Signed Distance Field (SDF) textures can be used to render text or other vector art more flexibly[1], with higher quality while using less video memory (for the texture).

This no_std library renders SDF:s directly and not by downscaling a higher resolution rasters.

[1] For example:

• It is possible to use single a 64px glyph to render both 14px and 200px glyphs.
• It is easy to add glow, outlines and such.

Comparisons:

NOTE: Use fontdue for simple glyphs instead. It is a lot faster.

| Task | SDF | regular | |-----------------------------:|:-------:|:--------:| | High resolution glyphs | ✓ | ✓ | | Medium resolution glyphs | ✓ | ✓ | | Low resolution glyphs | | ✓ | | Stretched or squished glyphs | ✓ | | | Shadows borders and effects | ✓ | | | GUI:s | | ✓ | | 3D game worlds | ✓ | |

• :whitecheckmark: means it is good at

Example usage with image:

```rust let font = fontsdf::Font::from_bytes(..).unwrap();

let (metrics, sdf) = font.rasterize('x', 64.0, true); image::GrayImage::fromraw(metrics.width as _, metrics.height as _, sdf) .unwrap() .save("sdfx.png") .unwrap(); ```

Example output:

Normal

SDF

Example results:

Normal

• 128x156
• 80px font size

SDF

• 128x128
• 48px (+radius) font size (32px input size should be enough for any output size)
• 'free' shadow

TODO:

• dual distance field (https://steamcdn-a.akamaihd.net/apps/valve/2007/SIGGRAPH2007_AlphaTestedMagnification.pdf)