feat: add rings.rs

Cargo.toml

@@ -4,7 +4,6 @@ version = "1.0.0"
 authors = ["Ingolf Wagner <contact@ingolf-wagner.de>"]
 edition = "2018"
 
-
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 description = "Convenience library to use geo to create art."
 documentation = "https://github.com/mrVanDalo/polygon-art"

README.md

@@ -6,7 +6,15 @@ Convenience library to create art using [geo](https://georust.org/).
     * load SVGs
     * scaling
 
-# Asteroids
+# Binaries
+
+I deliver some binaries to give you an impression and ideas
+for your own images. 
+
+All binaries created by polygon art have the same
+command line interface.
+
+## Asteroids
 
 asteroids is an example binary which renders an
 image inspired by the
@@ -14,11 +22,11 @@ image inspired by the
 
 ![image](./images/asteroids.png)
 
-run `asteroids --help` to get information.
-All binaries created by polygon art have the same
-command line interface.
+## Rings
 
-# How to run examples
+![image](./images/rings.png)
+
+# How to run /examples
 
 ```
 cargo run --example clipping -- --help # run the examples/clipping

src/bin/rings.rs

@@ -0,0 +1,55 @@
+use geo::algorithm::rotate::{Rotate, RotatePoint};
+use geo::algorithm::translate::Translate;
+use geo::{polygon, Coordinate, MultiPolygon, Point};
+use geo_clipper::Clipper;
+use polygon_art::{Context, MergeExt, TranslateExt};
+use rand::prelude::StdRng;
+use rand::Rng;
+
+fn main() {
+    let mut context = Context::create();
+    context.translate_center();
+
+    let min = f64::min(context.width, context.height);
+    let number_of_rings = (min / 150.) as i32;
+
+    let mut radius = min / 2. - 5.;
+    for _ in 0..number_of_rings {
+        let ring_size = context.gen_rng().gen_range(10..(radius as i32 / 5)) as f64;
+        radius = radius - ring_size;
+        if radius < 10. {
+            break;
+        }
+        let polygons = generate_ring(&mut context.gen_rng(), radius, ring_size);
+        radius = radius - ring_size;
+        context.draw_multipolygon(&polygons);
+    }
+
+    context.render();
+}
+
+fn generate_ring(rng: &mut StdRng, radius: f64, ring_size: f64) -> MultiPolygon<f64> {
+    let main = polygon![
+    (x: 0.0, y:0.0),
+    (x: ring_size , y:0.0),
+    (x: ring_size , y:ring_size ),
+    (x: 0.0, y:ring_size ),
+    ]
+    .translate_center()
+    .rotate(30.)
+    .translate(0., radius);
+
+    let center_point = Point(Coordinate { x: 0., y: 0. });
+    let parts = rng.gen_range(20..120);
+    let rotation = 360. / parts as f64;
+    let direction = if rng.gen_bool(0.5) { -1. } else { 1. };
+    let fragment = main.difference(
+        &main.rotate_around_point(direction * rotation, center_point),
+        100.,
+    );
+    let mut polygons: MultiPolygon<f64> = MultiPolygon(Vec::new());
+    for index in 0..parts {
+        polygons.merge(&fragment.rotate_around_point(rotation * index as f64, center_point));
+    }
+    polygons
+}