Linked GravityModel to a WorldGenerator and added GM comms transfer

- WorldData no longer acquires a GravityModel automatically
- On the server, GravityModel is specified by WorldGenerator
- On the client, GravityModel is received from the server via a
PacketSetGravityModel

src/main/java/ru/windcorp/progressia/common/world/PacketSetGravityModel.java

@@ -0,0 +1,56 @@
+/*
+ * Progressia
+ * Copyright (C)  2020-2021  Wind Corporation and contributors
+ *
+ * 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 ru.windcorp.progressia.common.world;
+
+import java.io.DataInput;
+import java.io.DataOutput;
+import java.io.IOException;
+
+public class PacketSetGravityModel extends PacketAffectWorld {
+	
+	private String gravityModelId;
+	
+	public PacketSetGravityModel() {
+		this("Core:SetGravityModel");
+	}
+
+	protected PacketSetGravityModel(String id) {
+		super(id);
+	}
+	
+	public void set(GravityModel model) {
+		this.gravityModelId = model.getId();
+	}
+
+	@Override
+	public void read(DataInput input) throws IOException, DecodingException {
+		gravityModelId = input.readUTF();
+	}
+
+	@Override
+	public void write(DataOutput output) throws IOException {
+		output.writeUTF(gravityModelId);
+	}
+
+	@Override
+	public void apply(WorldData world) {
+		GravityModel model = GravityModelRegistry.getInstance().get(gravityModelId);
+		world.setGravityModel(model);
+	}
+
+}

src/main/java/ru/windcorp/progressia/common/world/WorldData.java

@@ -52,7 +52,7 @@ public class WorldData
 
 	private final Collection<EntityData> entities = Collections.unmodifiableCollection(entitiesById.valueCollection());
 
-	private GravityModel gravityModel = GravityModelRegistry.getInstance().get("Test:TheGravityModel");
+	private GravityModel gravityModel = null;
 
 	private float time = 0;
 
@@ -214,6 +214,13 @@ public class WorldData
 	 * @param gravityModel the gravity model to set
 	 */
 	public void setGravityModel(GravityModel gravityModel) {
+		if (!chunks.isEmpty()) {
+			throw new IllegalStateException(
+				"Attempted to change gravity model to " + gravityModel + " while " + chunks.size()
+					+ " chunks were loaded"
+			);
+		}
+
 		this.gravityModel = gravityModel;
 	}
 

src/main/java/ru/windcorp/progressia/server/comms/ClientManager.java

@@ -28,6 +28,7 @@ import gnu.trove.map.TIntObjectMap;
 import gnu.trove.map.hash.TIntObjectHashMap;
 import ru.windcorp.progressia.common.comms.CommsChannel.State;
 import ru.windcorp.progressia.common.comms.packets.Packet;
+import ru.windcorp.progressia.common.world.PacketSetGravityModel;
 import ru.windcorp.progressia.common.world.PacketSetLocalPlayer;
 import ru.windcorp.progressia.common.world.entity.EntityData;
 import ru.windcorp.progressia.server.Player;
@@ -74,6 +75,10 @@ public class ClientManager {
 	private void addClientPlayer(ClientPlayer client) {
 		String login = client.getLogin();
 		
+		PacketSetGravityModel setGravityModelPacket = new PacketSetGravityModel();
+		setGravityModelPacket.set(getServer().getWorld().getData().getGravityModel());
+		client.sendPacket(setGravityModelPacket);
+
 		EntityData entity = getServer().getPlayerManager().conjurePlayerEntity(login);
 		Player player = new Player(entity, getServer(), client);
 		getServer().getPlayerManager().getPlayers().add(player);

src/main/java/ru/windcorp/progressia/server/world/WorldLogic.java

@@ -55,7 +55,9 @@ public class WorldLogic
 	public WorldLogic(WorldData data, Server server, Function<WorldLogic, WorldGenerator> worldGeneratorConstructor) {
 		this.data = data;
 		this.server = server;
+		
 		this.generator = worldGeneratorConstructor.apply(this);
+		data.setGravityModel(getGenerator().getGravityModel());
 
 		data.addListener(new WorldDataListener() {
 			@Override

src/main/java/ru/windcorp/progressia/server/world/generation/AbstractWorldGenerator.java

@@ -25,14 +25,23 @@ import java.util.Objects;
 
 import ru.windcorp.progressia.common.world.ChunkData;
 import ru.windcorp.progressia.common.world.DecodingException;
+import ru.windcorp.progressia.common.world.GravityModel;
+import ru.windcorp.progressia.common.world.GravityModelRegistry;
 
 public abstract class AbstractWorldGenerator<H> extends WorldGenerator {
 
 	private final Class<H> hintClass;
 	
-	public AbstractWorldGenerator(String id, Class<H> hintClass) {
+	private final GravityModel gravityModel;
+
+	public AbstractWorldGenerator(String id, Class<H> hintClass, String gravityModelId) {
 		super(id);
 		this.hintClass = Objects.requireNonNull(hintClass, "hintClass");
+		this.gravityModel = GravityModelRegistry.getInstance().get(Objects.requireNonNull(gravityModelId, "gravityModelId"));
+		
+		if (this.gravityModel == null) {
+			throw new IllegalArgumentException("Gravity model with ID \"" + gravityModelId + "\" not found");
+		}
 	}
 
 	@Override
@@ -64,4 +73,9 @@ public abstract class AbstractWorldGenerator<H> extends WorldGenerator {
 		chunk.setGenerationHint(hint);
 	}
 	
+	@Override
+	public GravityModel getGravityModel() {
+		return gravityModel;
+	}
+
 }

src/main/java/ru/windcorp/progressia/server/world/generation/WorldGenerator.java

@@ -26,6 +26,7 @@ import glm.vec._3.i.Vec3i;
 import ru.windcorp.progressia.common.util.namespaces.Namespaced;
 import ru.windcorp.progressia.common.world.ChunkData;
 import ru.windcorp.progressia.common.world.DecodingException;
+import ru.windcorp.progressia.common.world.GravityModel;
 import ru.windcorp.progressia.common.world.WorldData;
 
 public abstract class WorldGenerator extends Namespaced {
@@ -43,4 +44,6 @@ public abstract class WorldGenerator extends Namespaced {
 
 	public abstract boolean isChunkReady(Object hint);
 	
+	public abstract GravityModel getGravityModel();
+
 }

src/main/java/ru/windcorp/progressia/test/gen/TestWorldGenerator.java

@@ -44,7 +44,7 @@ public class TestWorldGenerator extends AbstractWorldGenerator<Boolean> {
 	private final TestTerrainGenerator terrainGen;
 
 	public TestWorldGenerator(WorldLogic world) {
-		super("Test:WorldGenerator", Boolean.class);
+		super("Test:WorldGenerator", Boolean.class, "Test:TheGravityModel");
 		this.terrainGen = new TestTerrainGenerator(this, world);
 
 		world.getData().addListener(new WorldDataListener() {