Project Curve on surface doing weird!

[chappo]

Hey all,

When projecting a simple nurbs circle primitive on a simple nurbs cylinder primitive the circle tends to break up in 2 parts after the 'project curve on surface' .

I've reset all the settings and still it breaks up the circle in 2 halves.
I can't seem to attach them together neither...

Someone know why this strange 'bug' occures ?

[joojaa]

The curve cant go over the seam so it nust be in two parts!

[chappo]

no no, the curve is still inside the cylinder and doesnt stick out.

a small test i just did is i created a nurbs cylinder and projected a circle onto that and it worked !

BUT , if i rotate the cylinder 90 degrees so its horizontal , the circle tends to break up in 2 parts.

Any idea why it doesn't work after a simple rotation ?

P.s. i project it in top view so it should work !

[joojaa]

Yes exactly when you rotate it 90 dgrees you project the curve over the seam of the cylinder (wich is where it starts), wich causes the projection to split into two parts. Move the seam!

[chappo]

hmmm.....just discoverd something again.
Only 1 projected curve is good while the other breaks up.

I uploaded a picture to clearify a few things.
The first pic is standard.
Simple cylinder, simple curve.. projection ... et voila.... both sides are selectable without any break ups

Second pic is also standard but cylinder is rotated -90 degrees.
The projected curve on the top/ bottom (depends if you rotated 90 or -90) breaks up in 2 halves....why ??
Seeing that the other pic works fine !

http://www.brandendzand.nl/temp/curves.jpg

[joojaa]

Well you are NOT listening. Id expect that to happen!

OK lets draw this out for you! Think of it thisway the cylinedr is a flat piece of paper thats rolled into a tube! now if you project a circle on this piece of paper and you arent fgoing across the seam then you get two circle (close enough) but if you project over the seam then the other circle will lie on the edge of the paper thus the other side or the circle is on the other end of the paper and tho ther is at the other!

Except now the parameter range jumps from 1 to 0! Intead of being real paper! Causing breakup! Nothing exactly new under the sun! Move the seam to anotherplace!

Any quetions?

[joojaa]

To analyze your picture the seam lies on the axis that is pointing in the right lower corner of the pic. And lies underneath whan you rotate!!

[chappo]

Hmm....i wish i could delete this whole thread for posting a very very stupid question

I know understand what you meant and tried a few things....and yeah....it was the seam that got in the way of everything.

I guess i thought the cylinder was a solid object and so assumed there was something strange going on.

Thank you again for helping out.. i'll go pick a nice flat wall now to bang my head a bit on it to straight things out in my head

[joojaa]

I could delete this thread if you so wish, id rather not because now someone else might get it too!

But yeah you can move the seam around in a paramorisized surface if you wish!

[chappo]

yeah... leave it as it is
Someone else might benefit from it.

Thank you again for your help !

[joojaa]

Ok if you realy realy need a curve over the seam do this!

Use the move seam function to move the seam somewhere else! Project, the move the projection away a bit in the opposite direction of the seam. Then move the seam back and move the curve back to its original place its now one curve over the seam!

PS if you go into shaded mode you can see in wich w