redesign for Structures

core/src/test/java/art/arcane/iris/core/lifecycle/WorldLifecycleStagingTest.java

@@ -30,6 +30,17 @@ public class WorldLifecycleStagingTest {
         assertSame(generator, WorldLifecycleStaging.consumeStemGenerator("world"));
     }
 
+    @Test
+    public void stagedStemGeneratorIsConsumedWhenLevelIdDiffersFromWorldName() {
+        ChunkGenerator generator = mock(ChunkGenerator.class);
+
+        WorldLifecycleStaging.stageStemGenerator("iris_world", generator);
+
+        assertSame(generator, WorldLifecycleStaging.consumeStemGenerator("world"));
+        assertNull(WorldLifecycleStaging.consumeStemGenerator("iris_world"));
+        assertNull(WorldLifecycleStaging.consumeStemGenerator("world"));
+    }
+
     @Test
     public void clearAllRemovesGeneratorBiomeAndStemState() {
         ChunkGenerator generator = mock(ChunkGenerator.class);

core/src/test/java/art/arcane/iris/engine/framework/StructurePlacementGridTest.java

@@ -0,0 +1,104 @@
+/*
+ * Iris is a World Generator for Minecraft Bukkit Servers
+ * Copyright (c) 2022 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 art.arcane.iris.engine.framework;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
+import static org.junit.Assert.assertTrue;
+
+public class StructurePlacementGridTest {
+    @Test
+    public void randomSpreadStartIsDeterministic() {
+        boolean first = StructurePlacementGrid.randomSpreadStart(5, 7, 32, 8, 165745296, 12345L);
+        boolean second = StructurePlacementGrid.randomSpreadStart(5, 7, 32, 8, 165745296, 12345L);
+        assertEquals(first, second);
+    }
+
+    @Test
+    public void randomSpreadStartYieldsExactlyOneStartPerGridCell() {
+        int spacing = 32;
+        int separation = 8;
+        int salt = 165745296;
+        long seed = 99L;
+        int count = 0;
+        for (int cx = 0; cx < spacing; cx++) {
+            for (int cz = 0; cz < spacing; cz++) {
+                if (StructurePlacementGrid.randomSpreadStart(cx, cz, spacing, separation, salt, seed)) {
+                    count++;
+                }
+            }
+        }
+        assertEquals(1, count);
+    }
+
+    @Test
+    public void randomSpreadStartVariesAcrossCells() {
+        int spacing = 32;
+        int separation = 8;
+        int salt = 165745296;
+        long seed = 99L;
+        int starts = 0;
+        for (int cellX = 0; cellX < 4; cellX++) {
+            for (int cellZ = 0; cellZ < 4; cellZ++) {
+                for (int x = 0; x < spacing; x++) {
+                    for (int z = 0; z < spacing; z++) {
+                        int cx = cellX * spacing + x;
+                        int cz = cellZ * spacing + z;
+                        if (StructurePlacementGrid.randomSpreadStart(cx, cz, spacing, separation, salt, seed)) {
+                            starts++;
+                        }
+                    }
+                }
+            }
+        }
+        assertEquals(16, starts);
+    }
+
+    @Test
+    public void mixIsDeterministicAndSensitiveToInputs() {
+        assertEquals(StructurePlacementGrid.mix(1L, 2, 3, 4), StructurePlacementGrid.mix(1L, 2, 3, 4));
+        assertNotEquals(StructurePlacementGrid.mix(1L, 2, 3, 4), StructurePlacementGrid.mix(1L, 2, 3, 5));
+        assertNotEquals(StructurePlacementGrid.mix(1L, 2, 3, 4), StructurePlacementGrid.mix(2L, 2, 3, 4));
+    }
+
+    @Test
+    public void differentSaltsShiftStartPositions() {
+        int spacing = 32;
+        int separation = 8;
+        long seed = 7L;
+        int matches = 0;
+        int total = 0;
+        for (int cx = 0; cx < spacing; cx++) {
+            for (int cz = 0; cz < spacing; cz++) {
+                boolean a = StructurePlacementGrid.randomSpreadStart(cx, cz, spacing, separation, 10387312, seed);
+                boolean b = StructurePlacementGrid.randomSpreadStart(cx, cz, spacing, separation, 165745296, seed);
+                if (a) {
+                    total++;
+                }
+                if (a && b) {
+                    matches++;
+                }
+            }
+        }
+        assertEquals(1, total);
+        assertTrue(matches <= total);
+    }
+}