poly2cw doesn't work for this simple rectangle. I have an example here. Could you please check this code?

Question

Kaveh Gharibi 2016-8-9

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评论： Kaveh Gharibi 2016-8-9

Xs{1}=[
     0
     1
     1
     1
     0
     1]
Ys{1}=[1.0000
    1.0000
    0.0101
         0
         0
    0.5000]
[xr,yr]=poly2cw( Xs{1}   , Ys{1}    )
for i=1:length(xr)
plot(xr(i),yr(i),'or')
hold on
drawnow
pause
end

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Answer 1

Sean de Wolski 2016-8-9

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https://ww2.mathworks.cn/matlabcentral/answers/298938-poly2cw-doesn-t-work-for-this-simple-rectangle-i-have-an-example-here-could-you-please-check-this#answer_231290

编辑：Sean de Wolski 2016-8-9

在 MATLAB Online 中打开

EDIT with more info from comments

It sounds like what you really want is the convex hull of your points since your points, ordered like they are now, do not create a rectangle.

dt = delaunayTriangulation(xr,yr);
hullidx = convexHull(dt);
xa = xr(hullidx);
ya = yr(hullidx);
[xa,ya] = poly2cw(xa,ya);
comet(xa,ya)

If you don't want the convex hull but do want to encourage your shape to be close to convex, then look at alphaShape which will also do a triangulation for you but will allow concavities below a certain size based on alpha.

Original

It starts in the upper left hand corner at (0,1) and moves to (1,1) and then down to (1,0) before completing the triangle. This is indeed clockwise

comet(xr,yr)

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Sean de Wolski 2016-8-9

See Edit

Kaveh Gharibi 2016-8-9

Thank you! That actually works great! Since the geometry is changing in my code in each time step, the geometry is not convex always and I think can use alphashape as you said or boundry.

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Answer 2

KSSV 2016-8-9

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https://ww2.mathworks.cn/matlabcentral/answers/298938-poly2cw-doesn-t-work-for-this-simple-rectangle-i-have-an-example-here-could-you-please-check-this#answer_231238

在 MATLAB Online 中打开

Xs=[ 0
     1
     1
     1
     0
     1] ;
Ys=[1.0000
    1.0000
    0.0101
         0
         0
    0.5000] ;
[xr,yr]=poly2cw( Xs,Ys) ;
plot(xr,yr)

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Kaveh Gharibi 2016-8-9

编辑：Kaveh Gharibi 2016-8-9

Thank you for response. But, maybe I was not clear. If you look at the results in the loop, you will see that the polygone is not clockwise. If you run the code you shared here, it will give you this plot below. This is not a clockwise polygon

Kaveh Gharibi 2016-8-9