distance-field

A Rust library/executable for generating distance field bitmaps to render as pseudo-vector images in a shader

Documentation

Generator binary

Checkout the repository and cd into it; then run:

cargo run --example generator -- img/input.png output.png 64 64

This will take the following image as input:

And generate a 64x64 distance field:

Now we can use the generated distance field to create a vector image.

Using the distance field

First we need to scale it up with a linear interpolation:

Then we apply a treshold function:

You can see that we have something which looks very similar to the original input image and that just from a 64x64 image! But it's still very pixelated and doesn't look like a vector image. This can be fixed by not doing a hard treshold but allowing some shades of gray.

Library

An example usecase for the library would be to automatically convert asset images. You can achieve this by having a build.rs similar to this:

extern crate image;
extern crate distance_field;

use std::fs::File;
use distance_field::DistanceFieldExt;

fn convert_image_to_dfield(input: &str, output: &str) {
    // Load the 'input' image
    let img = image::open(input).unwrap();

    // Generate a distance field from the image
    let outbuf = img.grayscale().distance_field(distance_field::Options {
        size: (128, 128),
        max_distance: 256,
        ..Default::default()
    });

    // Save it to 'output' as a PNG
    let ref mut fout = File::create(output).unwrap();
    image::ImageLuma8(outbuf).save(fout, image::PNG).unwrap();
}

fn main() {
    convert_image_to_dfield("img/input.png", "output.png");
}

And adding the following to Cargo.toml:

[packages]
build = "build.rs"

[build-dependencies]
image = "0.18"
distance-field = "0.1"