godotengine / godotengine/godot

`GPUParticlesCollisionSDF3D` does not seem to have any visible effect on particles

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#93,573 6 comments 0 reactions 0 assignees View on GitHub
bug topic:editor topic:rendering
Dominant language
C++
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Description

### Tested versions

v4.2.2.stable.mono.official [15073afe3]

### System information

Godot v4.2.2.stable.mono - Windows 10.0.22631 - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 4080 (NVIDIA; 32.0.15.5599) - AMD Ryzen 9 7950X3D 16-Core Processor (32 Threads)

### Issue description

I have two identical particle systems. Both are set up to have collision mode rigid. Both particle systems are above a cube with which they are supposed to collide. The left particle system interacts with a `GPUParticlesCollisionBox3D` which shows some tunneling issues as identified in https://github.com/godotengine/godot/issues/93570. The right particle system is supposed to interact with a `GPUParticlesCollisionSDF3D`. This is set up to calculate an SDF for a box with the same extents as the `GPUParticlesCollisionBox3D` on the left side. However, no matter which resolution is baked, the particles just go right through the `GPUParticlesCollisionBox3D`. This problem persists even if I double the thickness of the geometry. Also the AABB is set up correctly so it's not an instance of https://github.com/godotengine/godot/issues/93567 :

https://github.com/godotengine/godot/assets/327257/ce0be673-e66b-41e5-8e55-73129812e8ad

### Steps to reproduce

In the attached reproducer project, open `particle_collisions_test3.tscn` to inspect and play around with the setup.

### Minimal reproduction project (MRP)

[reproducer3.zip](https://github.com/user-attachments/files/15961444/reproducer3.zip)

Contributor guide

Open the contributing guide

Research direction

Open the attached reproducer project and inspect particle_collisions_test3.tscn, then run the two particle systems described in the issue. Compare the GPUParticlesCollisionSDF3D setup with the GPUParticlesCollisionBox3D setup across the stated SDF resolutions and geometry thicknesses; done means the SDF collision visibly affects the particles as expected.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp, 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
35/100

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