Pathfinder (#25)

Pathfinding is very much not done, but it works enough and I want to get this merged.
TODO: fast replanning, goals that aren't a single node, falling moves (it should be able to play the dropper), parkour moves

1 files changed, 116 insertions, 0 deletions

diff --git a/azalea-world/src/entity/attributes.rs b/azalea-world/src/entity/attributes.rs
new file mode 100644
index 00000000..1050615c
--- /dev/null
+++ b/azalea-world/src/entity/attributes.rs
@@ -0,0 +1,116 @@
+//! https://minecraft.fandom.com/wiki/Attribute
+
+use std::{
+    collections::HashMap,
+    io::{Cursor, Write},
+};
+
+use azalea_buf::{BufReadError, McBuf, McBufReadable, McBufWritable};
+use thiserror::Error;
+use uuid::{uuid, Uuid};
+
+#[derive(Clone, Debug)]
+pub struct AttributeModifiers {
+    pub speed: AttributeInstance,
+}
+
+#[derive(Clone, Debug)]
+pub struct AttributeInstance {
+    pub base: f64,
+    modifiers_by_uuid: HashMap<Uuid, AttributeModifier>,
+}
+
+#[derive(Clone, Debug, Error)]
+#[error("A modifier with this UUID is already present.")]
+pub struct AlreadyPresentError;
+
+impl AttributeInstance {
+    pub fn new(base: f64) -> Self {
+        Self {
+            base,
+            modifiers_by_uuid: HashMap::new(),
+        }
+    }
+
+    pub fn calculate(&self) -> f64 {
+        let mut total = self.base;
+        for modifier in self.modifiers_by_uuid.values() {
+            match modifier.operation {
+                AttributeModifierOperation::Addition => total += modifier.amount,
+                AttributeModifierOperation::MultiplyBase => total += self.base * modifier.amount,
+                _ => {}
+            }
+            match modifier.operation {
+                AttributeModifierOperation::MultiplyTotal => total *= 1.0 + modifier.amount,
+                _ => {}
+            }
+        }
+        total
+    }
+
+    /// Add a new modifier to this attribute.
+    pub fn insert(&mut self, modifier: AttributeModifier) -> Result<(), AlreadyPresentError> {
+        if self
+            .modifiers_by_uuid
+            .insert(modifier.uuid, modifier)
+            .is_some()
+        {
+            Err(AlreadyPresentError)
+        } else {
+            Ok(())
+        }
+    }
+
+    /// Remove the modifier with the given UUID from this attribute, returning
+    /// the previous modifier is present.
+    pub fn remove(&mut self, uuid: &Uuid) -> Option<AttributeModifier> {
+        self.modifiers_by_uuid.remove(uuid)
+    }
+}
+
+#[derive(Clone, Debug)]
+pub struct AttributeModifier {
+    pub uuid: Uuid,
+    pub name: String,
+    pub amount: f64,
+    pub operation: AttributeModifierOperation,
+}
+
+#[derive(Clone, Debug, Copy, McBuf)]
+pub enum AttributeModifierOperation {
+    Addition,
+    MultiplyBase,
+    MultiplyTotal,
+}
+
+pub fn sprinting_modifier() -> AttributeModifier {
+    AttributeModifier {
+        uuid: uuid!("662A6B8D-DA3E-4C1C-8813-96EA6097278D"),
+        name: "Sprinting speed boost".to_string(),
+        amount: 0.30000001192092896,
+        operation: AttributeModifierOperation::MultiplyTotal,
+    }
+}
+
+impl McBufReadable for AttributeModifier {
+    fn read_from(buf: &mut Cursor<&[u8]>) -> Result<Self, BufReadError> {
+        let uuid = Uuid::read_from(buf)?;
+        let amount = f64::read_from(buf)?;
+        let operation = AttributeModifierOperation::read_from(buf)?;
+        Ok(Self {
+            uuid,
+            name: "Unknown synced attribute modifier".to_string(),
+            amount,
+            operation,
+        })
+    }
+}
+
+impl McBufWritable for AttributeModifier {
+    fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
+        self.uuid.write_into(buf)?;
+        self.amount.write_into(buf)?;
+        self.operation.write_into(buf)?;
+        Ok(())
+    }
+}