Bruneton's Improved Atmospheric Scattering for Unity

A physically-based atmospheric skybox shader for Unity. Based on work by Eric Bruneton and Scrawk.

How to Install

The core-utils package uses the scoped registry feature to import dependent packages. Please add the following sections to the package manifest file (Packages/manifest.json).

To the scopedRegistries section:

{
  "name": "DSS",
  "url": "https://registry.npmjs.com",
  "scopes": [ "com.dss" ]
}

To the dependencies section:

"com.dss.atmosphere": "1.0.2"

After changes, the manifest file should look like below:

{
  "scopedRegistries": [
    {
      "name": "DSS",
      "url": "https://registry.npmjs.com",
      "scopes": [ "com.dss" ]
    }
  ],
  "dependencies": {
    "com.dss.atmosphere": "1.0.2",
    ...

How to Use

Please see the readme in the package directory for usage information.

Results

Credit

This is an extension of scrawk's implementation of ebruneton's improved atmospheric scattering paper.

Scrawk's Unity port, while excellent, was restricted in many ways due to various hardcoded parameters. As he himself noted:

The demo uses a image effect shader as a example of how to use the scattering. The sphere rendered and its light shafts are hard coded into the shader as its just a example. Some work would be needed to convert this into a practical implementation

This is my attempt at a practical implementation. The result is a tool that generates a single material that you can use as a skybox directly.

Goals

• To modify the existing codebase as little as possible.
• To enable previewing of the atmosphere in the editor.
• To remove the hardcoded sphere, and image-effect rendering assumptions.
• To enable better control over when / how the scattering textures get precomputed and saved.

What I changed

• Added AtmosphereEditorWindow.cs, an editor window to easily generate the required textures.
• Added Atmosphere.shader, a skybox shader to use the generated textures.