From 51e5506cd8674a30d515902697833288b35e893e Mon Sep 17 00:00:00 2001
From: Tangent 128 <Tangent128@gmail.com>
Date: Sun, 17 Mar 2019 01:04:03 -0400
Subject: [PATCH] Add linear_gradient() helper

---
 hello_gradient/src/main.rs | 22 ++++++++++------------
 lights/src/rgb.rs          |  4 ++++
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/hello_gradient/src/main.rs b/hello_gradient/src/main.rs
index 49913b5..43978d5 100644
--- a/hello_gradient/src/main.rs
+++ b/hello_gradient/src/main.rs
@@ -1,12 +1,13 @@
 #![no_std]
 #![no_main]
 
+use core::iter::repeat;
 use lights::{
     gamma::GammaCorrector,
     PixelIterator,
     rgb::{
-        blend,
         gray,
+        linear_gradient,
         Rgb
     }
 };
@@ -22,17 +23,14 @@ fn main() -> ! {
     let teal = Rgb(0, 75, 150);
     let purple = Rgb(75, 0, 150);
 
-    let mut gradient = (0..16u8).map(
-        |x| blend(red, yellow, gray(x * 16))
-    ).chain((0..16u8).map(
-        |x| blend(yellow, green, gray(x * 16))
-    )).chain((0..16u8).map(
-        |x| blend(green, teal, gray(x * 16))
-    )).chain((0..16u8).map(
-        |x| blend(teal, purple, gray(x * 16))
-    )).chain((0..16u8).map(
-        |x| blend(purple, red, gray(x * 16))
-    )).cycle();
+    let segment_length = 11;
+
+    let mut gradient = linear_gradient(red, yellow, segment_length)
+        .chain(linear_gradient(yellow, green, segment_length))
+        .chain(linear_gradient(green, teal, segment_length))
+        .chain(linear_gradient(teal, purple, segment_length))
+        .chain(linear_gradient(purple, gray(0), segment_length))
+        .chain(repeat(gray(255)).take(60)).cycle();
 
     loop {
         gradient.clone().take(20).render_to(&mut lights);
diff --git a/lights/src/rgb.rs b/lights/src/rgb.rs
index 2b37c9d..617b83e 100644
--- a/lights/src/rgb.rs
+++ b/lights/src/rgb.rs
@@ -60,3 +60,7 @@ pub const fn gray(gray: u8) -> Rgb {
 pub fn blend(a: Rgb, b: Rgb, mix: Rgb) -> Rgb {
     (a * Rgb(255 - mix.0, 255 - mix.1, 255 - mix.2)) + (b * mix)
 }
+
+pub fn linear_gradient(from: Rgb, to: Rgb, steps: usize) -> impl Iterator<Item = Rgb> + Clone {
+    (0..steps).map(move |x| blend(from, to, gray((x * 255 / steps) as u8)))
+}