Fix update_entity_position and fix writing of Angles to client. (#490)

* update_entity_position sends Entity Position packet instead of Teleport Entity packet.

* Wraps angles correctly.

Author: Tracreed

feather/protocol/src/io.rs

@@ -833,7 +833,11 @@ impl Readable for Angle {
 
 impl Writeable for Angle {
     fn write(&self, buffer: &mut Vec<u8>, version: ProtocolVersion) -> anyhow::Result<()> {
-        let val = (self.0 / 360.0 * 256.0).round() as u8;
+        let temp = (256.0 / 360.0) * (self.0 % 360.0);
+        // Wrap negative values 'x' in the range [-256.0 to 0] to the
+        // correct angle in the range [0 to 256.0 ) by changing 'x' to
+        // x = 256.0 - x
+        let val = ((temp + 256.0) % 256.0) as u8;
         val.write(buffer, version)?;
 
         Ok(())

feather/server/src/client.rs

@@ -18,22 +18,26 @@ use common::{
     Window,
 };
 use packets::server::{Particle, SetSlot, SpawnLivingEntity, UpdateLight, WindowConfirmation};
-use protocol::packets::server::{HeldItemChange, PlayerAbilities};
+use protocol::packets::server::{
+    EntityPosition, EntityPositionAndRotation, HeldItemChange, PlayerAbilities,
+};
 use protocol::{
     packets::{
         self,
         server::{
             AddPlayer, Animation, BlockChange, ChatPosition, ChunkData, ChunkDataKind,
-            DestroyEntities, Disconnect, EntityAnimation, EntityHeadLook, EntityTeleport, JoinGame,
-            KeepAlive, PlayerInfo, PlayerPositionAndLook, PluginMessage, SendEntityMetadata,
-            SpawnPlayer, Title, UnloadChunk, UpdateViewPosition, WindowItems,
+            DestroyEntities, Disconnect, EntityAnimation, EntityHeadLook, JoinGame, KeepAlive,
+            PlayerInfo, PlayerPositionAndLook, PluginMessage, SendEntityMetadata, SpawnPlayer,
+            Title, UnloadChunk, UpdateViewPosition, WindowItems,
         },
     },
     ClientPlayPacket, Nbt, ProtocolVersion, ServerPlayPacket, Writeable,
 };
 use quill_common::components::{OnGround, PreviousGamemode};
 
-use crate::{initial_handler::NewPlayer, network_id_registry::NetworkId, Options};
+use crate::{
+    entities::PreviousPosition, initial_handler::NewPlayer, network_id_registry::NetworkId, Options,
+};
 use slab::Slab;
 
 /// Max number of chunks to send to a client per tick.
@@ -379,6 +383,7 @@ impl Client {
         &self,
         network_id: NetworkId,
         position: Position,
+        prev_position: PreviousPosition,
         on_ground: OnGround,
     ) {
         if self.network_id == Some(network_id) {
@@ -390,23 +395,35 @@ impl Client {
             }
             return;
         }
-        // Consider using the relative movement packets in the future.
-        // (Entity Teleport works fine, but the relative movement packets
-        // save bandwidth.)
-        self.send_packet(EntityTeleport {
-            entity_id: network_id.0,
-            x: position.x,
-            y: position.y,
-            z: position.z,
-            yaw: position.yaw,
-            pitch: position.pitch,
-            on_ground: on_ground.0,
-        });
-        // Needed for head orientation
-        self.send_packet(EntityHeadLook {
-            entity_id: network_id.0,
-            head_yaw: position.yaw,
-        });
+
+        let no_change_yaw = (position.yaw - prev_position.0.yaw).abs() < 0.001;
+        let no_change_pitch = (position.pitch - prev_position.0.pitch).abs() < 0.001;
+
+        if no_change_yaw && no_change_pitch {
+            self.send_packet(EntityPosition {
+                entity_id: network_id.0,
+                delta_x: ((position.x * 32.0 - prev_position.0.x * 32.0) * 128.0) as i16,
+                delta_y: ((position.y * 32.0 - prev_position.0.y * 32.0) * 128.0) as i16,
+                delta_z: ((position.z * 32.0 - prev_position.0.z * 32.0) * 128.0) as i16,
+                on_ground: on_ground.0,
+            });
+        } else {
+            self.send_packet(EntityPositionAndRotation {
+                entity_id: network_id.0,
+                delta_x: ((position.x * 32.0 - prev_position.0.x * 32.0) * 128.0) as i16,
+                delta_y: ((position.y * 32.0 - prev_position.0.y * 32.0) * 128.0) as i16,
+                delta_z: ((position.z * 32.0 - prev_position.0.z * 32.0) * 128.0) as i16,
+                yaw: position.yaw,
+                pitch: position.pitch,
+                on_ground: on_ground.0,
+            });
+
+            // Needed for head orientation
+            self.send_packet(EntityHeadLook {
+                entity_id: network_id.0,
+                head_yaw: position.yaw,
+            });
+        }
     }
 
     pub fn send_keepalive(&self) {

feather/server/src/systems/entity.rs

@@ -24,7 +24,7 @@ fn send_entity_movement(game: &mut Game, server: &mut Server) -> SysResult {
     {
         if position != prev_position.0 {
             server.broadcast_nearby_with(position, |client| {
-                client.update_entity_position(network_id, position, on_ground);
+                client.update_entity_position(network_id, position, *prev_position, on_ground);
             });
             prev_position.0 = position;
         }