Implement EntityPositionSync (#196)

* implement EntityPositionSync

* fix EntityPositionSync setting the wrong vec_delta_codec and also move into a RelativeEntityUpdate

1 files changed, 60 insertions, 0 deletions

diff --git a/azalea-entity/src/vec_delta_codec.rs b/azalea-entity/src/vec_delta_codec.rs
new file mode 100644
index 00000000..51aa7cea
--- /dev/null
+++ b/azalea-entity/src/vec_delta_codec.rs
@@ -0,0 +1,60 @@
+use azalea_core::position::Vec3;
+
+#[derive(Debug, Clone, Default)]
+pub struct VecDeltaCodec {
+    base: Vec3,
+}
+
+impl VecDeltaCodec {
+    pub fn new(base: Vec3) -> Self {
+        Self { base }
+    }
+
+    pub fn decode(&self, x: i64, y: i64, z: i64) -> Vec3 {
+        if x == 0 && y == 0 && z == 0 {
+            return self.base;
+        }
+
+        let new_x = if x == 0 {
+            self.base.x
+        } else {
+            decode(encode(self.base.x) + x)
+        };
+        let new_y = if y == 0 {
+            self.base.y
+        } else {
+            decode(encode(self.base.y) + y)
+        };
+        let new_z = if z == 0 {
+            self.base.z
+        } else {
+            decode(encode(self.base.z) + z)
+        };
+
+        Vec3::new(new_x, new_y, new_z)
+    }
+
+    pub fn encode_x(&self, pos: Vec3) -> i64 {
+        encode(pos.x) - encode(self.base.x)
+    }
+    pub fn encode_y(&self, pos: Vec3) -> i64 {
+        encode(pos.y) - encode(self.base.y)
+    }
+    pub fn encode_z(&self, pos: Vec3) -> i64 {
+        encode(pos.z) - encode(self.base.z)
+    }
+
+    pub fn set_base(&mut self, pos: Vec3) {
+        self.base = pos;
+    }
+    pub fn base(&self) -> Vec3 {
+        self.base
+    }
+}
+
+fn encode(value: f64) -> i64 {
+    (value * 4096.).round() as i64
+}
+fn decode(value: i64) -> f64 {
+    (value as f64) / 4096.
+}