Hello,
Thank you for your answer, it's what I want to get. I want too that the contour of the hole inside has not this effect.

- HoleEffect.png (137.6 KiB) Viewed 4670 times
I tried your correction, but I've got a violation access (I just comment the last AddXYZ line).
Maybe I have a wrong installation because if I don't fill all the points of the series (it means 10x10 points), I have this access violation.
First I've just wanted to add points where the data are valid.

- ViolationAccess.png (21.52 KiB) Viewed 4674 times
I think it should be possible to fill the series with any number of points. So I don't understand this behavior.
My goal is to draw a surface in which there are holes with any number of points.
Nicolas