hollow | java library and toolset

I have written a WebGL program which displays a rotating cube. The indices are in counter-clockwise order as viewed from the outside. However, when I decide to enable cull faces, the faces that I understand to be "front" are culled, and the cube appears to be hollowed-out. I can fix this issue by telling WebGL to cull "front" faces instead.

I declared the cube's vertex positions, texture coordinates, and indices as follows: image or text.

My question is: am I supposed to declare points in counter-clockwise order as viewed from within the shape? If not, why are the indices I am using backwards?

This program (which is already the minimum reproducible example) is below.

I need to create a chevron style progress bar which I can do with solids but I would like to only have the active step solid and the inactive steps hollow. How can I do this? This is what I have so far. Any ideas how can I accomplish this?

I have an image like this:

after I applied some processings e.g. cv2.Canny(), it looks like this now:

As you can see that the black lines become hollow. I have tried erosion and dilation, but if I do them many times, the 2 entrances will be closed(meaning become connected line or closed contour).

How could I make those lines solid like the below image while keep the 2 entrances not affected?

Update 1

I have tested the following answers with a few of photos, but the code seems customized to only be able to handle this one particular picture. Due to the restriction of SOF, I cannot upload photos larger than 2MB, so I uploaded them into my Microsoft OneDrive folder for your convenience to test.

https://1drv.ms/u/s!Asflam6BEzhjgbIhgkL4rt1NLSjsZg?e=OXXKBK

Update 2

I picked up @fmw42's post as answer as his answer is the most detailed one. It doesn't answer my question but points out the correct way to process maze which is my ultimate goal. I like his approach of answering questions, firstly tells you what each step should do so that you have a clear idea about how to do the task, then provide the full code example from beginning to end. Very helpful.

Due to the limitation of SOF, I can only pick up one answer. If multiple answers are allowed, I would also pick up Shamshirsaz.Navid's answer. His answer not only points to the correct direction to solve the issue, but also the explanation with visualization really works well for me~! I guess it works equally well for all people who are trying to understand why each line of code is needed. Also he follows up my questions in comments, this makes the SOF a bit interactive :)

The Threshold track bar in Ann Zen's answer is also a very useful tip for people to quickly find out a optimal value.

I am trying to write a method that accepts 3 Paraments, and return a hollow square.

1st Method parameter = length of string. 2nd Method parameter = how many characters would be there in the one arm of the square. 3rd Method parameter = String.

Condition: Example if 2nd parameter is 4 so total 12 characters required to form a square, if given string is sorter the that then it will be repeated (abcdefghabcd).

I have written a code but that is not satisfying few conditions.

I want to be able to rename keys in an array of objects. I know how to do them manually, one by one. But what I want to do is rename the keys from another object.

My data:

i want to create hollow square with function in javascript.

this my code

This returned to me as a string:

I'm new in learning XPath and XSLT, so I need some help with one task.

I need to transform this XML using XSLT:

I'm learning Java and I'm currently trying to make some ASCII art with the program. I was able to make a hollow diamond, but I'm struggling with creating a "checkerboard" or square pattern. I'm trying to create something that looks like this: