add code to make enemy fall when attacked by projectile (assuming health is enough)

fcore/player/player-attack.sml

@@ -8,33 +8,24 @@ struct
 
          open EnemyType
 
-         fun onAttacked (enemyID, enemy, enemyMap, defeatedList) =
+         fun defeatEnemy (enemyID, enemyMap, defeatedList) =
+           let
+             val defeatedList = {angle = 1} :: defeatedList
+             val enemyMap = EnemyMap.remove (enemyID, enemyMap)
+           in
+             (defeatedList, enemyMap)
+           end
+
+         fun onPlayerAttack (enemyID, enemy, enemyMap, defeatedList) =
            case #variant enemy of
-             PATROL_SLIME =>
-               let
-                 val defeatedList = {angle = 1} :: defeatedList
-                 val enemyMap = EnemyMap.remove (enemyID, enemyMap)
-               in
-                 (defeatedList, enemyMap)
-               end
-           | FOLLOW_SLIME =>
-               let
-                 val defeatedList = {angle = 1} :: defeatedList
-                 val enemyMap = EnemyMap.remove (enemyID, enemyMap)
-               in
-                 (defeatedList, enemyMap)
-               end
-           | STRAIGHT_BAT =>
-               let
-                 val defeatedList = {angle = 1} :: defeatedList
-                 val enemyMap = EnemyMap.remove (enemyID, enemyMap)
-               in
-                 (defeatedList, enemyMap)
-               end
+             PATROL_SLIME => defeatEnemy (enemyID, enemyMap, defeatedList)
+           | FOLLOW_SLIME => defeatEnemy (enemyID, enemyMap, defeatedList)
+           | STRAIGHT_BAT => defeatEnemy (enemyID, enemyMap, defeatedList)
 
          fun fold (enemyID, (), (defeatedList, enemyMap)) =
            case EnemyMap.get (enemyID, enemyMap) of
-             SOME enemy => onAttacked (enemyID, enemy, enemyMap, defeatedList)
+             SOME enemy =>
+               onPlayerAttack (enemyID, enemy, enemyMap, defeatedList)
            | NONE => (defeatedList, enemyMap)
        end)
 
@@ -66,4 +57,60 @@ struct
           end
       | _ => (player, enemyMap)
     end
+
+  structure ProjectileHitEnemy =
+    MakeQuadTreeFold
+      (struct
+         type env = unit
+         type state = EnemyType.falling_enemy list * EnemyMap.t
+
+         open EnemyType
+
+         fun onDefeated (enemyID, enemy, enemyMap, fallingList) =
+           let
+             val {x, y, variant, ...} = enemy
+             val fallingList = {x = x, y = y, variant = variant} :: fallingList
+             val enemyMap = EnemyMap.remove (enemyID, enemyMap)
+           in
+             (fallingList, enemyMap)
+           end
+
+         fun onProjectileAttack (enemyID, enemy, enemyMap, fallingList) =
+           case #variant enemy of
+             PATROL_SLIME => onDefeated (enemyID, enemy, enemyMap, fallingList)
+           | FOLLOW_SLIME => onDefeated (enemyID, enemy, enemyMap, fallingList)
+           | STRAIGHT_BAT => onDefeated (enemyID, enemy, enemyMap, fallingList)
+
+         fun fold (enemyID, (), (fallingList, enemyMap)) =
+           case EnemyMap.get (enemyID, enemyMap) of
+             SOME enemy =>
+               onProjectileAttack (enemyID, enemy, enemyMap, fallingList)
+           | NONE => (fallingList, enemyMap)
+       end)
+
+  fun helpProjectileHitEnemy (pos, projectiles, enemyTree, enemyMap, newFalling) =
+    if pos = Vector.length projectiles then
+      (newFalling, enemyMap)
+    else
+      let
+        val {x, y, ...}: PlayerType.player_projectile =
+          Vector.sub (projectiles, pos)
+        val size = Constants.projectileSizeInt
+        val (newFalling, enemyMap) = ProjectileHitEnemy.foldRegion
+          (x, y, size, size, (), (newFalling, enemyMap), enemyTree)
+      in
+        helpProjectileHitEnemy
+          (pos + 1, projectiles, enemyTree, enemyMap, newFalling)
+      end
+
+  fun projectileHitEnemy (projectiles, enemyMap, enemyTree, oldFalling) =
+    let
+      val (newFalling, enemyMap) = helpProjectileHitEnemy
+        (0, projectiles, enemyTree, enemyMap, [])
+
+      val newFalling = Vector.fromList newFalling
+      val allFalling = Vector.concat [newFalling, oldFalling]
+    in
+      (allFalling, enemyMap)
+    end
 end