From 1f8d9a710f854a25bd8590ba70410b775efb95e4 Mon Sep 17 00:00:00 2001
From: dfsek <dfsek@protonmail.com>
Date: Sat, 21 Nov 2020 16:14:09 -0700
Subject: [PATCH] Implement NoiseFunction2 cache

---
 .../com/dfsek/terra/math/NoiseFunction2.java  | 27 ++++++++++++++++-
 src/test/java/NoiseTest.java                  | 29 +++++++++++++++----
 2 files changed, 50 insertions(+), 6 deletions(-)

diff --git a/src/main/java/com/dfsek/terra/math/NoiseFunction2.java b/src/main/java/com/dfsek/terra/math/NoiseFunction2.java
index 898b760c2..ac3ab8d87 100644
--- a/src/main/java/com/dfsek/terra/math/NoiseFunction2.java
+++ b/src/main/java/com/dfsek/terra/math/NoiseFunction2.java
@@ -4,10 +4,12 @@ import com.dfsek.terra.generation.config.NoiseBuilder;
 import org.polydev.gaea.math.FastNoiseLite;
 import parsii.eval.Expression;
 
+import java.util.HashMap;
 import java.util.List;
 
 public class NoiseFunction2 implements NoiseFunction {
     private final FastNoiseLite gen;
+    private final Cache cache = new Cache();
 
     public NoiseFunction2(long seed, NoiseBuilder builder) {
         this.gen = builder.build((int) seed);
@@ -20,11 +22,34 @@ public class NoiseFunction2 implements NoiseFunction {
 
     @Override
     public double eval(List<Expression> list) {
-        return gen.getNoise(list.get(0).evaluate(), list.get(1).evaluate());
+        return cache.get(gen, (int) list.get(0).evaluate(), (int) list.get(1).evaluate());
+    }
+
+    /**
+     * Evaluate without cache. For testing.
+     *
+     * @param list Parameters.
+     * @return Result.
+     */
+    public double evalNoCache(List<Expression> list) {
+        return gen.getNoise((int) list.get(0).evaluate(), (int) list.get(1).evaluate());
     }
 
     @Override
     public boolean isNaturalFunction() {
         return true;
     }
+
+    private static class Cache {
+        private final HashMap<Long, Double> map = new HashMap<>();
+
+        public double get(FastNoiseLite noise, int x, int z) {
+            long key = (((long) x) << 32) + z;
+
+            return map.computeIfAbsent(key, k -> {
+                if(map.size() > 512) map.clear();
+                return noise.getNoise(x, z);
+            });
+        }
+    }
 }
diff --git a/src/test/java/NoiseTest.java b/src/test/java/NoiseTest.java
index b11cacc94..7be68ad2d 100644
--- a/src/test/java/NoiseTest.java
+++ b/src/test/java/NoiseTest.java
@@ -9,13 +9,32 @@ public class NoiseTest {
     @Test
     public void noise() {
         NoiseFunction2 noiseFunction = new NoiseFunction2(12345, new NoiseBuilder());
-
+        System.out.println("Cache:");
         for(int i = 0; i < 10; i++) {
             long l = System.nanoTime();
-            for(int j = 0; j < 1000000; j++) {
-                noiseFunction.eval(Arrays.asList(get(j), get(i)));
-                noiseFunction.eval(Arrays.asList(get(j), get(i)));
-                noiseFunction.eval(Arrays.asList(get(j), get(i)));
+            for(int j = 0; j < 20000; j++) {
+                for(int x = 0; x < 4; x++) {
+                    for(int y = 0; y < 64; y++) {
+                        for(int z = 0; z < 4; z++) {
+                            noiseFunction.eval(Arrays.asList(get(j * 16 + (x * 4)), get(i * 16 + (z * 4))));
+                        }
+                    }
+                }
+            }
+            double n = System.nanoTime() - l;
+            System.out.println(n / 1000000 + "ms");
+        }
+        System.out.println("No Cache:");
+        for(int i = 0; i < 10; i++) {
+            long l = System.nanoTime();
+            for(int j = 0; j < 20000; j++) {
+                for(int x = 0; x < 4; x++) {
+                    for(int y = 0; y < 64; y++) {
+                        for(int z = 0; z < 4; z++) {
+                            noiseFunction.evalNoCache(Arrays.asList(get(j * 16 + (x * 4)), get(i * 16 + (z * 4))));
+                        }
+                    }
+                }
             }
             double n = System.nanoTime() - l;
             System.out.println(n / 1000000 + "ms");