Lock Y world position in UV Layout

[JDee]

I feel that I'm digging not in the right direction here...
Is there a way to transfer (lock) Y world position onto UV Layout fora simple mesh that is being unwrapped as a strip, perhaps that is doable as a postprocess.
That looks like Projection Offset  in UV Layout should do the trick but that doesnt work for me. (red box what is needed as a uv output)

[davpe]

hey, i'm not sitting in front of houdini right now, but you should be able to do that easily. after you use the uv layout SOP, use vertex wrangle or vertex VOP to copy the original v@uv.y from the node before the uv layout, keeping v@uv.x unaffected.

[JDee]

1 hour ago, davpe said:

hey, i'm not sitting in front of houdini right now, but you should be able to do that easily. after you use the uv layout SOP, use vertex wrangle or vertex VOP to copy the original v@uv.y from the node before the uv layout, keeping v@uv.x unaffected.

not sure what you mean by copying the original since theres no 'correct' y uv available
can you have a look at example when you get a min. thanks
UV_Y.hip

Edited February 14, 2022 by JDee

[davpe]

aha i see. check the example file if that's what u want. if you needed a completely procedural approach, it would be slightly more complicated to setup, but definitely possible too.

right now i just created a group "extrudeSide" on polyextrude2 SOP, and then UV_transform SOP to offset the selection.

UV_Y_reply.hip

[JDee]

I need actually a fully procedural, that box is a very simplified example
imagine it as a building with different levels etc.
I'm looking to how to transfer Y world position to uv space ? kinda lock it by Y while unrapping as a strip layout
better reference

Edited February 14, 2022 by JDee

[davpe]

well in that case that wouldn't be about simply locking it, as the building may be 100 units, but uv space operates in 0-1 range. 

so it depends a) do u want to keep it proportional? b.) do you want to fit it in the 0-1 range, or u dont mind if it goes across uv tiles? c) are u dealing with just a single asset, or u need to keep consistent scale across multiple buildings? d) are u modeling it in houdini too, or it comes from somewhere else?having things modeled in houdini would make things much easier as you can prepare things in advance in the modeling stage.

[davpe]

but anyways, in wrangle you can always do:

v@uv.y = @P.y;

this will literally take position Y coordinate and replaces the uv Y coordinate by it. if thats what u want.

[JDee]

thanks. good questions.

I'm actually unwrapping a low poly buildings (no windows or other facade small details) sooo:
b. yes  0-1 range only one tile
a. thats the thing, simply v@uv.y = @P.y; makes it unproportional by Y so it actually takes the real world height and applies it to uv space while it keeps X locked
d. external geo not modeled in houdini

so at this point I cant get an idea how to measure the scale and keep it consistent

 

UV_Y_obj.hip

bldng.obj

Edited February 14, 2022 by JDee

[Aizatulin]

Hi,

you can also use relbbox(@P).y instead of @P.y to make it 0-1. After this you can use fit function.

UV_Y_obj_mod.hipnc