From a97fda7ef0c777ca96e7e2235680ae65f88fca6b Mon Sep 17 00:00:00 2001
From: themode <themode@outlook.fr>
Date: Fri, 24 Dec 2021 10:45:03 +0100
Subject: [PATCH] Force palette dimension to be a power of 2. Improve
 performance

---
 .../server/instance/palette/PaletteImpl.java  |  4 +-
 src/test/java/instance/PaletteTest.java       | 37 ++++++++++++-------
 2 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/src/main/java/net/minestom/server/instance/palette/PaletteImpl.java b/src/main/java/net/minestom/server/instance/palette/PaletteImpl.java
index 837b13559..47495e87e 100644
--- a/src/main/java/net/minestom/server/instance/palette/PaletteImpl.java
+++ b/src/main/java/net/minestom/server/instance/palette/PaletteImpl.java
@@ -36,6 +36,9 @@ final class PaletteImpl implements Palette, Cloneable {
     private Int2IntOpenHashMap valueToPaletteMap;
 
     PaletteImpl(int dimension, int maxBitsPerEntry, int bitsPerEntry, int bitsIncrement) {
+        if (dimension < 1 || dimension % 2 != 0)
+            throw new IllegalArgumentException("Dimension must be positive and power of 2");
+
         this.dimension = dimension;
         this.size = dimension * dimension * dimension;
         this.maxBitsPerEntry = maxBitsPerEntry;
@@ -218,7 +221,6 @@ final class PaletteImpl implements Palette, Cloneable {
     }
 
     int getSectionIndex(int x, int y, int z) {
-        y = Math.floorMod(y, dimension);
         return y << (dimension / 2) | z << (dimension / 4) | x;
     }
 
diff --git a/src/test/java/instance/PaletteTest.java b/src/test/java/instance/PaletteTest.java
index 3cbe4626d..4bcbc875a 100644
--- a/src/test/java/instance/PaletteTest.java
+++ b/src/test/java/instance/PaletteTest.java
@@ -1,27 +1,18 @@
 package instance;
 
 import net.minestom.server.instance.palette.Palette;
-import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import java.util.ArrayList;
 import java.util.List;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.*;
 
 public class PaletteTest {
-    private List<Palette> palettes = new ArrayList<>();
-
-    @BeforeEach
-    public void reset() {
-        for (int i = 4; i < 16; i++) {
-            palettes.add(Palette.newPalette(i, 5, 3, 1));
-        }
-    }
 
     @Test
-    public void testPlacement() {
+    public void placement() {
+        var palettes = testPalettes();
         for (Palette palette : palettes) {
             final int dimension = palette.dimension();
             assertEquals(0, palette.get(0, 0, 0), "Default value should be 0");
@@ -55,7 +46,8 @@ public class PaletteTest {
     }
 
     @Test
-    public void testPlacementNeg() {
+    public void negPlacement() {
+        var palettes = testPalettes();
         for (Palette palette : palettes) {
             assertThrows(IllegalArgumentException.class, () -> palette.set(-1, 0, 0, 64));
             assertThrows(IllegalArgumentException.class, () -> palette.set(0, -1, 0, 64));
@@ -68,7 +60,7 @@ public class PaletteTest {
     }
 
     @Test
-    public void testResize() {
+    public void resize() {
         Palette palette = Palette.newPalette(16, 5, 2, 1);
         palette.set(0, 0, 0, 1);
         assertEquals(2, palette.bitsPerEntry());
@@ -84,4 +76,21 @@ public class PaletteTest {
         assertEquals(3, palette.get(0, 0, 2));
         assertEquals(4, palette.get(0, 0, 3));
     }
+
+    @Test
+    public void dimension() {
+        assertThrows(Exception.class, () -> Palette.newPalette(0, 5, 3, 1));
+        assertThrows(Exception.class, () -> Palette.newPalette(1, 5, 3, 1));
+        assertDoesNotThrow(() -> Palette.newPalette(2, 5, 3, 1));
+        assertThrows(Exception.class, () -> Palette.newPalette(3, 5, 3, 1));
+        assertDoesNotThrow(() -> Palette.newPalette(4, 5, 3, 1));
+    }
+
+    private static List<Palette> testPalettes() {
+        List<Palette> palettes = new ArrayList<>();
+        for (int i = 4; i < 16; i += 2) {
+            palettes.add(Palette.newPalette(i, 5, 3, 1));
+        }
+        return palettes;
+    }
 }