2 files changed, 61 insertions, 4 deletions
diff --git a/azalea-protocol/src/common/movements.rs b/azalea-protocol/src/common/movements.rs
index ffc3452f..a70342b3 100644
--- a/azalea-protocol/src/common/movements.rs
+++ b/azalea-protocol/src/common/movements.rs
@@ -1,8 +1,11 @@
-use std::io::{self, Cursor, Write};
+use std::{
+    io::{self, Cursor, Write},
+    ops::Add,
+};
 
 use azalea_buf::{AzBuf, AzaleaRead, AzaleaWrite, BufReadError};
-use azalea_core::{bitset::FixedBitSet, position::Vec3};
-use azalea_entity::LookDirection;
+use azalea_core::{bitset::FixedBitSet, math, position::Vec3};
+use azalea_entity::{LookDirection, Physics, Position};
 
 /// The updated position, velocity, and rotations for an entity.
 ///
@@ -32,6 +35,60 @@ impl RelativeMovements {
     pub fn all_absolute() -> Self {
         RelativeMovements::default()
     }
+    pub fn all_relative() -> Self {
+        RelativeMovements {
+            x: true,
+            y: true,
+            z: true,
+            y_rot: true,
+            x_rot: true,
+            delta_x: true,
+            delta_y: true,
+            delta_z: true,
+            rotate_delta: true,
+        }
+    }
+
+    pub fn apply(
+        &self,
+        change: &PositionMoveRotation,
+        position: &mut Position,
+        direction: &mut LookDirection,
+        physics: &mut Physics,
+    ) {
+        let new_position = Vec3::new(
+            apply_change(position.x, self.x, change.pos.x),
+            apply_change(position.y, self.y, change.pos.y),
+            apply_change(position.z, self.z, change.pos.z),
+        );
+
+        let new_look_direction = LookDirection::new(
+            apply_change(direction.y_rot, self.y_rot, change.look_direction.y_rot),
+            apply_change(direction.x_rot, self.x_rot, change.look_direction.x_rot),
+        );
+
+        let mut new_delta = physics.velocity;
+        if self.rotate_delta {
+            let y_rot_delta = direction.y_rot - new_look_direction.y_rot;
+            let x_rot_delta = direction.x_rot - new_look_direction.x_rot;
+            new_delta = new_delta
+                .x_rot(math::to_radians(x_rot_delta as f64) as f32)
+                .y_rot(math::to_radians(y_rot_delta as f64) as f32);
+        }
+        let new_delta = Vec3::new(
+            apply_change(new_delta.x, self.delta_x, change.delta.x),
+            apply_change(new_delta.y, self.delta_y, change.delta.y),
+            apply_change(new_delta.z, self.delta_z, change.delta.z),
+        );
+
+        **position = new_position;
+        *direction = new_look_direction;
+        physics.velocity = new_delta;
+    }
+}
+
+fn apply_change<T: Add<Output = T>>(base: T, condition: bool, change: T) -> T {
+    if condition { base + change } else { change }
 }
 
 impl AzaleaRead for RelativeMovements {
diff --git a/azalea-protocol/src/packets/game/c_teleport_entity.rs b/azalea-protocol/src/packets/game/c_teleport_entity.rs
index 92b8f1eb..e19ded58 100644
--- a/azalea-protocol/src/packets/game/c_teleport_entity.rs
+++ b/azalea-protocol/src/packets/game/c_teleport_entity.rs
@@ -9,6 +9,6 @@ pub struct ClientboundTeleportEntity {
     #[var]
     pub id: MinecraftEntityId,
     pub change: PositionMoveRotation,
-    pub relatives: RelativeMovements,
+    pub relative: RelativeMovements,
     pub on_ground: bool,
 }