From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: nostalgic853 <yuu8583@proton.me>
Date: Tue, 25 Oct 2022 00:28:35 +0800
Subject: [PATCH] Carpet-Fixes: Optimized getBiome method

Original license: MIT
Original project: https://github.com/fxmorin/carpet-fixes

Optimized the getBiome call to be 25% - 75% faster
This is a fully vanilla optimization.

diff --git a/net/minecraft/world/level/biome/BiomeManager.java b/net/minecraft/world/level/biome/BiomeManager.java
index 73962e79a0f3d892e3155443a1b84508b0f4042e..a48175a7ebb1788ace46395621ed78d910178a53 100644
--- a/net/minecraft/world/level/biome/BiomeManager.java
+++ b/net/minecraft/world/level/biome/BiomeManager.java
@@ -14,6 +14,7 @@ public class BiomeManager {
     private static final int ZOOM_MASK = 3;
     private final BiomeManager.NoiseBiomeSource noiseBiomeSource;
     private final long biomeZoomSeed;
+    private static final double maxOffset = 0.4500000001D; // Leaf - Carpet-Fixes - Optimized getBiome method
 
     public BiomeManager(BiomeManager.NoiseBiomeSource noiseBiomeSource, long biomeZoomSeed) {
         this.noiseBiomeSource = noiseBiomeSource;
@@ -29,39 +30,67 @@ public class BiomeManager {
     }
 
     public Holder<Biome> getBiome(BlockPos pos) {
-        int i = pos.getX() - 2;
-        int i1 = pos.getY() - 2;
-        int i2 = pos.getZ() - 2;
-        int i3 = i >> 2;
-        int i4 = i1 >> 2;
-        int i5 = i2 >> 2;
-        double d = (i & 3) / 4.0;
-        double d1 = (i1 & 3) / 4.0;
-        double d2 = (i2 & 3) / 4.0;
-        int i6 = 0;
-        double d3 = Double.POSITIVE_INFINITY;
+        // Leaf start - Carpet-Fixes - Optimized getBiome method
+        int xMinus2 = pos.getX() - 2;
+        int yMinus2 = pos.getY() - 2;
+        int zMinus2 = pos.getZ() - 2;
+        int x = xMinus2 >> 2; // BlockPos to BiomePos
+        int y = yMinus2 >> 2;
+        int z = zMinus2 >> 2;
+        double quartX = (double) (xMinus2 & 3) / 4.0; // quartLocal divided by 4
+        double quartY = (double) (yMinus2 & 3) / 4.0; // 0/4, 1/4, 2/4, 3/4
+        double quartZ = (double) (zMinus2 & 3) / 4.0; // [0, 0.25, 0.5, 0.75]
+        int smallestX = 0;
+        double smallestDist = Double.POSITIVE_INFINITY;
+        for (int biomeX = 0; biomeX < 8; ++biomeX) {
+            boolean everyOtherQuad = (biomeX & 4) == 0; // 1 1 1 1 0 0 0 0
+            boolean everyOtherPair = (biomeX & 2) == 0; // 1 1 0 0 1 1 0 0
+            boolean everyOther = (biomeX & 1) == 0; // 1 0 1 0 1 0 1 0
+            double quartXX = everyOtherQuad ? quartX : quartX - 1.0; //[-1.0,-0.75,-0.5,-0.25,0.0,0.25,0.5,0.75]
+            double quartYY = everyOtherPair ? quartY : quartY - 1.0;
+            double quartZZ = everyOther ? quartZ : quartZ - 1.0;
 
-        for (int i7 = 0; i7 < 8; i7++) {
-            boolean flag = (i7 & 4) == 0;
-            boolean flag1 = (i7 & 2) == 0;
-            boolean flag2 = (i7 & 1) == 0;
-            int i8 = flag ? i3 : i3 + 1;
-            int i9 = flag1 ? i4 : i4 + 1;
-            int i10 = flag2 ? i5 : i5 + 1;
-            double d4 = flag ? d : d - 1.0;
-            double d5 = flag1 ? d1 : d1 - 1.0;
-            double d6 = flag2 ? d2 : d2 - 1.0;
-            double fiddledDistance = getFiddledDistance(this.biomeZoomSeed, i8, i9, i10, d4, d5, d6);
-            if (d3 > fiddledDistance) {
-                i6 = i7;
-                d3 = fiddledDistance;
+            //This code block is new
+            double maxQuartYY = 0.0, maxQuartZZ = 0.0;
+            if (biomeX != 0) {
+                maxQuartYY = Mth.square(Math.max(quartYY + maxOffset, Math.abs(quartYY - maxOffset)));
+                maxQuartZZ = Mth.square(Math.max(quartZZ + maxOffset, Math.abs(quartZZ - maxOffset)));
+                double maxQuartXX = Mth.square(Math.max(quartXX + maxOffset, Math.abs(quartXX - maxOffset)));
+                if (smallestDist < maxQuartXX + maxQuartYY + maxQuartZZ) continue;
             }
-        }
+            int xx = everyOtherQuad ? x : x + 1;
+            int yy = everyOtherPair ? y : y + 1;
+            int zz = everyOther ? z : z + 1;
+
+            //I transferred the code from method_38106 to here, so I could call continue halfway through
+            long seed = LinearCongruentialGenerator.next(this.biomeZoomSeed, xx);
+            seed = LinearCongruentialGenerator.next(seed, yy);
+            seed = LinearCongruentialGenerator.next(seed, zz);
+            seed = LinearCongruentialGenerator.next(seed, xx);
+            seed = LinearCongruentialGenerator.next(seed, yy);
+            seed = LinearCongruentialGenerator.next(seed, zz);
+            double offsetX = getFiddle(seed);
+            double sqrX = Mth.square(quartXX + offsetX);
+            if (biomeX != 0 && smallestDist < sqrX + maxQuartYY + maxQuartZZ) continue; //skip the rest of the loop
+            seed = LinearCongruentialGenerator.next(seed, this.biomeZoomSeed);
+            double offsetY = getFiddle(seed);
+            double sqrY = Mth.square(quartYY + offsetY);
+            if (biomeX != 0 && smallestDist < sqrX + sqrY + maxQuartZZ) continue; // skip the rest of the loop
+            seed = LinearCongruentialGenerator.next(seed, this.biomeZoomSeed);
+            double offsetZ = getFiddle(seed);
+            double biomeDist = sqrX + sqrY + Mth.square(quartZZ + offsetZ);
 
-        int i7x = (i6 & 4) == 0 ? i3 : i3 + 1;
-        int i11 = (i6 & 2) == 0 ? i4 : i4 + 1;
-        int i12 = (i6 & 1) == 0 ? i5 : i5 + 1;
-        return this.noiseBiomeSource.getNoiseBiome(i7x, i11, i12);
+            if (smallestDist > biomeDist) {
+                smallestX = biomeX;
+                smallestDist = biomeDist;
+            }
+        }
+        return this.noiseBiomeSource.getNoiseBiome(
+            (smallestX & 4) == 0 ? x : x + 1,
+            (smallestX & 2) == 0 ? y : y + 1,
+            (smallestX & 1) == 0 ? z : z + 1
+        );
+        // Leaf end - Carpet-Fixes - Optimized getBiome method
     }
 
     public Holder<Biome> getNoiseBiomeAtPosition(double x, double y, double z) {