add Image::poly

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "fimg"
-version = "0.4.9"
+version = "0.4.10"
 authors = ["bend-n <bend.n@outlook.com>"]
 license = "MIT"
 edition = "2021"

src/drawing/poly.rs

@@ -1,6 +1,7 @@
 //! draw polygons
 use std::{
     cmp::{max, min},
+    f32::consts::TAU,
     ops::DerefMut,
 };
 
@@ -83,4 +84,62 @@ impl<T: DerefMut<Target = [u8]>, const CHANNELS: usize> Image<T, CHANNELS> {
     ) {
         self.points(&[a, b, c, d, a], col);
     }
+
+    /// Draws a regular convex polygon with a specified number of sides, a radius, and a rotation (radians).
+    /// Calls into [`Image::tri`] and [`Image::quad`].
+    /// ```
+    /// # use fimg::Image;
+    /// let mut i = Image::alloc(300, 300);
+    /// //          draw a enneagon
+    /// // at  x150, y150    │  unrotated   white
+    /// // with a radius of ─┼──╮      │      │
+    /// i.poly((150., 150.), 9, 100.0, 0.0, [255]);
+    /// # assert_eq!(i.buffer(), include_bytes!("../../tdata/enneagon.imgbuf"));
+    /// ```
+    pub fn poly(
+        &mut self,
+        (x, y): (f32, f32),
+        sides: usize,
+        radius: f32,
+        rotation: f32,
+        c: [u8; CHANNELS],
+    ) {
+        let trans = |a: f32| (a.cos() * radius, a.sin() * radius);
+        let r = |(a, b): (f32, f32)| (a.round() as i32, b.round() as i32);
+        let add = |(a, b)| (a + x, b + y);
+        match sides {
+            3 => {
+                let space = TAU / 3.0;
+                self.tri(
+                    add(trans(space + rotation)),
+                    add(trans(rotation)),
+                    add(trans(space * 2.0 + rotation)),
+                    c,
+                );
+            }
+            _ => {
+                let space = TAU / sides as f32;
+                for i in (0..sides - 1).step_by(2).map(|i| i as f32) {
+                    self.quad(
+                        r((x, y)),
+                        r(add(trans(space * i + rotation))),
+                        r(add(trans(space * (i + 1.) + rotation))),
+                        r(add(trans(space * (i + 2.) + rotation))),
+                        c,
+                    );
+                }
+
+                if sides % 2 != 0 && sides > 4 {
+                    let i = (sides - 1) as f32;
+                    // the missing piece
+                    self.tri(
+                        (x, y),
+                        add(trans(space * i + rotation)),
+                        add(trans(space * (i + 1.) + rotation)),
+                        c,
+                    );
+                }
+            }
+        }
+    }
 }

src/drawing/tri.rs

@@ -8,9 +8,13 @@ impl<T: DerefMut<Target = [u8]>, const CHANNELS: usize> Image<T, CHANNELS> {
     /// ```
     /// # use fimg::*;
     /// let mut a = Image::alloc(10, 10);
-    /// // draw a triangle from point a v   point b v    point c v
-    /// //                                               with color white
-    /// a.as_mut().tri((3.0, 2.0), (8.0, 7.0), (1.0, 8.0), [255]);
+    /// // draw a triangle
+    /// a.as_mut().tri(
+    ///   (3.0, 2.0), // point a
+    ///   (8.0, 7.0), // point b
+    ///   (1.0, 8.0), // point c
+    ///   [255] // white
+    /// );
     /// # assert_eq!(a.buffer(), b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00");
     /// ```
     pub fn tri(