Bug: 3MF crash when read file

[tungpv90]

Describe the bug

1. Some 3MF file crash when ReadFile
   Error in File ..3MF/XmlSerializer.cpp line 430:

mesh->mTextureCoords[0] = new aiVector3D[group->mTex2dCoords.size()];
Replace:
mesh->mTextureCoords[0] = new aiVector3D[mesh->mNumVertices];

2. 3MF can't load Embedded Texture or export embedded texture to glb file
   3d.zip

[kimkulling]

The texture coordinates are not stored correctly. The meshes are having more than 30000 vertices, but we are only assigning 16000 texture coordinates. SO it crashes.

This is an Assimp bug.

[tungpv90]

Source code of 3MF is too old. i think you need update it @kimkulling

[kimkulling]

Which source-code do you mean? The source you can find in the library is the assimp-code. There is no newer code.

But I have a better understanding what is going wrong: the texture-coordinates are injected via resource groups. In the face-definition the referenced textures are descriped via their index in the resource group. And this is currently wrong. The current implementation of the 3mf-parser just copies the texture coordinates into the mesh which holds the faces.

[tungpv90]

Thanks for answering
i read 3MF_Core_Specification and 3MF Materials Extension
https://github.com/3MFConsortium/spec_core/blob/master/3MF%20Core%20Specification.md
https://github.com/3MFConsortium/spec_materials/blob/master/3MF%20Materials%20Extension.md

some properties like colorgroup... have not been updated yet.
I've been trying to learn and try the code but it seems I still haven't been successful.

[tungpv90]

thank you updated this bug.
But when i convert 3mf to glb. i can't load embedded texture
This is image in Microsoft powerpoint 2019

and this is in my app

2_3mf.zip

[kimkulling]

Hm, seems to be an issue with the embedded texture support in 3MF. I will need to take another look onto that!

[SamuelTallet]

Hello @kimkulling and @tungpv90,

Bug is still here on current master branch.

assimp info t-rex.3mf (when it works) sees 1 embedded texture. Just an hypothesis... but does embedded thumbnail is erroneously counted as texture?

assimp extract t-rex.3mf fails to export embedded texture (0 byte output).

Would it be possible to use integer as texture reference, like for other formats? For instance:
*0
instead of:
*/3D/Texture/755688691_2048x2048.png

t-rex.3mf.zip

[galdenny]

Hello,

Would it be possible to skip loading the textures? I wanted to post the same bug before I found this one. But to be honest, in some applications the stored textures are not relevant.
Can you please create a flag to skip loading some parts?

Thank you in advance.