Add utility class.

src/enemy/ika.lua

@@ -4,6 +4,7 @@ import "CoreLibs/graphics"
 import "CoreLibs/sprites"
 import "CoreLibs/timer"
 import "entity"
+import "util"
 
 local gfx <const> = playdate.graphics
 local geom <const> = playdate.geometry
@@ -29,9 +30,7 @@ function Ika:onReady()
 end
 
 function Ika:calculateVector(target)
-   local vec = geom.point.new(target:getPosition()) -
-      geom.point.new(self:getPosition())
-   return vec:normalized() * 5
+   return util.unitPointer(self:getPosition(), target:getPosition()) * 5
 end
 
 function Ika:remove()

src/entity.lua

@@ -101,15 +101,15 @@ end
 -- State machine-controlled functions
 
 function Entity:onInit()
-  -- noop
+  -- stub for subclassing
 end
 
 function Entity:runInit()
-  -- noop
+  -- stub for subclassing
 end
 
 function Entity:onIntro()
-   -- noop
+   -- stub for subclassing
 end
 
 function Entity:runIntro()
@@ -121,7 +121,7 @@ function Entity:runIntro()
 end
 
 function Entity:onReady()
-   -- noop
+   -- stub for subclassing
 end
 
 function Entity:runReady()

src/util.lua

@@ -0,0 +1,19 @@
+-- Generic utility functions, because sometimes being lazy is more efficient
+
+import "CoreLibs/graphics"
+
+local geom <const> = playdate.geometry
+
+util = {}
+
+-- creates a unit vector that "points" from point A to point B
+function util.unitPointer(a, b)
+   return (b - a):normalized()
+end
+
+-- create a unit vector that points from x1, y1 to x2, y2
+function util.unitPointer(x1, y1, x2, y2)
+   local a = geom.point.new(x1, y1)
+   local b = geom.point.new(x2, y2)
+   return unitPointer(a,b)
+end