Initial commit

src/main.rs

@@ -0,0 +1,111 @@
+//#![feature(portable_simd)]
+
+use std::path::PathBuf;
+use clap::{Arg, Parser};
+use image::{GrayImage, ImageBuffer, Luma};
+use image::buffer::ConvertBuffer;
+use rayon::iter::ParallelIterator;
+
+mod transform;
+
+#[derive(Parser)]
+pub struct Args {
+    #[clap(short, long, default_value_t = 3840)]
+    pub width: u32,
+    #[clap(short, long, default_value_t = 2160)]
+    pub height: u32,
+
+    #[clap(short, long, default_value_t = 100)]
+    pub maxiter: usize,
+
+    #[clap(short, long, default_value="out.png")]
+    pub output: PathBuf,
+
+    pub transform: Vec<String>
+}
+
+type Float = f32;
+type Point = Complex<Float>;
+use num::complex::Complex;
+pub type Transform = [(Point, Point); 3];
+
+trait ComplexExt<T> {
+    fn norm2(self) -> T;
+}
+
+impl ComplexExt<Float> for Complex<Float> {
+    fn norm2(self) -> Float {
+        self.im * self.im + self.re * self.re
+    }
+}
+
+fn transform_point(transform: &Transform, point: Point) -> (Point, Point) {
+    let start = transform[0].0 * point.re + transform[1].0 * point.im + transform[2].0;
+    let delta = transform[0].1 * point.re + transform[1].1 * point.im + transform[2].1;
+    (start, delta)
+}
+
+pub struct Config {
+    pub transform: Transform,
+    pub width: u32,
+    pub height: u32,
+    pub maxiter: usize,
+    // We represent escape as the square of its magnitude
+}
+
+
+
+impl Config {
+    fn render_point(&self, (base, delta): (Point, Point)) -> f32 {
+        const ESCAPE: Float = 2.;
+        const ESCAPE2: Float = ESCAPE * ESCAPE;
+
+        let mut base = base;
+        let result  =
+            std::iter::successors(Some(base), |i| Some(*i * *i + delta))
+                .take(self.maxiter)
+                .enumerate()
+                .skip_while(|(_, i)| i.norm2() <= ESCAPE2)
+                .next()
+                .map_or(0.,
+                        |(iter, val)|
+                            iter as Float + 1. - val.norm().ln().ln() / ESCAPE.ln()
+                            );
+        result as f32
+    }
+}
+
+fn main() -> anyhow::Result<()> {
+
+    // let transform = [
+    //     (Point::new(0., 0.), Point::new(1., 0.)),
+    //     (Point::new(0., 0.), Point::new(0., 1.)),
+    //     (Point::new(0., 0.), Point::new(0., 0.)),
+    // ];
+
+    let args = <Args as clap::Parser>::parse();
+
+    let config = Config {
+        transform: transform::parse_transforms(args.transform.iter())?,
+        width: args.width,
+        height: args.height,
+        maxiter: args.maxiter,
+    };
+
+    let scale = 2.0 / std::cmp::min(config.width, config.height) as Float;
+
+    let mut img = ImageBuffer::<image::Luma<f32>, _>::from_par_fn(config.width, config.height, |x, y| {
+        let x = (x as Float) * scale - 1.;
+        let y = (y as Float) * scale - 1.;
+        let point = transform_point(&config.transform, Complex::new(x, y));
+        image::Luma([config.render_point(point)])
+    });
+    let img_norm = img.pixels()
+        .map(|p: &Luma<f32>| p.0[0])
+        .reduce(f32::max)
+        .unwrap_or(1.);
+    img.par_pixels_mut().for_each(|Luma([p])| *p /= img_norm);
+    let img: GrayImage = img.convert();
+    img.save(&args.output)?;
+    Ok(())
+}