No Generation textures where is no UVs

Generation texture coords don’t work in EEVEE and Cycles (baking) if object don’t have UV’s
Bug or feature?

I think that is an old limitation that Tangents will only be correct with UVmap.
I am not sure that what is obtained with Cycles without an UVmap is supposed to be considered correct.

:thinking: I sort of thought that you had to have UV coordinates when working with any textures.

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Cycles: Using the map is fine with or without UVs present, also as a normap map. didn’t try baking. Although, could be the situation where if you load it up again with no UV you get garbage result. Used to apply for node groups with tangent input. Worked fine disconnected, until you loaded it up elsewhere. I don’t know.

Eevee: Using the map is fine without UVs present. Fed through a normal map, it fails.

@ sundialsvc4
I shun UVs like the plague.
UV_Stretch_Why.blend (1.4 MB)
See attached file. This always happens to me when I try to use UV. Why?
This is for driving tangents, so it needs to be absolutely 100% perfect.
I ended up splitting the object into parts; parts where I can avoid UVs, and parts I cannot avoid UVs. Meaning I end up with two materials I need to maintain. Grouping is not an option here due to node wrangler not being able to preview outputs within a group.

But I’m curious, how on earth did I manage to screw up such a simple object/UV?

And yes. I’m aware I can re-do it and it will help. I just fail to spot the reason it turns out the way it does. Also, even with lvl 3 subdiv modifier applied, I still get shading error on the tangent edge when using UV. Devs just told me to increase geometry, 6400 faces for a disk isn’t enough?..

I’m likely failing to grasp exactly what you’re doing here, but at a casual glance, that looks to be an incredibly easy object to unwrap without any stretching.

You’ve got a lot of stretching and odd vertex splits. Geometry is irrelevant, suggestions to subdivide will potentially disguise the problem, but not it’s not a solution. I would guess that, somewhere in the process of rectifying, you’ve introduced a split by using sync selection.
Use the textools rectify operator and debug with a color grid.
Screenshot_2019-08-14_14-14-00

I’m still curious about what he’s trying to do, assuming he’s probably doing something I’m not immediately familiar with. But looking at it from the perspective of a standard unwrap, it seemed more like he was trying to unroll all the faces his cylinder, when all he really needs to do is add 4 seams along that tiny lip to relieve the tension, or just separate that lip entirely, while still keeping the face of his cylinder as its own island.

My process for lathed objects is generally to reset one face, select all and follow active quad. Then move to corner with image bound constrain on. With pivot to 2D cursor, scale all to fill whole UV space. The procedural texture require this format. UV proportions doesn’t matter, I can shift edges around if I need to control texture density (procedurals), since the direction is untouched (for tangent use). I don’t need a seam for this, although I have a seam there for a more normal unwrap (not the additional one on file but a third one not included).

Stretching doesn’t matter for this, but no, I did not notice the vertex splits. I have no idea where those came from.

I don’t know what textool rectify is, but I see now that it would go seriously awry if I tried to pack it. I know I suck at Uv and will never get good at it :smiley: So every time I try, I end up with stretchy issues like this when “everything” (with my bad eyesight) looks perfectly healthy.

Thanks for the help. I would never have figured it out.