rotating deer demo

lib/entity.lua

@@ -6,6 +6,9 @@ __Entity = {
     sprite = __AnimatedSprite,
     position = Vec3 {},
     velocity = Vec3 {},
+    direction = 0, -- clockwise radians
+    friction = 0.98,
+    speed = 1
 }
 
 function Entity(id)
@@ -17,7 +20,32 @@ function Entity(id)
 end
 
 function __Entity:update(dt)
+    self:processMovement()
     if self.sprite then
         self.sprite:update(dt)
     end
 end
+
+function __Entity:processMovement()
+    self.position = self.position + self.velocity
+    self.velocity = self.velocity * self.friction
+end
+
+function __Entity:namedDirection()
+    local lookup = {
+        "e",
+        "se",
+        "s",
+        "sw",
+        "w",
+        "nw",
+        "n",
+        "ne"
+    }
+    local idx = math.floor((4 * self.direction / math.pi) + math.pi / 8) % 8
+    return lookup[idx + 1]
+end
+
+function __Entity:lookAt(vec)
+    self.direction = (vec - self.position):direction()
+end

lib/sprite.lua

@@ -31,5 +31,5 @@ function __AnimatedSprite:getTexture()
     if self.playing then
         return self[self.playing].spriteSheet
     end
-    return nil
+    return AssetBundle.files.sprites.fallback
 end

lib/vec3.lua

@@ -1,16 +1,16 @@
 require "lib.option"
 
 __Vec3 = {
-    _x = 0,
+    x = 0,
-    _y = 0,
+    y = 0,
-    _z = 0,
+    z = 0,
 }
 
 function Vec3(vec)
     return setmetatable({
-        _x = vec[1] or 0,
+        x = vec[1] or 0,
-        _y = vec[2] or 0,
+        y = vec[2] or 0,
-        _z = vec[3] or 0,
+        z = vec[3] or 0,
     }, {
         __index = __Vec3,
         __tostring = __Vec3.__tostring,
@@ -19,41 +19,48 @@ function Vec3(vec)
         __unm = function(self)
             return __Vec3.scale(self, -1)
         end,
+        __sub = function(self, other)
+            return self + -other
+        end,
         __eq = function(self, other)
             return
-                self._x == other._x
+                self.x == other.x
-                and self._y == other._y
+                and self.y == other.y
-                and self._z == other._z
+                and self.z == other.z
         end,
     })
 end
 
 function __Vec3:add(other)
-    Vec3 { self._x + other._x, self._y + other._y, self._z + other._z }
+    return Vec3 { self.x + other.x, self.y + other.y, self.z + other.z }
 end
 
 function __Vec3:scale(factor)
-    return Vec3 { self._x * factor, self._y * factor, self._z * factor }
+    return Vec3 { self.x * factor, self.y * factor, self.z * factor }
 end
 
 function __Vec3:length()
-    return math.sqrt(self._x ^ 2 + self._y ^ 2 + self._z ^ 2)
+    return math.sqrt(self.x ^ 2 + self.y ^ 2 + self.z ^ 2)
 end
 
 function __Vec3:normalize()
     local length = self:length()
     if not length then return None end
     return Some(Vec3 {
-        self._x / length,
+        self.x / length,
-        self._y / length,
+        self.y / length,
-        self._z / length
+        self.z / length
     })
 end
 
+function __Vec3:direction()
+    return math.atan2(self.y, self.x)
+end
+
 function __Vec3:dot(other)
-    return self._x * other._x + self._y * other._y + self._z * other._z
+    return self.x * other.x + self.y * other.y + self.z * other.z
 end
 
 function __Vec3:__tostring()
-    return "Vec3{" .. self._x .. ", " .. self._y .. ", " .. self._z .. "}"
+    return "Vec3{" .. self.x .. ", " .. self.y .. ", " .. self.z .. "}"
 end

main.lua

@@ -63,33 +63,34 @@ end
 
 require "lib.asset_bundle"
 require "lib.entity"
+require "lib.vec3"
 
 
 Deer = nil
-local tick = 0
 
 function love.load()
     AssetBundle:load()
     Deer = Entity('deer')
+    Deer.position = Vec3 { 200, 200, 0 }
     Deer.sprite.playing = "walk_e"
 end
 
+local lastDir
 function love.update(dt)
-    Deer:update(dt)
+    local mouse = Vec3 { love.mouse.getPosition() }
-    tick = tick + 1
+    if (mouse) then Deer:lookAt(mouse) end
 
-    if (tick % 100 == 0) then
+    if (lastDir and lastDir ~= Deer:namedDirection()) then
-        if (Deer.sprite.playing == "walk_e") then
+        print(Deer:namedDirection())
-            Deer.sprite.playing = "walk_w"
-        else
-            Deer.sprite.playing = "walk_e"
-        end
-        tick = 0
     end
+
+    lastDir = Deer:namedDirection()
+    Deer:update(dt)
 end
 
 function love.draw()
-    love.graphics.draw(Deer.sprite:getTexture(), Deer.sprite:getQuad(), 200, 200, 0, 4, 4)
+    love.graphics.draw(Deer.sprite:getTexture(), Deer.sprite:getQuad(), Deer.position.x, Deer.position.y, Deer.direction,
+        4, 4, 32, 32)
 end
 
 function love.conf(t)