progress on player-enemy collisions when player is attacking enemy

fcore/bin-search.sml

@@ -1,6 +1,24 @@
 structure BinSearch =
 struct
-  local
+  fun helpExists (findNum, vec, low, high) =
+    if high >= low then
+      let
+        val mid = low + ((high - low) div 2)
+        val curNum = Vector.sub (vec, mid)
+      in
+        if curNum = findNum then
+          true
+        else if curNum < findNum then
+          helpExists (findNum, vec, mid + 1, high)
+        else
+          helpExists (findNum, vec, low, mid - 1)
+      end
+    else
+      false
+
+  fun exists (findNum, vec) =
+    helpExists (findNum, vec, 0, Vector.length vec - 1)
+
   fun helpFind (findNum, vec, low, high) =
     if high >= low then
       let
@@ -16,8 +34,7 @@ struct
       end
     else
       ~1
-  in
+
   fun find (findNum, vec) =
     helpFind (findNum, vec, 0, Vector.length vec - 1)
-  end
 end

fcore/game-update.sml

@@ -47,13 +47,20 @@ struct
         end
     | [] => acc
 
-  fun checkEnemiesWhileAttacking (player, enemies, lst, acc) =
+  (* removes enemies from `enemies` vector when that enemy is in collisions *)
+  fun filterEnemyCollisions (pos, collisions, enemies: enemy vector, acc) =
+    if pos < 0 then
+      Vector.fromList acc
+    else
       let
-      open QuadTree
+        val enemy = Vector.sub (enemies, pos)
       in
-      case lst of
+        if BinSearch.exists (#id enemy, collisions) then
-        enemyID :: tl => (* placeholder *) acc
+          (* filter out *)
-      | [] => acc
+          filterEnemyCollisions (pos - 1, collisions, enemies, acc)
+        else
+          (* don't filter out *)
+          filterEnemyCollisions (pos - 1, collisions, enemies, enemy :: acc)
       end
 
   fun checkPlayerEnemyCollisions (player, game) =
@@ -108,6 +115,10 @@ struct
             val patches =
               checkEnemiesWhileAttacking (player, enemies, enemyCollisions, [])
             val player = Player.withPatches (player, patches)
+
+            val enemyCollisions = Vector.fromList enemyCollisions
+            val enemies = filterEnemyCollisions
+              (Vector.length enemies - 1, enemyCollisions, enemies, [])
           in
             (player, enemies)
           end
@@ -122,6 +133,9 @@ struct
 
       (* check player-enemy collisions and react *)
       val (player, enemies) = checkPlayerEnemyCollisions (player, game)
+
+      (* create enemy quad tree from list of new enemies *)
+      val enemyTree = Enemy.generateTree enemies
     in
       { player = player
       , walls = walls