Why doesn't Max remember my UV's? [Solved]

CodeferBlue

So I have an object. I'm done working with this object in Edit Poly. So I add an Unwrap UV modifier on top. As I'm unwrapping the object I notice I've made a mistake in the mesh. I don't go back to the edit poly modifier, I instead add an edit poly modifier on top of the unwrap uv modifier. Correct my mistakes. Then, to go back to unwrapping the object, I add an unwrap on top of the edit poly but the objects UV's reset. Max just forgets that I've edited the UV's.

Is this a bug or am I missing something here?

final_fight

UVs may get destroyed depending how much mesh topology changes.

CodeferBlue

Well. I'm talking a vertex movement. A polygon delete. Nothing big at all. And the UV's aren't destroyed. They're completely reset.

final_fight

Doesn't happen to me in 3ds Max 2017. Why first Unwrap modifier looks like it was instanced?

musashidan

Just collapse the first unwrap(which is an instance)to bake the UVs, edit topo, apply unwrap again.

kanga

musashidan said:

Just collapse the first unwrap(which is an instance)to bake the UVs, edit topo, apply unwrap again.

+1

Mark Dygert

The modifier stack is dependent on what is below, even a minor change can upset things up the stack. This becomes doubly important if a higher modifier is based on selection, which happens if you had some faces selected and applied modifier. Like if you did a soft select and then applied a noise modifier it would only effect those verts, which is helpful, but not if you go back down the stack and do something.

Let me back up... 

Each vert/face gets a number and quite a few modifiers that deal with sub-object components are relying on that numbering. If you change one vert or face the entire model could be assigned it's numbering. What was vert 222 is now vert 6 and everything that was happening to vert 222 is NOT transferred to vert 6, it happens to vert 222 wherever it is. BUT if you collapse the stack and make your edits, that renumbering happens after the UV edits and all is saved.

When you collapse your stack it writes that data into the object and saves it. Which is why you can collapse and then go on to make geometry edits. The history is set in stone and any new edits treat it like it was historical fact that couldn't be changed. 

Selection vs object modification can get a little confusing especially when there are so many modifiers that operate on the sub-object level. But get in the habit of collapsing your stack, like other people suggested.

Even if you correctly exited the sub-object level when you first applied it, if you go back and select faces and then don't exit, it can start treating it like it was a selection based edit and mess up your stack. Some of them have a toggle button for selection and object, but a lot of them don't.

A geometry edit down the stack, will certainly mess up any modifiers that are dependent on selection.

When you have a stack, it is a live editing of the objects history. If you travel back in time (down the stack) and step on a butterfly, that small step could have large repercussions, like killing all of the dinosaurs, ha!

Like others have suggested, it is very wise to "save/bake" your UV's into the objects history, by collapsing the stack.

YannickStoot

perna said:

When someone uses the Edit Poly modifier it almost always means they misunderstand or at least mis-use the stack, so I would suggest thinking through your workflow here.

The purpose of the stack is to be a parametric modeler, not to serve as "editable history" or to hold "backup versions" of your mesh. Unfortunately there are widespread misunderstandings regarding this. If you don't want to commit changes because you are, say, exploring design choices, simply create copies of your object or use Save Incremental.

Neither Edit Poly nor Unwrap UVW are parametric, so their existence on the stack, unless you're doing something crazy/experimental, should only be temporary; Add Unwrap UVW, do your work in it, collapse it. It's not supposed to stay on the stack. It modifies parallel, not serial data, which is why users have long requested that UVW editing should happen on the same root level as XYZ editing.

Yesss! Finally someone who gets it! +1

CodeferBlue

Ah Okay understood. Thanks @musashidan for a simple, to the point explanation and thanks everybody else for enlightening me on why this actually occures and how the modifier stack works. Much appreciated. I'll just experiment a little with the modifier stack to figure out my self on what are good and bad habits when working with the modifier stack.

One thing sort of concerns me however. @perna stated that "The purpose of the stack is to be a parametric modeler, not to serve as "editable history" or to hold "backup versions" of your mesh.". I've found some people that use the stack with the intention of it being an editable history. I've watched tutorials where people have made edits using edit poly after the unwrap modifier and in their case, Max remembered their UV's exactly the way they edited them. Collapsing the modifier was not required by them. Why is that? What could they have possibly done differently?

Thanks again.

Mark Dygert

CodeferBlue said:

I've watched tutorials where people have made edits using edit poly after the unwrap modifier and in their case, Max remembered their UV's exactly the way they edited them. Collapsing the modifier was not required by them. Why is that? What could they have possibly done differently?

The stack is evaluated from the bottom up. If you toss an edit poly modifier on top of the unwrap modifier, it will respect the uvs. If you go back down the stack under the unwrap modifier and start messing around, you run the risk of messing up your UV's. 

You can keep tossing modifiers on top of each other but at that point you're building a complex stack that could blow up in your face. At best it will slow down to a crawl as it stops to evaluate everything from the bottom up. There really isn't much of a point of keeping a long stack if you can't go back down and make edits. It's best to collapse it and speed things up. 

The stack wasn't originally invented for poly modeling, not like what we do today. It was originally intended for applying things like bend, taper, noise and other types of object level modifiers.

The editable polygon object wasn't added until max4 and Edit Poly didn't become a modifier until Max7. Even still they are duct taped on with fractured features across 4 object types and 4 different modifiers.

Poly Object, Editable Mesh, Editable Poly, Edit Poly, Edit Mesh. So much redundancy and overlap in all of those separate groups of tools and all because people needed more than what was originally planned.

If they where to build max from the ground up, the customization would probably look a lot more like Modo and KeyHydra. Unwrap would probably be a mode not a modifier and the stack would probably be a node based editing tool like Houdini.