Implement linear patterns using RandomPattern + SimpleRandom (#2630)

worldedit-core/src/main/java/com/fastasyncworldedit/core/extension/factory/parser/pattern/Linear2DPatternParser.java

@@ -2,7 +2,7 @@ package com.fastasyncworldedit.core.extension.factory.parser.pattern;
 
 import com.fastasyncworldedit.core.configuration.Caption;
 import com.fastasyncworldedit.core.extension.factory.parser.RichParser;
-import com.fastasyncworldedit.core.function.pattern.Linear2DBlockPattern;
+import com.fastasyncworldedit.core.math.random.Linear2DRandom;
 import com.google.common.base.Preconditions;
 import com.sk89q.worldedit.WorldEdit;
 import com.sk89q.worldedit.command.util.SuggestionHelper;
@@ -14,7 +14,6 @@ import com.sk89q.worldedit.util.formatting.text.TextComponent;
 import com.sk89q.worldedit.world.block.BlockStateHolder;
 
 import javax.annotation.Nonnull;
-import java.util.Set;
 import java.util.stream.Stream;
 
 public class Linear2DPatternParser extends RichParser<Pattern> {
@@ -59,9 +58,8 @@ public class Linear2DPatternParser extends RichParser<Pattern> {
             zScale = Integer.parseInt(arguments[2]);
             Preconditions.checkArgument(zScale != 0);
         }
-        if (inner instanceof RandomPattern) {
+        if (inner instanceof RandomPattern rp) {
-            Set<Pattern> patterns = ((RandomPattern) inner).getPatterns();
+            return new RandomPattern(new Linear2DRandom(xScale, zScale), rp);
-            return new Linear2DBlockPattern(patterns.toArray(new Pattern[0]), xScale, zScale);
         }
         throw new InputParseException(TextComponent.of("Pattern " + inner.getClass().getSimpleName()
                 + " cannot be used with " + getPrefix()));

worldedit-core/src/main/java/com/fastasyncworldedit/core/extension/factory/parser/pattern/Linear3DPatternParser.java

@@ -2,7 +2,7 @@ package com.fastasyncworldedit.core.extension.factory.parser.pattern;
 
 import com.fastasyncworldedit.core.configuration.Caption;
 import com.fastasyncworldedit.core.extension.factory.parser.RichParser;
-import com.fastasyncworldedit.core.function.pattern.Linear3DBlockPattern;
+import com.fastasyncworldedit.core.math.random.Linear3DRandom;
 import com.google.common.base.Preconditions;
 import com.sk89q.worldedit.WorldEdit;
 import com.sk89q.worldedit.command.util.SuggestionHelper;
@@ -14,7 +14,6 @@ import com.sk89q.worldedit.util.formatting.text.TextComponent;
 import com.sk89q.worldedit.world.block.BlockStateHolder;
 
 import javax.annotation.Nonnull;
-import java.util.Set;
 import java.util.stream.Stream;
 
 public class Linear3DPatternParser extends RichParser<Pattern> {
@@ -64,9 +63,8 @@ public class Linear3DPatternParser extends RichParser<Pattern> {
             zScale = Integer.parseInt(arguments[3]);
             Preconditions.checkArgument(zScale != 0);
         }
-        if (inner instanceof RandomPattern) {
+        if (inner instanceof RandomPattern rp) {
-            Set<Pattern> patterns = ((RandomPattern) inner).getPatterns();
+            return new RandomPattern(new Linear3DRandom(xScale, yScale, zScale), rp);
-            return new Linear3DBlockPattern(patterns.toArray(new Pattern[0]), xScale, yScale, zScale);
         }
         throw new InputParseException(TextComponent.of("Pattern " + inner.getClass().getSimpleName()
                 + " cannot be used with " + getPrefix()));

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/Linear2DBlockPattern.java

@@ -9,6 +9,11 @@ import com.sk89q.worldedit.world.block.BaseBlock;
 
 import static java.lang.Math.floorDiv;
 
+/**
+ * @deprecated replaced by {@link com.sk89q.worldedit.function.pattern.RandomPattern}
+ * combined with {@link com.fastasyncworldedit.core.math.random.Linear2DRandom}.
+ */
+@Deprecated(forRemoval = true, since = "TODO")
 public class Linear2DBlockPattern extends AbstractPattern {
 
     private final Pattern[] patternsArray;

worldedit-core/src/main/java/com/fastasyncworldedit/core/function/pattern/Linear3DBlockPattern.java

@@ -9,6 +9,11 @@ import com.sk89q.worldedit.world.block.BaseBlock;
 
 import static java.lang.Math.floorDiv;
 
+/**
+ * @deprecated replaced by {@link com.sk89q.worldedit.function.pattern.RandomPattern}
+ * combined with {@link com.fastasyncworldedit.core.math.random.Linear3DRandom}.
+ */
+@Deprecated(forRemoval = true, since = "TODO")
 public class Linear3DBlockPattern extends AbstractPattern {
 
     private final Pattern[] patternsArray;

worldedit-core/src/main/java/com/fastasyncworldedit/core/math/random/Linear2DRandom.java

