Add position.lerp

Author: raiguard

changelog.txt

@@ -2,7 +2,7 @@
 Version: 0.13.0
 Date: ????
   Features:
-    - [position] Added `position.ge` and `position.gt` comparisons.
+    - [position] Added `position.ge`, `position.gt`, and `position.lerp` functions.
   Bugfixes:
     - [bounding-box] Fixed `bounding_box.recenter_on()` not properly preserving box dimensions.
 ---------------------------------------------------------------------------------------------------

position.lua

@@ -1,3 +1,5 @@
+local flib_math = require("__flib__/math")
+
 --- Utilities for manipulating positions. All functions support both the shorthand and explicit syntaxes and will
 --- preserve the syntax that was passed in.
 --- ```lua
@@ -180,6 +182,20 @@ function flib_position.le(pos1, pos2)
   return x1 <= x2 and y1 <= y2
 end
 
+--- Linearly interpolate between two positions. For example, an amount of 0.5 will return the midpoint.
+--- @generic P
+--- @param pos1 P
+--- @param pos2 P
+--- @param amount number
+--- @return P
+function flib_position.lerp(pos1, pos2, amount)
+  if pos1.x then
+    return { x = flib_math.lerp(pos1.x, pos2.x, amount), y = flib_math.lerp(pos1.y, pos2.y, amount) }
+  else
+    return { flib_math.lerp(pos1[1], pos2[1], amount), flib_math.lerp(pos1[2], pos2[2], amount) }
+  end
+end
+
 --- Test if `pos1` is less than `pos2`.
 --- @generic P
 --- @param pos1 P