godotengine / godotengine/godot

Strange culling issue/ mesh appears inside out

Open
#100,155 6 comments 0 reactions 0 assignees View on GitHub
bug needs testing topic:3d topic:animation
Dominant language
C++
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PR merge metrics
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Description

### Tested versions

4.4 dev6

### System information

Godot v4.4.dev6 - Windows 10.0.22631 - Multi-window, 1 monitor - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 4060 (NVIDIA; 32.0.15.6614) - 12th Gen Intel(R) Core(TM) i5-12400F (12 threads)

### Issue description

I've been racking my brains regarding a strange face culling issue I'm having. I'm using a model that has asymmetrical parts and the meshes on one side display a culling issue, with the front faces being culled, despite the normals being set (and recalculated) correctly in Blender

the meshes that appear on the right appear correctly culled
![Image](https://github.com/user-attachments/assets/3f9c0c97-fe2b-43ed-b3fc-bd681a764c74)

but on the left side they're not
![Image](https://github.com/user-attachments/assets/74f57dc3-2fe3-482f-a47d-51844cea0584)

The modeler doesn't know what could be causing it but assumes it's a shader bug in Godot.

### Steps to reproduce

project attached with model displaying the behaviour. Normals have been checked in Blender

### Minimal reproduction project (MRP)

[culling_issue_project.zip](https://github.com/user-attachments/files/18049801/culling_issue_project.zip)

Contributor guide

Open the contributing guide

Research direction

Start by opening the attached culling_issue_project.zip in Godot 4.4.dev6 and reproducing the asymmetrical mesh behavior described in the issue. Compare the correctly culled right-side meshes with the incorrectly culled left-side meshes, then verify whether the result is tied to the imported model, normals, or Godot's rendering path; done means the cause is identified and the culling behavior is corrected or clearly documented.

Written by the indexing model from the issue text.

Assessment

Tech stack
blender, godot
Domain
computer-graphics, game-dev
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
30/100

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