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UnitySDF
Signed Distance Field asset importer for Unity; append +sdff to the end of an image file name.
The image should originally be high resolution, and the unity Import Setting "Max Size" should be used to scale it down.
Generation
This library can automatically convert mask textures to SDFs on import, or can be used manually either in editor or at runtime.
Non-destructive
Append +sdf to the end of a filename to import the file as a signed distance filed. There are several options.
| Postfix | Effect |
|---|---|
| +sdf | Import the image as an SDF file, using the current import settings |
| +sdff | Overwrite the import settings to the recommended Alpha8, and turn off sRGB for 4-channel textures |
| +sdf4 | Perform SDF for each of the 4 channels, not just the alpha channel |
On-Demand or at Runtime
Create an instance of the SDFGenerator ScriptableObject to hold the configuration options you want, or create one at runtime.
In Editor
Fill out the "Targets" list with the textures you want to convert, and press Generate. Each texture will have a duplicate in the same folder with a postfix of ".sdf".
At runtime
Call the Generate method on a SDFGenerator instance. The method will return a an SDF Texture2D.
Usage
An SDF-aware shader is included at Sprites/SDFDisplay. It supports:
- Dilation
- Emboss
- Outline
- Underlay (shadow)
- Face Texturing
Other Info
Internally it uses the Jump Flood Algorithm on GPU to generate the distance fields. The shader "Internal/SDFGenerator" contains the passes required; the first pass calculates the coordinates to the nearest edge and propagates edges outwards, and the second pass calculates distances from those edges.
Common Problems
Sprites become very blurry: Make sure you are using an SDF aware shader.
Drop shadows are cut off: The sprite may need to be larger to account for the inflated size once adding a shadow or large outline.
Image has lost its colour: Do not use +sdff mode, and ensure the Format is something sensible (and not Alpha8).
Edges are wonky: Turn off texture compression; instead reduce the texture size by reducing its resolution, or find a balance of resolution and compression quality.