Heyhey!
When I make a model, I usually do 1 model where I don´t apply the subsurf, do the UV Seams, and unwrap, and I do 1 model where I apply the subsurf using the same UV Seams.
And it usually works great! the UV Seams stay exactly where you would expect them to, like this:
But while making these toothpaste Containers, i noticed the UV Seam shifts (the red line goes up)after I apply the subsurf, as you can see in the following image:
My question is: why is this happening here(or why did it never happen before) and how to make it, so the uv seam stays where you would more "expect it to" when I apply subsurf...
Thank you in advance!
I usually do only 1 set of texture materials for both the "lowpoly" and "highpoly" version, and it worked great until the UV Seam shifted like here
SubD usually stretched and shifts the seam like that if you're not careful.
Found the post where Martin goes into it, turns out the explanation was for you:
https://cgcookie.mavenseed.com/community/18177-questions-regarding-the-pull-or-pinch
I guess the SubD doesn't "care" where your UV Seam is, so much like any geometry, it might get pushed around, if nothing is constraining it or holding it, which in this case, could be a support loop.(hope i got that right)
Adding the support loop DOES sharpen the edge though, is there no way to tell the SubD Modifier "hey here´s a UV Seam, don`t move that"?
That didn't fix it, none of the options did... unfortunately.
Pinning the UVs also didn*t help :(
Hi @nougat time ,
| "is there no way to tell the SubD Modifier "hey here´s a UV Seam, don`t move that"?
No, you are right, that Edge Loops can only be constraint by 'Holding Edges'. How far away those 'Holding Edges' are, influences how far the original Edge Loop can move around; which also means, how much smoothing is done by the Subdivision Surface algorithm, or how sharp the Edge loop becomes...I'd recommend using two 'Holding Edges' one on each side and if possibly evenly spaced...again: how far away from the (in your case) Seam, decides how much or little smoothing will happen.
Not moving the Edge Loop at all, also means not smoothing it and therefore it stays as sharp as without the Subsurf. (it doesn't sharpen it; it already was that sharp...)
Basically, what you are asking for, is that the Seam doesn't move, but still gets smoothed, which sounds like a contradiction to me.
I think I see what you´re saying, the shift of the uv seam is nothing more than the smoothing of the geometry itself, and how far it shifts depends on how even /close the surrounding geometry/loops are.
And if you really don´t want the uv to shift at all, you can´t use subdivision surface, cuz that´s what it does, it subdivies and evens it.
Thinking back the cases where it magically worked, I either had relatively evenly laid out geometry, or really close constraining loops...
Well I feel a bit smarter now, thank you Omar and Martin!
