[Q] Texture mapping problem...

[Kyuman]

Hi...

I have another question.
I want to draw a stroke using texture mapping.
I set the texture coordinate just like this figure.
http://home.postech.ac.kr/~misterq/rib_vector.jpg

But I got the result like this.
As you see it, it has an artifact: black parts in the stroke.
http://home.postech.ac.kr/~misterq/mapping.jpg

Please explain what the problem is.
Thank you.