Sneaking (#237)

* start implementing sneaking

* fix horizontal_collision being inverted and cleanup

* clippy

* change dimensions and eye height based on pose

* proper support for automatically crouching in certain cases

* fix anticheat issues

* add line to changelog and update a comment

1 files changed, 67 insertions, 0 deletions

diff --git a/azalea-physics/src/local_player.rs b/azalea-physics/src/local_player.rs
new file mode 100644
index 00000000..6ce196b6
--- /dev/null
+++ b/azalea-physics/src/local_player.rs
@@ -0,0 +1,67 @@
+use azalea_core::position::Vec2;
+use bevy_ecs::component::Component;
+
+/// Component for entities that can move and sprint. Usually only in
+/// [`LocalEntity`]s.
+///
+/// [`LocalEntity`]: azalea_entity::LocalEntity
+#[derive(Default, Component, Clone)]
+pub struct PhysicsState {
+    /// Minecraft only sends a movement packet either after 20 ticks or if the
+    /// player moved enough. This is that tick counter.
+    pub position_remainder: u32,
+    pub was_sprinting: bool,
+    // Whether we're going to try to start sprinting this tick. Equivalent to
+    // holding down ctrl for a tick.
+    pub trying_to_sprint: bool,
+
+    /// Whether our player is currently trying to sneak.
+    ///
+    /// This is distinct from
+    /// [`AbstractEntityShiftKeyDown`](azalea_entity::metadata::AbstractEntityShiftKeyDown),
+    /// which is a metadata value that is controlled by the server and affects
+    /// how the nametags of other entities are displayed.
+    ///
+    /// To check whether we're actually sneaking, you can check the
+    /// [`Crouching`] or [`Pose`] components.
+    pub trying_to_crouch: bool,
+
+    pub move_direction: WalkDirection,
+    pub move_vector: Vec2,
+}
+
+/// A direction that a player can walk in, including none.
+///
+/// Superset of [`SprintDirection`].
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
+pub enum WalkDirection {
+    #[default]
+    None,
+    Forward,
+    Backward,
+    Left,
+    Right,
+    ForwardRight,
+    ForwardLeft,
+    BackwardRight,
+    BackwardLeft,
+}
+
+/// The directions that a player can sprint in. It's a subset of
+/// [`WalkDirection`].
+#[derive(Clone, Copy, Debug)]
+pub enum SprintDirection {
+    Forward,
+    ForwardRight,
+    ForwardLeft,
+}
+
+impl From<SprintDirection> for WalkDirection {
+    fn from(d: SprintDirection) -> Self {
+        match d {
+            SprintDirection::Forward => WalkDirection::Forward,
+            SprintDirection::ForwardRight => WalkDirection::ForwardRight,
+            SprintDirection::ForwardLeft => WalkDirection::ForwardLeft,
+        }
+    }
+}