dungeon: add FPos for decimial positions

1 files changed, 142 insertions, 0 deletions

diff --git a/dungeon/src/pos.rs b/dungeon/src/pos.rs
index 4947ce2..dc1bd2d 100644
--- a/dungeon/src/pos.rs
+++ b/dungeon/src/pos.rs
@@ -2,6 +2,8 @@
 //! entity or objects position and facing direction inside the
 //! dungeon grid.
 
+use std::ops::{AddAssign, SubAssign};
+
 use crate::{MAP_SIZE_USIZE, map::MAP_SIZE};
 
 macro_rules! downcast {
@@ -253,3 +255,143 @@ impl Default for Pos {
 		const_pos!(0, 0)
 	}
 }
+impl TryFrom<usize> for Pos {
+	type Error = ();
+
+	fn try_from(value: usize) -> Result<Self, Self::Error> {
+		Self::from_idx(value).ok_or(())
+	}
+}
+
+/// The `FPos` type represents a floating 2D (temp) position.
+///
+/// This position is not gurenteed to be inside the dungeon grid. FPos exists to
+/// tween between two different `Pos`. All bounds checks should be done in `Pos` before updating
+/// the underlying Floating Position.
+#[derive(Clone, Copy, Debug, PartialEq, PartialOrd)]
+pub struct FPos(f32, f32);
+impl FPos {
+	/// Creates a new position from a given floating x and y position.
+	///
+	/// Returns `None` if the position goes out of the map.
+	///
+	/// # Examples
+	///
+	/// ```
+	/// use dungeon::FPos;
+	///
+	/// let fpos = FPos::new(5.4,6.7);
+	/// ```
+	#[must_use]
+	pub const fn new(x: f32, y: f32) -> Self {
+		Self(x, y)
+	}
+
+	/// Creates a new `FPos` using the checked/fixed `Pos`.
+	///
+	/// # Examples
+	///
+	/// ```
+	/// use dungeon::{Pos, FPos};
+	///
+	/// let pos = Pos::new(1, 1).unwrap();
+	/// let fpos = FPos::from_pos(pos);
+	/// ```
+	#[must_use]
+	pub const fn from_pos(pos: Pos) -> Self {
+		let (x, y) = pos.xy();
+		Self(x as f32, y as f32)
+	}
+
+	/// Returns the x and y positions of `FPos`.
+	///
+	/// # Examples
+	///
+	/// ```
+	/// use dungeon::FPos;
+	///
+	/// let fpos = FPos::new(5.0,7.2);
+	/// let (x,y) = fpos.xy();
+	/// assert_eq!(x, 5.0);
+	/// assert_eq!(y, 7.2);
+	/// ```
+	#[must_use]
+	pub const fn xy(self) -> (f32, f32) {
+		(self.0, self.1)
+	}
+
+	/// Steps `FPos` a given floating amount in the `Direction` `dir`.
+	///
+	/// Returns `None` if the floating position wraps.
+	///
+	/// # Examples
+	///
+	/// ```
+	/// use dungeon::{Direction, FPos};
+	///
+	/// let fpos = FPos::new(0.0, 1.0);
+	/// let new_fpos = fpos.step(Direction::North, 0.3);
+	/// assert!(new_fpos.is_some());
+	/// ```
+	///
+	/// ```
+	/// use dungeon::{Direction, FPos};
+	///
+	/// let fpos = FPos::new(0.0, 0.0);
+	/// let new_fpos = fpos.step(Direction::North, 5.0);
+	/// assert!(new_fpos.is_none());
+	/// ```
+	#[must_use]
+	pub fn step(self, dir: Direction, amt: f32) -> Option<Self> {
+		use Direction as D;
+		let (mut x, mut y) = self.xy();
+		match dir {
+			D::North if y >= amt => y.sub_assign(amt),
+			D::South => y.add_assign(amt),
+			D::East => x.add_assign(amt),
+			D::West if x >= amt => x.sub_assign(amt),
+			_ => return None,
+		};
+		Some(Self(x, y))
+	}
+
+	/// Computes the absolute difference between to positions
+	///
+	/// # Examples
+	///
+	/// ```
+	/// use dungeon::FPos;
+	///
+	/// let fpos1 = FPos::new(1.0,0.0);
+	/// let fpos2 = FPos::new(0.0,1.0);
+	/// let diff = fpos1.abs_diff(fpos2);
+	/// assert_eq!(diff.xy(), (1.0, 1.0));
+	/// ```
+	///
+	#[must_use]
+	pub fn abs_diff(self, other: Self) -> Self {
+		let x = (self.0 - other.0).abs();
+		let y = (self.1 - other.1).abs();
+		Self(x, y)
+	}
+}
+impl Default for FPos {
+	/// Returns a default postion at the origin (0,0)
+	///
+	/// ```
+	/// use dungeon::FPos;
+	///
+	/// let fpos = FPos::default();
+	///
+	/// assert_eq!(fpos.xy(), (0.0, 0.0));
+	/// ```
+	///
+	fn default() -> Self {
+		Self::new(0.0, 0.0)
+	}
+}
+impl From<Pos> for FPos {
+	fn from(value: Pos) -> Self {
+		Self::from_pos(value)
+	}
+}