Mask geometry edge

[AndresFHO]

Hi everyone. I need to know how to acess to the geometry edges. Let say I have a cylinder without cap at the top or bottom and I need to mask the edge. I know that there is the UV border but this will mask the vertical seem that cuts the side of the cylinder, so I was wondering if there is any other method to mask the edge of the geometry only. 
Thanks a lot!

[Cyril Dellenbach · Accepted solution]

Hello @AndresFHO,

Thanks for the question.

The options I see are: 

1. Use the Polygon Fill tool to select only the faces at the border. This will obviously only work if you have edge loops at the border of the mesh.

2. Make sure the UV shell fill its tile, then use the UV Border generator. This way, it shouldn't consider the vertical seam.

3. Use the UV border, add a paint effect, switch his blending mode to Sub, and paint the vertical seam to erase it. This solution isn't very versatile, but sometimes you don't have many other choices.

4. My last solution would be to simply paint the Border in the 2D View while holding the shift key to make straight lines. Not the best one, I agree.

On a side note, this won't work with an empty cylinder, but depending on the mesh, the baked maps could help to select the borders.

I hope this will be useful.

Best regards,

[AndresFHO]

Hi Cyril, thank you for your reply and sorry for the late response.
My particular case it's a bit more complicated than the cylinder but the theory is just the same. 
This is my shape, it's an skirt. I want to select only the edges and iterate over them, but, I would like to be able to manage this in a more procedural way because I need to create an smart material from this to be reused in several assets

So here is my mesh with the edges selected, now, I use UV Border Distance in multiply

As you can see the seam its is still visible, so it means that I have to go and paint by hand. 
I guess that since you gave me several methods and most imply that I have to paint by hand it means that it's not possible to achieve this in the way I need it, it's that right?
Thank you for you help

[Cyril Dellenbach]

Hmmm, you could use two Position generators. The generator will add a vertical gradient and by turning the contrast parameter to 1, you'll be able to use the balance to chose where the mask starts/ends.

But this solution will probably bring many other issues when used on other projects than the skirt.

Unfortunately no, I can't think of another solution to your issue in Substance 3D Painter (if someone does, please let us know).

Best regards,

[AndresFHO]

Thank you for your reply Cyril.
Yeah, since the edge isn't flat I think position won't do the trick. 
Also, I'm trying to use this smart material in other cloth pieces and for example in a shirt, the seams are located in the armhole so it won't work, that's I was expecting of some "generator" that could read only the open faces. 
Thanks again for your time

[davescm]

Another alternative, if the skirt is modelled to have interior and exterior surfaces along with an edge, is to bake a curvature map (make sure it has high enough resolution) and set a generator (mask editor) to pick up only the skirt edges where inside meets outside. Then use global blur in the mask editor to control the distance away from the edges that the mask reaches.

There is a caveat though - the UV islands have to be sufficiently spaced so that the global blur does not extend to an adjacent island.

Dave

[Cyril Dellenbach]

Nicely thought, I think that's best solution. You'll have to add some geometry, but except if you're really aiming for optimisation, I don't think that will be an issue.

Thanks Dave.

[AndresFHO]

Thanks a lot for your reply Dave. 
It kinda works but it doesn't seems to work with the lower edge

I don't know if it might have something to do with the edge not being straight. I can see the bleed you were talking if the 2 UV islands are too close, that wouldn't be a problem to solve I think but yeah, sadly, I cannot make it work with the lower edge.
Thank you for your time