reimplement enemy-filter loop (now enemy's reaction, and decision to possibly filter, is fully under enemy's control - physics, damage reaction, whether to filter or update enemy's state, etc.)

fcore/enemy/enemy-patch.sml

@@ -0,0 +1,68 @@
+signature ENEMY_PATCH =
+sig
+  datatype enemy_patch =
+    W_HEALTH of int
+  | W_X of int
+  | W_Y of int
+  | W_X_AXIS of GameType.x_axis
+  | W_Y_AXIS of GameType.y_axis
+  | W_PLAT_ID of int
+  | W_NEXT_PLAT_ID of int
+
+  val withPatch: GameType.enemy * enemy_patch -> GameType.enemy
+
+  val withPatches: GameType.enemy * enemy_patch list -> GameType.enemy
+end
+
+structure EnemyPatch: ENEMY_PATCH =
+struct
+  datatype enemy_patch =
+    W_HEALTH of int
+  | W_X of int
+  | W_Y of int
+  | W_X_AXIS of GameType.x_axis
+  | W_Y_AXIS of GameType.y_axis
+  | W_PLAT_ID of int
+  | W_NEXT_PLAT_ID of int
+
+  fun mkEnemy (id, health, x, y, xAxis, yAxis, variant, platID, nextPlatID) =
+    { id = id
+    , health = health
+    , x = x
+    , y = y
+    , xAxis = xAxis
+    , yAxis = yAxis
+    , variant = variant
+    , platID = platID
+    , nextPlatID = nextPlatID
+    }
+
+  fun withPatch (enemy, patch) =
+    let
+      val {id, health, x, y, xAxis, yAxis, variant, platID, nextPlatID} = enemy
+    in
+      case patch of
+        W_HEALTH health =>
+          mkEnemy (id, health, x, y, xAxis, yAxis, variant, platID, nextPlatID)
+      | W_X x =>
+          mkEnemy (id, health, x, y, xAxis, yAxis, variant, platID, nextPlatID)
+      | W_X_AXIS xAxis =>
+          mkEnemy (id, health, x, y, xAxis, yAxis, variant, platID, nextPlatID)
+      | W_Y y =>
+          mkEnemy (id, health, x, y, xAxis, yAxis, variant, platID, nextPlatID)
+      | W_Y_AXIS yAxis =>
+          mkEnemy (id, health, x, y, xAxis, yAxis, variant, platID, nextPlatID)
+      | W_PLAT_ID platID =>
+          mkEnemy (id, health, x, y, xAxis, yAxis, variant, platID, nextPlatID)
+      | W_NEXT_PLAT_ID nextPlatID =>
+          mkEnemy (id, health, x, y, xAxis, yAxis, variant, platID, nextPlatID)
+    end
+
+  fun withPatches (enemy, lst) =
+    case lst of
+      hd :: tl =>
+        let val enemy = withPatch (enemy, hd)
+        in withPatches (enemy, tl)
+        end
+    | [] => enemy
+end