Jolt SoftBody 3D Stiffness not working as expected
Tested versions
Reproducible in: v4.7.2.stable.official [ed1daf0bf], v4.7.stable.mono.official [5b4e0cb0f], v4.6.3.stable.official [7d41c59c4], v4.5.stable.official [876b29033]
System information
Godot v4.7.2.stable - Arch Linux #1 SMP PREEMPT_DYNAMIC Mon, 14 Sep 2026 22:41:30 +0000 on Wayland - X11 display driver, Multi-window, 2 monitors - OpenGL 3 (Compatibility) - NVIDIA GeForce RTX 4070 (nvidia; 615.71.09) - AMD Ryzen 7 5800X 8-Core Processor (16 threads) - 31.26 GiB memory - PulseAudio (44100 Hz, Stereo/mono)
Issue description
The "Linear Softness" property in Softbody 3D Jolt Physics is not working properly. Even with value of 1.0 in stiffness, it is acting weirdly.
Godot physics:
https://github.com/user-attachments/assets/ba1cfa2a-9cd3-4634-be9a-c49d8e8b68fb
Jolt physics:
https://github.com/user-attachments/assets/b7639806-8700-4b57-8a90-5f815cfc22db
Steps to reproduce
Place a softbody, change the value os "Linear Stiffness" and compare the two physics engines.
Minimal reproduction project (MRP)
Source: godotengine/godot