Prevent players from exiting the spawn using barriers

src/main/java/io/github/haykam821/minefield/game/map/MinefieldMap.java

@@ -1,27 +1,73 @@
 package io.github.haykam821.minefield.game.map;
 
+import net.minecraft.block.BlockState;
+import net.minecraft.block.Blocks;
 import net.minecraft.server.MinecraftServer;
 import net.minecraft.server.network.ServerPlayerEntity;
 import net.minecraft.server.world.ServerWorld;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.math.Box;
 import net.minecraft.util.math.Vec3d;
 import net.minecraft.world.gen.chunk.ChunkGenerator;
 import xyz.nucleoid.map_templates.BlockBounds;
 import xyz.nucleoid.map_templates.MapTemplate;
 import xyz.nucleoid.plasmid.game.world.generator.TemplateChunkGenerator;
 
 public class MinefieldMap {
+	private static final BlockState AIR = Blocks.AIR.getDefaultState();
+
 	private final MapTemplate template;
+	private final BlockBounds start;
+	private final Box spawnBox;
 	private final Vec3d spawnPos;
 	private final BlockBounds end;
 	private final Vec3d guideTextPos;
 
 	public MinefieldMap(MapTemplate template, BlockBounds start, BlockBounds end, Vec3d guideTextPos) {
 		this.template = template;
+		this.start = start;
+		this.spawnBox = new Box(start.min().add(0, 1, 0), start.max().add(1, 3, 1));
 		this.spawnPos = start.centerBottom().add(0, 1, 0);
 		this.end = end;
 		this.guideTextPos = guideTextPos;
 	}
 
+	public void removeBarrierPerimeter(ServerWorld world) {
+		BlockPos.Mutable pos = new BlockPos.Mutable();
+
+		pos.setY(this.start.min().getY() + 2);
+
+		int barrierMinX = this.start.min().getX() - 1;
+		int barrierMaxX = this.start.max().getX() + 1;
+
+		int barrierMinZ = this.start.min().getZ() - 1;
+		int barrierMaxZ = this.start.max().getZ() + 1;
+
+		for (int x = barrierMinX; x <= barrierMaxX; x += 1) {
+			pos.setX(x);
+
+			pos.setZ(barrierMinZ);
+			world.setBlockState(pos, AIR);
+
+			pos.setZ(barrierMaxZ);
+			world.setBlockState(pos, AIR);
+		}
+
+		for (int z = barrierMinZ + 1; z <= barrierMaxZ - 1; z += 1) {
+			pos.setZ(z);
+
+			pos.setX(barrierMinX);
+			world.setBlockState(pos, AIR);
+
+			pos.setX(barrierMaxX);
+			world.setBlockState(pos, AIR);
+		}
+	}
+
+	public boolean isInSpawn(ServerPlayerEntity player) {
+		return this.spawnBox.contains(player.getPos());
+	}
+
 	public Vec3d getSpawnPos() {
 		return this.spawnPos;
 	}

src/main/java/io/github/haykam821/minefield/game/map/MinefieldMapBuilder.java

@@ -15,13 +15,46 @@ public class MinefieldMapBuilder {
 	private static final BlockState MINES_FLOOR = Blocks.SANDSTONE.getDefaultState();
 	private static final BlockState MINE = Blocks.STONE_PRESSURE_PLATE.getDefaultState();
 	private static final BlockState END_FLOOR = Blocks.EMERALD_BLOCK.getDefaultState();
+	private static final BlockState BARRIER = Blocks.BARRIER.getDefaultState();
 
 	private final MinefieldConfig config;
 
 	public MinefieldMapBuilder(MinefieldConfig config) {
 		this.config = config;
 	}
 
+	private void placeBarrierPerimeter(MapTemplate template, BlockBounds start) {
+		BlockPos.Mutable pos = new BlockPos.Mutable();
+
+		pos.setY(start.min().getY() + 2);
+
+		int barrierMinX = start.min().getX() - 1;
+		int barrierMaxX = start.max().getX() + 1;
+
+		int barrierMinZ = start.min().getZ() - 1;
+		int barrierMaxZ = start.max().getZ() + 1;
+
+		for (int x = barrierMinX; x <= barrierMaxX; x += 1) {
+			pos.setX(x);
+
+			pos.setZ(barrierMinZ);
+			template.setBlockState(pos, BARRIER);
+
+			pos.setZ(barrierMaxZ);
+			template.setBlockState(pos, BARRIER);
+		}
+
+		for (int z = barrierMinZ + 1; z <= barrierMaxZ - 1; z += 1) {
+			pos.setZ(z);
+
+			pos.setX(barrierMinX);
+			template.setBlockState(pos, BARRIER);
+
+			pos.setX(barrierMaxX);
+			template.setBlockState(pos, BARRIER);
+		}
+	}
+
 	public MinefieldMap create() {
 		MapTemplate template = MapTemplate.createEmpty();
 		MinefieldMapConfig mapConfig = this.config.getMapConfig();
@@ -51,6 +84,8 @@ public MinefieldMap create() {
 			}
 		}
 
+		this.placeBarrierPerimeter(template, start);
+
 		return new MinefieldMap(template, start, end, guideTextPos);
 	}
 }

src/main/java/io/github/haykam821/minefield/game/phase/MinefieldActivePhase.java

@@ -101,12 +101,13 @@ private void enable() {
 
  		for (ServerPlayerEntity player : this.players) {
 			player.changeGameMode(GameMode.ADVENTURE);
-			this.map.spawn(player, this.world);
 
 			if (!this.singleplayer && this.statistics != null) {
 				this.statistics.forPlayer(player).increment(StatisticKeys.GAMES_PLAYED, 1);
 			}
 		}
+
+		this.map.removeBarrierPerimeter(this.world);
 	}
 
 	private void tick() {

src/main/java/io/github/haykam821/minefield/game/phase/MinefieldWaitingPhase.java

@@ -80,7 +80,7 @@ private void enable() {
 
 	private void tick() {
 		for (ServerPlayerEntity player : this.gameSpace.getPlayers()) {
-			if (this.map.isBelowPlatform(player)) {
+			if (!this.map.isInSpawn(player)) {
 				this.map.spawn(player, this.world);
 			}
 		}