From faa2ce4d55508ec4844aed18b5e95821d3f856bf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois?= <mockersf@gmail.com>
Date: Sun, 3 Mar 2024 22:36:11 +0100
Subject: [PATCH] fix example lightmaps after color migration (#12265)

# Objective

- Since #12163 example lightmaps is more dull
<img width="1280" alt="Screenshot 2024-03-02 at 23 04 36"
src="https://github.com/bevyengine/bevy/assets/8672791/7736f420-b9c5-4870-93f6-b5b992c4768a">


## Solution

- Use a srgba color, as it was before:

https://github.com/bevyengine/bevy/blob/b24ab2e9fba5b81aba15da97b6551a4e99aad40c/examples/3d/lightmaps.rs#L39

https://github.com/bevyengine/bevy/blob/b24ab2e9fba5b81aba15da97b6551a4e99aad40c/crates/bevy_render/src/color/mod.rs#L132

<img width="1280" alt="Screenshot 2024-03-02 at 23 05 09"
src="https://github.com/bevyengine/bevy/assets/8672791/451187ed-8612-456f-ad25-180d5f774188">
---
 crates/bevy_color/src/srgba.rs | 44 ++++++++++++++++++++++++++++++++++
 examples/3d/lightmaps.rs       |  3 +--
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/crates/bevy_color/src/srgba.rs b/crates/bevy_color/src/srgba.rs
index e23beea2181f3..8479af4781daa 100644
--- a/crates/bevy_color/src/srgba.rs
+++ b/crates/bevy_color/src/srgba.rs
@@ -1,3 +1,5 @@
+use std::ops::{Div, Mul};
+
 use crate::color_difference::EuclideanDistance;
 use crate::{Alpha, LinearRgba, Luminance, Mix, StandardColor, Xyza};
 use bevy_math::Vec4;
@@ -369,6 +371,48 @@ pub enum HexColorError {
     Char(char),
 }
 
+/// All color channels are scaled directly,
+/// but alpha is unchanged.
+///
+/// Values are not clamped.
+impl Mul<f32> for Srgba {
+    type Output = Self;
+
+    fn mul(self, rhs: f32) -> Self {
+        Self {
+            red: self.red * rhs,
+            green: self.green * rhs,
+            blue: self.blue * rhs,
+            alpha: self.alpha,
+        }
+    }
+}
+
+impl Mul<Srgba> for f32 {
+    type Output = Srgba;
+
+    fn mul(self, rhs: Srgba) -> Srgba {
+        rhs * self
+    }
+}
+
+/// All color channels are scaled directly,
+/// but alpha is unchanged.
+///
+/// Values are not clamped.
+impl Div<f32> for Srgba {
+    type Output = Self;
+
+    fn div(self, rhs: f32) -> Self {
+        Self {
+            red: self.red / rhs,
+            green: self.green / rhs,
+            blue: self.blue / rhs,
+            alpha: self.alpha,
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::testing::assert_approx_eq;
diff --git a/examples/3d/lightmaps.rs b/examples/3d/lightmaps.rs
index cd08712436a5d..fe7f2a8c59f2a 100644
--- a/examples/3d/lightmaps.rs
+++ b/examples/3d/lightmaps.rs
@@ -36,8 +36,7 @@ fn add_lightmaps_to_meshes(
     let exposure = 250.0;
     for (entity, name, material) in meshes.iter() {
         if &**name == "Light" {
-            materials.get_mut(material).unwrap().emissive =
-                Color::LinearRgba(LinearRgba::WHITE * exposure);
+            materials.get_mut(material).unwrap().emissive = Color::Srgba(Srgba::WHITE * exposure);
             continue;
         }