My UVs are consistantly off-center....how to fix during creation?

[Frenetic]

This bothers me…supremely…

I’m trying to make a grassblade-mesh. I start with a plane, 10x100, 10 subdivisions on the long axis, adjust the pivot, do some vertex-manipulation. I DO delete one triangle at the top to make an on-center tip. Check pic:

creation

When I go to AutoUV and use the patch-builder, the UVs are everso slightly off-center. Check the tip of the grassblade:

off-kilter UVs

UV Atlas is funky:

UV Atlas

X Atlas is right on the money but when you accept, the UVs get all ‘fat’…

X Atlas

Fat UVs:

Patch Builder vs X Atlas

vs:

Yes, I can go edit UVs during the model-creation (thanks Epic!) but this is going to bother-me just-knowing it’s off…betting someone out there can relate. Even with manually translating, I couldn’t get it on-center 100% but more to the point: WHY is this happening? Is there a setting I am missing?

I tried to set UVs before editing the mesh, various thresholds/values in the intermediary panels during creating; nothing.

Ultimately this will be used to help drive derived-normals so getting it on-center is more-correct, but also technically-correct, the best kind of correct.

Direction, suggestions??

[Frenetic]

Solved: I had to use a box-projection else it was starting the patchwork from ‘somewhere else’…

[BananableOffense]

It seems like maybe you are following my bezier grass video series? If so I was probably gonna talk about deleting the extra triangle when we got around to the optimization phase which should be soon.

In any case, I just tested this in the modeling tool and my UVs worked as intended. I deleted the extra tri, centered the vert, and then used the auto UV to fix the resulting distortion. The result was pixel perfect.

If you are following the videos, one note about deleting the extra triangle is that the UV coordinates at the tip of the grass will no longer be 0-1 from edge to edge, which does slightly break certain effects like the rim/edge normal, which is based on the 0-1 UV space. It is possible to compensate for this, but if you don’t, things might look a little off at the tip.

[Frenetic]

I’m following someone’s series, if that be ye, then sí, señor, that is the series I am working-from.

I DID just discover this, even with defaults, this is what I get for UVs of a plain plane, seems amiss…

Summary

Of course I manage to muck this up. Going back to fix and fiddle.

[BananableOffense]

Yeah that is me.

And that looks right to me. 0.5 will look much brighter than you’d think it should due to sRGB vs linear color nonsense, but if you put a step node set to 0.5 in there, I should expect it would run right down the middle.

If you remap from sRGB to linear, you get this gradient:

The midpoint now looks properly 50% gray, but if we put a 0.5 step node in we’ll find this:

[Frenetic]

No, the gradient is going the wrong way. Somehow the UVs were rotated, which I didn’t notice/check, until now.

And thanks for the videos.

[BananableOffense]

Ah I see, you’re right, it is backwards. Mine was correct but I was viewing it from the opposite side hah.
It’s mostly irrelevant since the grass blade is generally symmetrical - but yeah probably best to flip it.

Thanks, glad to see they’re reaching the community here.

[Frenetic]

They are indeed getting out to the community. Excellent resources to build from.