From 1c06343fa64b6c8a4e4b8126456dbc1e5bbc3fd6 Mon Sep 17 00:00:00 2001
From: hut <hut@hut.pm>
Date: Mon, 18 Mar 2024 23:47:03 +0100
Subject: [PATCH] dye stars in their color (doesn't work too well yet)

---
 src/main.rs   |  3 +++
 src/nature.rs | 27 +++++++++++++++++++++++++++
 src/world.rs  |  7 ++++---
 3 files changed, 34 insertions(+), 3 deletions(-)
 create mode 100644 src/nature.rs

diff --git a/src/main.rs b/src/main.rs
index 68e22c7..d9f09e4 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -6,6 +6,9 @@ mod hud;
 mod actor;
 mod starchart;
 
+#[allow(dead_code)]
+mod nature;
+
 use bevy::window::{Window, WindowMode, PrimaryWindow, CursorGrabMode};
 use bevy::diagnostic::FrameTimeDiagnosticsPlugin;
 use bevy::prelude::*;
diff --git a/src/nature.rs b/src/nature.rs
new file mode 100644
index 0000000..bffd1d5
--- /dev/null
+++ b/src/nature.rs
@@ -0,0 +1,27 @@
+// This stuff here, this stuff is messy. Nobody wants to deal with this,
+// nobody cares how it works, but I guess we need it as an ingredient for
+// the universe *sigh* so here we go.
+
+pub fn star_color_index_to_rgb(color_index: f32) -> (f32, f32, f32) {
+    let temperature = 4600.0 * ((1.0 / (0.92 * color_index + 1.7)) + (1.0 / (0.92 * color_index + 0.62)));
+
+    let (red, green, blue) = if temperature <= 6600.0 {
+        let red = 255.0;
+        let green = 99.4708025861 * (temperature / 100.0).ln() - 161.1195681661;
+        let blue = if temperature <= 2000.0 {
+            0.0
+        } else {
+            138.5177312231 * ((temperature / 100.0) - 10.0).ln() - 305.0447927307
+        };
+        (red, green, blue)
+    } else {
+        let red = 329.698727446 * ((temperature / 100.0 - 60.0).powf(-0.1332047592));
+        let green = 288.1221695283 * ((temperature / 100.0 - 60.0).powf(-0.0755148492));
+        let blue = 255.0;
+        (red, green, blue)
+    };
+
+    let clamp = |x: f32| -> f32 { (x / 255.0).max(0.0).min(1.0) };
+
+    return (clamp(red), clamp(green), clamp(blue))
+}
diff --git a/src/world.rs b/src/world.rs
index 6ff3c25..0e5d74d 100644
--- a/src/world.rs
+++ b/src/world.rs
@@ -1,4 +1,4 @@
-use crate::{actor, camera, starchart};
+use crate::{actor, camera, starchart, nature};
 use bevy::prelude::*;
 //use bevy::core_pipeline::Skybox;
 //use bevy::asset::LoadState;
@@ -169,9 +169,10 @@ pub fn setup(
     // Generate starmap
     for star in starchart::STARS {
         let brightness = star[3] * 2000.0;
+        let (r, g, b) = nature::star_color_index_to_rgb(star[4]);
         let star_color_handle = materials.add(StandardMaterial {
-            base_color: Color::rgb(0.0, 0.0, 0.0),
-            emissive: Color::rgb_linear(brightness, 0.9 * brightness, brightness),
+            base_color: Color::rgb(r, g, b),
+            emissive: Color::rgb_linear(r*brightness, g*brightness, b*brightness),
             ..default()
         });
         let dist = 1e6;