Votes
1
Product:
3DXchange 6
Version:
6.42
Status:
Assigned
Issue 385
Changing UV Settings / Importing UV Settings for CC Meshes Distorts The CC Mesh
The following bug seems to apply only to CC meshes and a few G6 meshes (such as hair). I did not notice it with G3 or G5 meshes.

Here is how to reproduce the bug using only 3DXChange (i.e. without using any 3rd party software):

1. Load a CC character with clothing into 3DXChange (e.g. CC character with the basic CC dress).
2. Use the 3DXChange UV Settings section to modify the UV Settings for any CC mesh of the loaded character. (e.g. change the UV Type for the CC dress mesh)
3. This will cause the CC mesh to completely distort.

Note: Changing UV settings should never change the mesh shape since UV settings are definitions of how a flat texture map is displayed over the 3D mesh. Thus no matter what the UV settings are changed to (even if completely wrong), the "color" of the mesh may be really odd but the shape of the mesh should remain unchanged.

The above steps demonstrate the bug in the easiest manner but the above process in not very practical. Typically UV mappings would be modified outside of 3DXChange and re-imported. The following steps demonstrate the (same?) bug when importing modified meshes:

1. Load a CC character with clothing into 3DXChange (e.g. CC character with the basic CC dress).
2. Select a CC mesh (e.g. the CC dress mesh) and use the 3DXChange export mesh option in the Replace Mesh section to export the mesh.
3. Use a 3rd party editing tool to modify the exported mesh including a change to the mesh's UV mapping.
4. Replace the original CC mesh with the modified mesh by using the 3DXChange replace option in the the Replace Mesh section.
5. During the import option, ensure that the "Origianl UVs" option is unchecked (to apply the new UV mappings).
6. This will cause the CC mesh to completely distort.

When this issue was first identified (and put in the Issues List), someone reported that they were able to import UV changes made in 3D Studio Max without distortion. I cannot confirm this since I don't have 3D Studio Max but I tried a number of programs (including Anim8or, Hexagon 2.5 and a couple of format conversion programs) and was not able to properly import modified UVs for CC meshes. Since the problem seems to be present even when not using any 3rd party editing software (see the first set of steps above), it seems to me that the bug is related to 3DXChange. Either the person using 3D Studio Max did not properly re-produce my steps or it is possible that the file format produce by 3D Studio Max has some tiny difference which causes 3DXChange to import properly.

However, since the problem occurs even when no third party software is involved and it occurs with multiple software packages when 3rd party software is involved, the fact that 3D Studio Max output works correctly with 3DXChange may be the exception to the rule.

This was observed in Windows 8.1 and 10.
OS: Windows 10
Attachment:
  • Bug - UV Distortion.png
  •  2
  •  4729
Bug
Submitted byLord Ashes
1
COMMENTS (2)
Bellatrix 
Windows7
IClone, 3DX6, CC 6.4.1.

Issue confirmed on CC Natalie and CC Actor Essential Clothed 04 (Girl with corset top + checked skirt)

CLUE IDENTIFIED, using ZBrush
Specifically - the clue lies in external tool EXPORT SETTING step.

Steps
- CC Natalie dress/ CC Ess04 Mini Skirt sent to ZBrush, Import setting default as per normal
- Re-UV
- OBJ Export setting: with TRI + TXR = 3DX issue reproduced (Replace Mesh with Original UV UNCHECKED = mesh mangled)

HOWEVER, if...
- OBJ Export setting: with TRI + TXR + *MRG* = 3DX will import re-UV mesh correctly, with new UV loaded as expected

Do note:
G6 Mason shirt with OBJ export TRI + TXR, will also import re-UV mesh correctly, with new UV loaded as expected
Same for G5 standard character clothing, all work as expected.
No *MRG* (Merging UV Coordinates) required at export stage for G6 or G5 Replaced meshes in 3DX.
Therefore
CC OBJ - 3DX relationship is unique and INCONSISTENT compared to RL standard predecessors.

For whatever reasons, CC OBJ needs an EXTRA STEP of MERGE UV COORDINATE(MRG) at export stage
This is at least true in ZBrush workflow.

It is unclear at this stage, if my discovery is a "fix", or just "culprit identified".
Let us know either way.

IMPORTANT
Please ensure, in the coming CC PIPELINE 1.5 - External Modeling/UV tool import export process, this issue will not be repeated.
Lord Ashes 
It seems the distortion can be caused by other things other than changing UV settings or possibly there is a similar bug caused by something else.

I was able to create a OBJ file which, when imported into 3DXChange as its own item, shows up perfectly fine. However, when the Replace Mesh option is used to replace Natalie's Dress with this file (which has been padded to the correct number of vertices and faces so that it would be compatible) the mesh gets distorted. With this file, the distortion occurred regardless if the "Original UVs" was selected or not (although it seemed that the distortion changed depending if the "Original UVs" was checked or not).

The file was created by taking Natalie's Dress and cutting it down into a vest (i.e keeping only the chest area) and then adding, into the OBJ file, additional v, vn, vt and f entries to match that of the original Dress file. It should be noted that while the Replace Mesh error message indicated that the number of vertices must be the same, I have found that, at a minimum, the number of vertices and faces need to be the same.
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