# Re: is it possible to adjust convex hull to draw blue line instead of green line?

```On Saturday, September 17, 2016 at 9:35:35 AM UTC+8, Steve D'Aprano wrote:
> On Sat, 17 Sep 2016 10:20 am, meInvent bbird wrote:
>
> > i succeed to use code to draw green line, but green line not draw the
> > large area, expect second uploaded picture, the blue line connect
> > the bottom of red line graph
>
>
> Please don't waste our time with dead code that has been commented out or
> that doesn't do anything.
>
> Here is your code with the commented out dead code removed. You should do
> this, don't expect us to do it:
>
>
> im = img.copy()
> cntcounter = 0
> for cnt in contours:
>             print("approx=" + str(approx))
>             cntcounter = cntcounter + 1
>             print("here1")
>             hull = cv2.convexHull(cnt,returnPoints = True)
>             print("here2")
>             while im is None:
>                 # WARNING: THIS IS AN INFINITE LOOP
>                 time.sleep(1)
>             if im is not None:
>                 print("here3")
>                 previousx = 0
>                 previousy = 0
>                 for c in hull:
>                     if (previousx != 0 and previousy != 0 and c[0][0] != 0
>                         and c[0][1] != 0 and abs(previousy - c[0][1]) > 10
>                         and abs(c[0][0] - previousx) > 1
>                         ):
>                         while im is None:
>                             # WARNING: THIS IS AN INFINITE LOOP
>                             time.sleep(1)
>                         cv2.line(im, (previousx, previousy),
>                                  (c[0][0], c[0][1]), (0, 255, 0), 2)
>                         print("")
>                     previousx = c[0][0]
>                     previousy = c[0][1]
>
>
>
>
> Now it is much easier to read without the noise.
>
> Problems:
>
> (1) img is not defined;
>
> (2) approx is not defined;
>
> (3) contours is not defined;
>
> (4) cv2 is not defined;
>
> (5) you have TWO possible infinite loops in your code;
>
> (6) time is not defined, but this at least I can guess is the
>     standard time module;
>
> (7) c is not defined.
>
>
> As given to us, we cannot run your code or understand it, because too many
> things are undefined.
>
> My **guess** is that cv2.line() will take an argument to set the line
> colour. You should read the documentation for cv2.line().
>
>
>
> http://sscce.org/
>
>
>
>
>
>
> --
> Steve
> “Cheer up,” they said, “things could be worse.” So I cheered up, and sure
> enough, things got worse.```
```
sorry for assuming all have experience in this kind of application

here is my code

https://gist.github.com/hoyeunglee/0165b24b10de0baf8538e8866e2dcd60