Axis pair unit vectors

CHANGELOG.md

@@ -18,6 +18,13 @@
   * `Hex::NEG_Z`
   * `Hex::AXES`
   * `Hex::AXES`
+* Added axis pair consts as:
+  * `Hex::INCR_X`
+  * `Hex::INCR_Y
+  * `Hex::INCR_Z`
+  * `Hex::DECR_X`
+  * `Hex::DECR_Y
+  * `Hex::DECR_Z`
 
 ## 0.16.1
 

src/hex/mod.rs

@@ -102,6 +102,20 @@ impl Hex {
     /// -Y (-R) (0, -1)
     pub const NEG_Y: Self = Self::new(0, -1);
 
+    /// Unit vectors that increase the X axis in clockwise order
+    pub const INCR_X: [Self; 2] = [Self::new(1, 0), Self::new(1, -1)];
+    /// Unit vectors that increase the Y axis in clockwise order
+    pub const INCR_Y: [Self; 2] = [Self::new(0, 1), Self::new(-1, 1)];
+    /// Unit vectors that increase the Z axis in clockwise order
+    pub const INCR_Z: [Self; 2] = [Self::new(-1, 0), Self::new(0, -1)];
+
+    /// Unit vectors that decrease the X axis in clockwise order
+    pub const DECR_X: [Self; 2] = [Self::new(-1, 0), Self::new(-1, 1)];
+    /// Unit vectors that decrease the Y axis in clockwise order
+    pub const DECR_Y: [Self; 2] = [Self::new(0, -1), Self::new(1, -1)];
+    /// Unit vectors that decrease the Z axis in clockwise order
+    pub const DECR_Z: [Self; 2] = [Self::new(1, 0), Self::new(0, 1)];
+
     /// Hexagon edge neighbor coordinates array, following [`EdgeDirection`]
     /// order
     ///
@@ -118,6 +132,23 @@ impl Hex {
     ///           \___/
     ///       Y           -Z
     /// ```
+    ///
+    /// Cubic coordinates:
+    ///
+    /// ```txt
+    ///              (0, -1, 1)
+    ///                  ___
+    ///                 /   \
+    ///  (-1, 0, 1) +--+  4  +--+ (1, -1, 0)
+    ///            / 3  \___/  5 \
+    ///            \    /   \    /
+    ///             +--+     +--+
+    ///            /    \___/    \
+    /// (-1, 1, 0) \ 2  /   \  0 / (1, 0, -1)
+    ///             +--+  1  +--+
+    ///                 \___/
+    ///               (0, 1, -1)
+    /// ```
     pub const NEIGHBORS_COORDS: [Self; 6] = [
         Self::new(1, 0),
         Self::new(0, 1),

src/hex/tests.rs

@@ -528,3 +528,19 @@ fn resolutions() {
         }
     }
 }
+
+#[test]
+fn axis_pairs() {
+    for [[a, b], [na, nb]] in [
+        [Hex::INCR_X, Hex::DECR_X],
+        [Hex::INCR_Y, Hex::DECR_Y],
+        [Hex::INCR_Z, Hex::DECR_Z],
+    ] {
+        assert_eq!(a.length(), 1);
+        assert_eq!(b.length(), 1);
+        assert_eq!(na.length(), 1);
+        assert_eq!(nb.length(), 1);
+        assert_eq!(a.const_neg(), na);
+        assert_eq!(b.const_neg(), nb);
+    }
+}