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TressFX for Godot

Real-time hair and fur for Godot 4.7, ported from AMD TressFX 4.1 as a native GDExtension. This guide explains how to install the addon, bring in a hairstyle, make it collide with a character, tune it, and keep it fast.

Page	What it covers
Getting Started	Install, project settings, your first hair, colliders, the editor
Hair from Blender	Grooming hair in Blender, exporting it, setting it up in Godot
Assets	The .tfx, .tfxbone and .tfxmesh formats and how to produce them
Nodes	Every property and method of TressFXHair, TressFXCollisionMesh, TressFXStats
Tuning	What the simulation parameters do, recipes for fur, long hair and ponytails, fixing jitter
Performance	What costs what, measured numbers, LOD, shadows, memory
Troubleshooting	Nothing shows up, hair explodes, hair goes through the body, editor issues
Building	Building the extension from source, CI, code layout

Requirements

• Godot 4.7 or later.
• The Forward+ or Mobile renderer. The Compatibility renderer has no RenderingDevice and cannot run the compute shaders.
• A GPU with Vulkan, Direct3D 12 or Metal support (anything that runs Forward+).
• No special project settings; TAA is recommended (see Getting Started).

How it works, in one paragraph

A hairstyle is a set of guide strands, each a chain of 4 to 64 vertices. Every frame a compute shader moves the guide vertices: it applies gravity and wind, pulls each strand back towards its authored shape, keeps every segment at its rest length, and copies the motion of the skeleton bone the strand is attached to. Colliders are turned into a signed distance field (a 3D grid of "how far from the surface am I") and any vertex that ends up inside is pushed out. Around each guide strand a few follow strands are placed as offset copies, which is where the visual density comes from. Finally every strand is drawn as a thin camera-facing ribbon whose width is expanded to at least a pixel, with a lighting model made for fibers.