Spiral util for infininity

src/main/java/com/volmit/iris/util/math/Spiral.java

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+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2021 Arcane Arts (Volmit Software)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.volmit.iris.util.math;
+
+import lombok.AllArgsConstructor;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Iterator;
+
+/**
+ * Represents a spiraler which can start from any point within Long.MAX_VALUE by Long.MAX_VALUE and iterate anywhere.
+ */
+public record Spiral(Position2 start, long max) implements Iterable<Position2> {
+    @SuppressWarnings("ConstantConditions")
+    public static Position2 next(Position2 p) {
+        int x = p.getX();
+        int z = p.getZ();
+        int ax = Math.abs(x);
+        int az = Math.abs(z);
+
+        if (x == 0 && z == 0) {
+            return p.add(1, 0);
+        }
+
+        if (ax == az) {
+            if (x > 0 && z > 0) return left(p);
+            else if (x < 0 && z > 0) return down(p);
+            else if (x < 0 && z < 0) return right(p);
+            else if (x > 0 && z < 0) return up(p);
+        } else {
+            if (x > z && ax > az) return up(p);
+            else if (x < z && ax < az) return left(p);
+            else if (x < z && ax > az) return down(p);
+            else if (x > z && ax < az) return right(p);
+        }
+
+        return p;
+    }
+
+    public static Spiral from(Position2 p, long iterations)
+    {
+        return new Spiral(p, iterations);
+    }
+
+    private static Position2 down(Position2 p) {
+        return p.add(0, -1);
+    }
+
+    private static Position2 up(Position2 p) {
+        return p.add(0, 1);
+    }
+
+    private static Position2 left(Position2 p) {
+        return p.add(-1, 0);
+    }
+
+    private static Position2 right(Position2 p) {
+        return p.add(1, 0);
+    }
+
+    @NotNull
+    @Override
+    public Iterator<Position2> iterator() {
+        return new SpiralIterator(0, this, start);
+    }
+
+    @AllArgsConstructor
+    static class SpiralIterator implements Iterator<Position2> {
+        private long itr = 0;
+        private final Spiral s;
+        private Position2 cursor;
+
+        @Override
+        public boolean hasNext() {
+            return itr < s.max();
+        }
+
+        @Override
+        public Position2 next() {
+            Position2 m = cursor;
+            cursor = Spiral.next(cursor);
+            itr++;
+            return m;
+        }
+    }
+}