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55 lines
1.6 KiB
55 lines
1.6 KiB
use plotters::prelude::*;
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fn snowflake_iter(points: &[(f64, f64)]) -> Vec<(f64, f64)> {
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let mut ret = vec![];
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for i in 0..points.len() {
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let (start, end) = (points[i], points[(i + 1) % points.len()]);
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let t = ((end.0 - start.0) / 3.0, (end.1 - start.1) / 3.0);
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let s = (
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t.0 * 0.5 - t.1 * (0.75f64).sqrt(),
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t.1 * 0.5 + (0.75f64).sqrt() * t.0,
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);
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ret.push(start);
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ret.push((start.0 + t.0, start.1 + t.1));
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ret.push((start.0 + t.0 + s.0, start.1 + t.1 + s.1));
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ret.push((start.0 + t.0 * 2.0, start.1 + t.1 * 2.0));
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}
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ret
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}
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fn main() -> Result<(), Box<dyn std::error::Error>> {
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let root =
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BitMapBackend::new("plotters-doc-data/snowflake.png", (1024, 768)).into_drawing_area();
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root.fill(&WHITE)?;
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let mut chart = ChartBuilder::on(&root)
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.caption("Koch's Snowflake", ("sans-serif", 50))
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.build_cartesian_2d(-2.0..2.0, -1.5..1.5)?;
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let mut snowflake_vertices = {
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let mut current: Vec<(f64, f64)> = vec![
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(0.0, 1.0),
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((3.0f64).sqrt() / 2.0, -0.5),
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(-(3.0f64).sqrt() / 2.0, -0.5),
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];
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for _ in 0..6 {
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current = snowflake_iter(¤t[..]);
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}
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current
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};
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chart.draw_series(std::iter::once(Polygon::new(
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snowflake_vertices.clone(),
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&RED.mix(0.2),
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)))?;
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snowflake_vertices.push(snowflake_vertices[0]);
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chart.draw_series(std::iter::once(PathElement::new(snowflake_vertices, &RED)))?;
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Ok(())
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}
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#[test]
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fn entry_point() {
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main().unwrap()
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}
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