Add some rudimentary code for facing and collision detection.

movement.lua

@@ -1,14 +1,53 @@
 function init_movement()
    camera_pos = {0, 0}
+
+   -- [1] is vertical facing, [2] is horizontal, -1 is up/left, 0 is neutral,
+   -- and 1 is down/right
+   facing = {1, 0}
+
+   -- this is a constant for looking up player sprites by facing
+   player_lookup = {
+      [{0, 0}] = -1, -- this state is an error
+      [{-1, 0}] = 120, -- up
+      [{1, 0}] = 121, -- down
+      [{0, -1}] = 122, -- left
+      [{0, 1}] = 123, -- right
+      [{-1, -1}] = 124, -- up-left
+      [{-1, 1}] = 125, -- up-right
+      [{1, -1}] = 126, -- down-left
+      [{1, 1}] = 127 -- down-right
+   }
 end
 
 
 function handle_input()
    new_pos = camera_pos
-   if (btnp(0)) new_pos[1] -= 1 -- move left
-   if (btnp(1)) new_pos[1] += 1 -- move right
-   if (btnp(2)) new_pos[2] -= 1 -- move up
-   if (btnp(3)) new_pos[2] += 1 -- move down
+
+   if btnp(0) or btnp(1) or btnp(2) or btnp(3) then
+      if btnp(0) then
+         new_pos[1] -= 1 -- move left
+         facing[2] = -1
+      end
+      if btnp(1) then
+         new_pos[1] += 1 -- move right
+         facing[2] = 1
+      end
+      if not (btnp(0) or btnp(1)) then
+         facing[2] = 0
+      end
+
+      if btnp(2) then
+         new_pos[2] -= 1 -- move up
+         facing[1] = -1
+      end
+      if btnp(3) then
+         new_pos[2] += 1 -- move down
+         facing[1] = 1
+      end
+      if not (btnp(2) or btnp(3)) then
+         facing[1] = 0
+      end
+   end
 
    if legal_move(new_pos) then
       camera_pos = new_pos
@@ -18,9 +57,12 @@ function handle_input()
 end
 
 function draw_player()
-
+   spr(player_lookup[facing], 64, 64)
+   -- todo: animate the character on move
 end
 
+-- pos is a camera position, meaning the player position is
+-- pos + {8, 8}
 function legal_move(pos)
-   return true
+   return fget(mget(pos[1]+8, pos[2]+8), 0)
 end