diff --git a/choco.lua b/choco.lua
index a124595..a632e7f 100644
--- a/choco.lua
+++ b/choco.lua
@@ -1,10 +1,10 @@
 function _init()
+  world_init()
   playercontroler_init()
-  worldtiles = {}
 end
  
 function _update()
-  if (btnp(5)) compute_effect_array(worldtiles)
+  world_update()
   playercontroler_update()
 end
  
@@ -12,7 +12,37 @@ function _draw()
   cls(0)
   map(0, 0, 0, 8, 64, 64) 
   camera(0,0)
-  draw_array(worldtiles)
   draw_ressource_bar()
+  world_draw()
   playercontroler_draw()
+end
+
+ressources = 
+{
+  fruit = 
+  {
+    quantity = 55,
+    sprite = 33,
+    x = 70
+  },
+  money =
+  {
+    quantity = 100,
+    sprite = 35,
+    x = 0
+  },
+  jam =
+  {
+    quantity = 100,
+    sprite = 34,
+    x = 100
+  }
+}
+
+function draw_ressource_bar()
+  rectfill(0, 0, 127, 7, 1)
+  for _,res in pairs(ressources) do
+    spr(res.sprite, res.x, 0)
+    print(res.quantity, res.x + 8, 1, 6)
+  end
 end
\ No newline at end of file
diff --git a/world.lua b/world.lua
index 3101de0..66e4fa3 100644
--- a/world.lua
+++ b/world.lua
@@ -1,57 +1,62 @@
+function world_init()
+  worldtiles = {}
+  --test start
+  bob = build(3,2,buildings.jam_workshop)
+  bob = replace(bob, buildings.city)
+  destroy(bob)
+  --test end
+end
 
-ressources = 
+function world_update()
+    if (btnp(4)) build(3,2,buildings.jam_workshop)
+    if (btnp(5)) compute_effect_array(worldtiles)
+end
+
+function world_draw()
+  draw_array(worldtiles)
+end
+
+
+buildings = 
 {
-  fruits = 
-  {
-    quantity = 5,
-    sprite = 33,
-    x = 70
-  },
-  money =
-  {
-    quantity = 100,
-    sprite = 35,
-    x = 0
-  },
-  jam =
-  {
-    quantity = 0,
-    sprite = 34,
-    x = 100
-  }
-}
-
-buildings = {
   jam_workshop = 
   {
     sprite = 1,
-    inputs = {
-      {fruit = 2}
+    inputs = 
+    {
+        {
+            type = "fruit",
+            quantity = 2
+        }
     },
-    outputs = {jam = 3}
+    outputs = 
+    {
+        {
+            type = "jam",
+            quantity = 3
+        }
+    }
   },
   city = 
   {
     sprite = 5,
-    inputs = {},
-    outputs = {}
+    inputs = 
+    {
+        {
+            type = "jam",
+            quantity = 1
+        }
+    },
+    outputs = 
+    {
+        {
+            type = "money",
+            quantity = 2
+        }
+    }
   },
 }
 
-
-function draw_ressource_bar()
-  rectfill(0, 0, 127, 7, 1)
-  for _,res in pairs(ressources) do
-    spr(res.sprite, res.x, 0)
-    print(res.quantity, res.x + 8, 1, 6)
-  end
-end
-
-          
-function updatecycle()
-
-end
-
 function compute_effect_array(array)
   for obj in all(array) do
     obj.compute_effet(obj)
@@ -64,20 +69,50 @@ function draw_array(array)
   end
 end
 
-
-
 function new_worldtile(x, y, building)
     local worldtile = {}
     worldtile.x = x
     worldtile.y = y
     worldtile.building = building
     worldtile.draw = function(this)
-      spr(worldtile.bulding.sprite,worldtile.x*2*8,8+worldtile.y*2*8, 2, 2)
+      spr(worldtile.building.sprite,worldtile.x*2*8,8+worldtile.y*2*8, 2, 2)
     end
     worldtile.compute_effet = function(this)
+        has_ressource = true
         for _,input in pairs(worldtile.building.inputs) do
-          --input.
+          if (ressources[input.type].quantity < input.quantity) has_ressource = false
+        end
+        if (has_ressource) then
+            for _,input in pairs(worldtile.building.inputs) do
+                ressources[input.type].quantity-=input.quantity
+            end
+            for _,output in pairs(worldtile.building.outputs) do
+                ressources[output.type].quantity+=output.quantity
+            end
         end
     end
     return worldtile
 end
+
+function build(x, y, building)
+    newtile = new_worldtile(x,y,building)
+    add(worldtiles, newtile)
+    return newtile
+end
+
+function destroy(worldtile)
+    del(worldtiles, worldtile)
+end
+
+function replace(worldtile, building)
+    destroy(worldtile)
+    return build(worldtile.x, worldtile.y, building)
+end
+
+function get_worldtile(x,y)
+    for _,tile in pairs(worldtiles) do
+        if (tile.x == x and tile.y == y) then 
+            return tile
+        end
+    end
+end