domigome/com.unity.demoteam.mesh-to-sdf

A light and fast real-time SDF generator, primarily for animated characters. The dynamic SDF can be used for all sorts of VFX. Also enables hair-to-character collisions in the new hair package.

Package: com.unity.demoteam.mesh-to-sdf

A real-time Signed Distance Field generator. Use a Mesh or a dynamically deforming SkinnedMesh as input to generate a 3D SDF texture every frame.

The SDF can be used by the VFX Graph, the Hair system, and other effects relying on SDFs.

The generator is real-time - to achieve better performance, it sacrifices robustness and the ability to handle large meshes. Typical resolutions would be a 5-8k triangle mesh in a 16^3-64^3 voxel volume. If your mesh is much larger or messy (holes, spiky shapes, etc.), it's best to use a cleaner low-res proxy mesh instead. Note that the SDF generator shipping with the VFX Graph has a more robust handling of larger or messy meshes, but it's slower.

The generator works by first splatting distances into voxels in a small area around each triangle, then using either a linear flood or jump flood to fill the rest of the volume.

Performance

Tested with a 32^3 voxel volume, 5k triangle mesh

• jump flood: RTX3090 0.22ms
• linear flood, 8 iterations: RTX3090 0.18ms, RTX2080Super 0.21ms

Requirements

• Unity 2021.2+ (mesh buffer access in compute shaders)
• Compute shaders supported on target platform

Installation

Use Add package from git URL (in the Package Manager):

https://github.com/Unity-Technologies/com.unity.demoteam.mesh-to-sdf.git

or

Declare the package as a git dependency in Packages/manifest.json:

"dependencies": {
    "com.unity.demoteam.mesh-to-sdf": "https://github.com/Unity-Technologies/com.unity.demoteam.mesh-to-sdf.git",
    ...
}

Documentation

Quickstart

Examples

Samples included with the package show basic setup and are described in the doc above.

The mesh-to-sdf examples project is a vfx demo, with the dynamic SDFs driving VFX Graph effects and a raymarching shader:

mesh-to-sdf.mov

Acknowledgements

The core functionality of the generator (initial splatting of distances around mesh faces) uses the implementation from TressFX published by AMD under the MIT license. Thank you!

Known issues

Limitations and known issues