[Feature] End Structure Pool element that prevent Pool elements from spawning below y-5

src/main/java/org/betterx/bclib/api/v2/levelgen/structures/BCLStructurePoolElementTypes.java

@@ -0,0 +1,27 @@
+package org.betterx.bclib.api.v2.levelgen.structures;
+
+import org.betterx.bclib.BCLib;
+
+import com.mojang.serialization.Codec;
+import net.minecraft.core.Registry;
+import net.minecraft.core.registries.BuiltInRegistries;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.level.levelgen.structure.pools.StructurePoolElement;
+import net.minecraft.world.level.levelgen.structure.pools.StructurePoolElementType;
+
+public class BCLStructurePoolElementTypes {
+    public static final StructurePoolElementType<SingleEndPoolElement> END = register(
+            BCLib.makeID("single_end_pool_element"), SingleEndPoolElement.CODEC);
+
+
+    public static <P extends StructurePoolElement> StructurePoolElementType<P> register(
+            ResourceLocation id,
+            Codec<P> codec
+    ) {
+        return Registry.register(BuiltInRegistries.STRUCTURE_POOL_ELEMENT, id, () -> codec);
+    }
+
+    public static void ensureStaticallyLoaded() {
+        // NO-OP
+    }
+}

src/main/java/org/betterx/bclib/api/v2/levelgen/structures/SingleEndPoolElement.java

@@ -0,0 +1,89 @@
+package org.betterx.bclib.api.v2.levelgen.structures;
+
+import com.mojang.datafixers.util.Either;
+import com.mojang.serialization.Codec;
+import com.mojang.serialization.codecs.RecordCodecBuilder;
+import net.minecraft.core.BlockPos;
+import net.minecraft.core.Holder;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.util.RandomSource;
+import net.minecraft.world.level.StructureManager;
+import net.minecraft.world.level.WorldGenLevel;
+import net.minecraft.world.level.block.Rotation;
+import net.minecraft.world.level.chunk.ChunkGenerator;
+import net.minecraft.world.level.levelgen.structure.BoundingBox;
+import net.minecraft.world.level.levelgen.structure.pools.SinglePoolElement;
+import net.minecraft.world.level.levelgen.structure.pools.StructurePoolElementType;
+import net.minecraft.world.level.levelgen.structure.pools.StructureTemplatePool;
+import net.minecraft.world.level.levelgen.structure.templatesystem.StructureProcessorList;
+import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplate;
+import net.minecraft.world.level.levelgen.structure.templatesystem.StructureTemplateManager;
+
+import java.util.function.Function;
+
+public class SingleEndPoolElement extends SinglePoolElement {
+    public static final Codec<SingleEndPoolElement> CODEC = RecordCodecBuilder.create(instance -> instance.group(
+            SingleEndPoolElement.templateCodec(),
+            SingleEndPoolElement.processorsCodec(),
+            SingleEndPoolElement.projectionCodec()
+    ).apply(instance, SingleEndPoolElement::new));
+
+    public SingleEndPoolElement(
+            Either<ResourceLocation, StructureTemplate> either,
+            Holder<StructureProcessorList> holder,
+            StructureTemplatePool.Projection projection
+    ) {
+        super(either, holder, projection);
+    }
+
+    public static Function<StructureTemplatePool.Projection, SingleEndPoolElement> end(
+            ResourceLocation id,
+            Holder<StructureProcessorList> holder
+    ) {
+        return projection -> new SingleEndPoolElement(
+                Either.left(id),
+                holder,
+                projection
+        );
+    }
+
+    @Override
+    public boolean place(
+            StructureTemplateManager structureTemplateManager,
+            WorldGenLevel worldGenLevel,
+            StructureManager structureManager,
+            ChunkGenerator chunkGenerator,
+            BlockPos blockPos,
+            BlockPos blockPos2,
+            Rotation rotation,
+            BoundingBox boundingBox,
+            RandomSource randomSource,
+            boolean bl
+    ) {
+        //in the end, we don't want to generate anything below y=5
+        if (blockPos.getY() < 5) return false;
+
+        return super.place(
+                structureTemplateManager,
+                worldGenLevel,
+                structureManager,
+                chunkGenerator,
+                blockPos,
+                blockPos2,
+                rotation,
+                boundingBox,
+                randomSource,
+                bl
+        );
+    }
+
+    @Override
+    public StructurePoolElementType<?> getType() {
+        return BCLStructurePoolElementTypes.END;
+    }
+
+    @Override
+    public String toString() {
+        return "SingleEnd[" + this.template + "]";
+    }
+}