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Why do we need reset XForm at all ?

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Message 1 of 3
alex.motion
763 Views, 2 Replies

Why do we need reset XForm at all ?

Hi ! 

 

I thought when mesh gets scaled with scale icon it never changes vertex positions behind a curtain 

thought it just scales object visually and object vertex position numbers stays same , that would explain why scaling is fast and why we need to apply XForm after scaling, but then I just checked scaled object vertices with polyOp.getVert $  command and saw that vertex positions changed .

 

Well, if it changes vertex position float numbers during the scaling, why do we need XForm at all? 

2 REPLIES 2
Message 2 of 3
jon.bell
in reply to: alex.motion

Hi Fantom,

 

Thanks for your question! This may be legacy behavior, but scaling an object at the "root" level instead of the sub-object level (vertices, polys) has been shown to cause geometry discrepancies later on, especially when adding more Editing modifiers to the object stack (or especially when parenting and rotating said objects to others in the scene). Non-uniform scaling can (sometimes) be even worse.

 

In general, it's always better to apply an Xform modifier to your objects and use that to scale them. However, I'll post your question to our devs to see if they can give you a more technical explanation of what's happening here "under the hood." Thanks!



Jon A. Bell
Senior Technical Support Specialist, 3ds Max
Message 3 of 3
alex.motion
in reply to: jon.bell

Hello John ! Thank you for response .

 

I know it spoils modifiers , scaling is multiplication matrix and it applies for whole object 

but it looks like that matrix stays with that object after scaling and it also affects everything after scaling 

 

in other words, what is the difference between scaled 10meter object and created 10 meter object from technical point of view ? I think that xform stuff might be avoided and taken from max at last ...

 

but I need to understand the reason behind it  

as I said, logically I thought that's because vertices positions floats are not affected while scaling , and maybe it's done for  performance reasons to make high poly object scale faster , but it looks like they are updating 

and if they are updating why do we need xform modifier and reset xform utility at all ..

 

"I'll post your question to our devs to see if they can give you a more technical explanation of what's happening here "under the hood." Really hope on that. Thanks! 

 

P.S.

 

If you remember we were also touched that topic about texture paths 

Please Don't forget to mention that one also , about texture file paths saving (now it happens only on max exit, and max crash/abruption makes that paths lost) I think way better is to save it when max saves file. 

 

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