PaperMC/patches/api/0496-Optimise-color-distance-check-in-MapPalette-by-remov.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Barnaby <22575741+barnabwhy@users.noreply.github.com>
Date: Sat, 29 Jun 2024 12:04:48 +0100
Subject: [PATCH] Optimise color distance check in MapPalette by removing
 floating point math


diff --git a/src/main/java/org/bukkit/map/MapPalette.java b/src/main/java/org/bukkit/map/MapPalette.java
index c80faa079eca1564847070f0338fc98024639829..55a46db9d73885ea967ac929013906b687e476bb 100644
--- a/src/main/java/org/bukkit/map/MapPalette.java
+++ b/src/main/java/org/bukkit/map/MapPalette.java
@@ -29,14 +29,19 @@ public final class MapPalette {
     }
 
     private static double getDistance(@NotNull Color c1, @NotNull Color c2) {
-        double rmean = (c1.getRed() + c2.getRed()) / 2.0;
-        double r = c1.getRed() - c2.getRed();
-        double g = c1.getGreen() - c2.getGreen();
+        // Paper start - Optimize color distance calculation by removing floating point math
+        int rsum = c1.getRed() + c2.getRed(); // Use sum instead of mean for no division
+        int r = c1.getRed() - c2.getRed();
+        int g = c1.getGreen() - c2.getGreen();
         int b = c1.getBlue() - c2.getBlue();
-        double weightR = 2 + rmean / 256.0;
-        double weightG = 4.0;
-        double weightB = 2 + (255 - rmean) / 256.0;
+        // All weights are 512x their original to avoid floating point division
+        int weightR = 1024 + rsum;
+        int weightG = 2048;
+        int weightB = 1024 + (255*2 - rsum);
+
+        // Division by 256 here is unnecessary as this won't change the result of the sort
         return weightR * r * r + weightG * g * g + weightB * b * b;
+        // Paper end
     }
 
     @NotNull