@@ -0,0 +1,50 @@
+package com.fastasyncworldedit.core.math.random;
+
+import static com.fastasyncworldedit.core.math.random.Linear3DRandom.doubleDiv;
+import static java.lang.Math.floorDiv;
+
+/**
+ * A {@link SimpleRandom} that deterministically maps coordinates
+ * to values.
+ * @since TODO
+ */
+public class Linear2DRandom implements SimpleRandom {
+    private final int xScale;
+    private final int zScale;
+
+    /**
+     * Creates a new {@link Linear2DRandom} instance
+     *
+     * @param xScale the scale applied to the x component of a coordinate
+     * @param zScale the scale applied to the z component of a coordinate
+     */
+    public Linear2DRandom(final int xScale, final int zScale) {
+        this.xScale = xScale;
+        this.zScale = zScale;
+    }
+
+    @Override
+    public double nextDouble(final int x, final int y, final int z) {
+        return nextDouble(x, y, z, 1d);
+    }
+
+    @Override
+    public double nextDouble(final int x, final int y, final int z, double bound) {
+        double index = (doubleDiv(x, this.xScale) + doubleDiv(z, this.zScale)) % bound;
+        if (index < 0) {
+            index += bound;
+        }
+        return index;
+
+    }
+
+    @Override
+    public int nextInt(final int x, final int y, final int z, final int bound) {
+        int index = (floorDiv(x, this.xScale) + floorDiv(z, this.zScale)) % bound;
+        if (index < 0) {
+            index += bound;
+        }
+        return index;
+    }
+
+}

worldedit-core/src/main/java/com/fastasyncworldedit/core/math/random/Linear3DRandom.java

@@ -0,0 +1,58 @@
+package com.fastasyncworldedit.core.math.random;
+
+import static java.lang.Math.floorDiv;
+
+/**
+ * A {@link SimpleRandom} that deterministically maps coordinates
+ * to values.
+ * @since TODO
+ */
+public class Linear3DRandom implements SimpleRandom {
+
+    private final int xScale;
+    private final int yScale;
+    private final int zScale;
+
+    /**
+     * Creates a new {@link Linear3DRandom} instance
+     *
+     * @param xScale the scale applied to the x component of a coordinate
+     * @param yScale the scale applied to the y component of a coordinate
+     * @param zScale the scale applied to the z component of a coordinate
+     */
+    public Linear3DRandom(final int xScale, final int yScale, final int zScale) {
+        this.xScale = xScale;
+        this.yScale = yScale;
+        this.zScale = zScale;
+    }
+
+    @Override
+    public double nextDouble(final int x, final int y, final int z) {
+        return nextDouble(x, y, z, 1d);
+    }
+
+    @Override
+    public double nextDouble(final int x, final int y, final int z, double bound) {
+        double index = (doubleDiv(x, this.xScale) + doubleDiv(y, this.yScale) + doubleDiv(z, this.zScale)) % bound;
+        if (index < 0) {
+            index += bound;
+        }
+        return index;
+    }
+
+    // used to avoid explicit conversion at call site
+    static double doubleDiv(double dividend, double divisor) {
+        // add a minimal value to avoid too many integral values hitting the exact weight of an entry in SimpleRandomCollection
+        return Math.nextUp(dividend) / divisor;
+    }
+
+    @Override
+    public int nextInt(final int x, final int y, final int z, final int bound) {
+        int index = (floorDiv(x, this.xScale) + floorDiv(y, this.yScale) + floorDiv(z, this.zScale)) % bound;
+        if (index < 0) {
+            index += bound;
+        }
+        return index;
+    }
+
+}

worldedit-core/src/main/java/com/fastasyncworldedit/core/math/random/SimpleRandom.java

@@ -13,6 +13,20 @@ public interface SimpleRandom {
      */
     double nextDouble(int x, int y, int z);
 
+    /**
+     * Generate a random double from three integer components.
+     * The generated value is between 0 (inclusive) and {@code bound} (exclusive).
+     *
+     * @param x     the first component
+     * @param y     the second component
+     * @param z     the third component
+     * @param bound upper bound (exclusive)
+     * @return a double between 0 (inclusive) and {@code bound} (exclusive)
+     */
+    default double nextDouble(int x, int y, int z, double bound) {
+        return nextDouble(x, y, z) * bound;
+    }
+
     /**
      * Generate a random integer from three integer components.
      * The generated value is between 0 (inclusive) and 1 (exclusive)
@@ -24,8 +38,8 @@ public interface SimpleRandom {
      * @return a random integer between 0 (inclusive) and {@code bound} (exclusive)
      */
     default int nextInt(int x, int y, int z, int bound) {
-        double val = nextDouble(x, y, z);
+        double val = nextDouble(x, y, z, bound);
-        return (int) (val * bound);
+        return (int) val;
     }
 
 }

worldedit-core/src/main/java/com/fastasyncworldedit/core/util/collection/SimpleRandomCollection.java

@@ -36,7 +36,7 @@ public class SimpleRandomCollection<E> extends RandomCollection<E> {
 
     @Override
     public E next(int x, int y, int z) {
-        return map.ceilingEntry(getRandom().nextDouble(x, y, z) * this.total).getValue();
+        return map.ceilingEntry(getRandom().nextDouble(x, y, z, this.total)).getValue();
     }
 
 }