed by a closed curve, then use the inequality available from the equation of that curve. For an ellipse with equation

A*x^2+B*x*y+C*y^2+D*x+E*y+F = 0

you would test your points with the inequality

sign(A)*(A*x^2+B*x*y+C*y^2+D*x+E*y+F) <= 0

With a clothoid curve (cornu or Euler spiral), which is not a closed curve, I have no idea what it would be that you want. It has no inside or outside, only points along an infinitely thin curve. What would you call its "shape"?

Roger Stafford

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