From 7a5517571dee225462586fadad2165d990d68221 Mon Sep 17 00:00:00 2001
From: Humza Shahid <humzasaur@gmail.com>
Date: Fri, 24 Jan 2025 22:51:20 +0000
Subject: [PATCH] add functionality for enemy to walk to appropriate position
 if next platform is below current one, but only partially overlapping with
 current platform so enemy will not reach it if they drop down from current
 position

---
 fcore/enemy-behaviour.sml | 81 ++++++++++++++++++++++++++++-----------
 1 file changed, 58 insertions(+), 23 deletions(-)

diff --git a/fcore/enemy-behaviour.sml b/fcore/enemy-behaviour.sml
index 2a37280..8b64718 100644
--- a/fcore/enemy-behaviour.sml
+++ b/fcore/enemy-behaviour.sml
@@ -88,10 +88,10 @@ struct
             if
               hasWallAhead
             then EnemyPatch.W_X_AXIS MOVE_RIGHT :: acc
-            else (* invert direction if moving further left 
-                  * will result in falling down  *) if
-              canWalkAhead (searchStartX, y, wallTree, platformTree)
-            then acc
+            else if canWalkAhead (searchStartX, y, wallTree, platformTree) then 
+              (* invert direction if moving further left 
+               * will result in falling down  *) 
+              acc
             else EnemyPatch.W_X_AXIS MOVE_RIGHT :: acc
           end
       | MOVE_RIGHT =>
@@ -122,10 +122,10 @@ struct
             if
               hasWallAhead
             then EnemyPatch.W_X_AXIS MOVE_LEFT :: acc
-            else (* invert direction if moving further right
-                  * will result in falling down  *) if
-              canWalkAhead (searchStartX, y, wallTree, platformTree)
-            then acc
+            else if canWalkAhead (searchStartX, y, wallTree, platformTree) then 
+              (* invert direction if moving further right
+               * will result in falling down  *) 
+              acc
             else EnemyPatch.W_X_AXIS MOVE_LEFT :: acc
           end
       | STAY_STILL => acc
@@ -190,7 +190,7 @@ struct
       val nPlatFinishX = nPlatX + nPlatW
     in
       (isBetween (nPlatX, pPlatX, nPlatFinishX)
-      orelse isBetween (nPlatX, pPlatFinishX, nPlatFinishX))
+       orelse isBetween (nPlatX, pPlatFinishX, nPlatFinishX))
       andalso pPlatY > nPlatY
     end
 
@@ -206,33 +206,65 @@ struct
       val standingOnPlat = standingOnArea (enemy, platformTree)
     in
       if ey >= platY andalso standingOnPlat then
-        if isBetween (platX, ecx, platFinishX) then
+        if
+          isBetween (platX, ecx, platFinishX)
+        then
           (* can jump from same position enemy is at *)
           case eyAxis of
             ON_GROUND => EnemyPatch.W_Y_AXIS (JUMPING 0) :: acc
           | FALLING => EnemyPatch.W_Y_AXIS (JUMPING 0) :: acc
           | _ => acc
-        else
+        else 
           (* have to travel either left or right before jumping *) 
           if ecx < platX then
             EnemyPatch.W_X_AXIS MOVE_RIGHT :: acc
           else
             EnemyPatch.W_X_AXIS MOVE_LEFT :: acc
-        else 
-          acc
+      else
+        acc
     end
 
-  fun canDrop (nextPlatform, platformTree, enemy) =
+  fun canDrop (prevPlatform, nextPlatform) =
     let
-      val {x = platX, y = platY, width = platW, ...} = nextPlatform
-      val platFinishX = platX + platW
+      val {x = pPlatX, y = pPlatY, width = pPlatW, ...} = prevPlatform
+      val pPlatFinishX = pPlatX + pPlatW
 
-      val {x = eX, y = ey, yAxis = eyAxis, ...} = enemy
+      val {x = nPlatX, y = nPlatY, width = nPlatW, ...} = nextPlatform
+      val nPlatFinishX = nPlatX + nPlatW
+    in
+      (isBetween (nPlatX, pPlatX, nPlatFinishX)
+       orelse isBetween (nPlatX, pPlatFinishX, nPlatFinishX))
+      andalso pPlatY < nPlatY
+    end
+
+  fun getDropPatches (nextPlatform, platformTree, enemy, acc) =
+    let
+      val {x = platX, y = platY, width = platWidth, ...} = nextPlatform
+      val platFinishX = platX + platWidth
+
+      val {x = eX, y = ey, yAxis = eyAxis, xAxis = exAxis, ...} = enemy
+      val ecx = eX + (Constants.enemySize div 2)
+      val ey = ey + Constants.enemySize
 
       val standingOnPlat = standingOnArea (enemy, platformTree)
     in
-      isBetween (platX, eX, platFinishX) andalso standingOnPlat
-      andalso ey < platY
+      if ey <= platY andalso standingOnPlat then
+        if
+          isBetween (platX, ecx, platFinishX)
+        then
+          (* can jump from same position enemy is at *)
+          case eyAxis of
+            ON_GROUND => EnemyPatch.W_Y_AXIS DROP_BELOW_PLATFORM :: acc
+          | FALLING => EnemyPatch.W_Y_AXIS DROP_BELOW_PLATFORM :: acc
+          | _ => acc
+        else 
+          (* have to travel either left or right before jumping *) 
+          if ecx < platX then
+            EnemyPatch.W_X_AXIS MOVE_RIGHT :: acc
+          else
+            EnemyPatch.W_X_AXIS MOVE_LEFT :: acc
+      else
+        acc
     end
 
   (* get patches to help enemy move to nextPlatformID *)
@@ -245,11 +277,14 @@ struct
       val {x = eX, y = ey, yAxis = eyAxis, ...} = enemy
 
       val canJump = canJump (currentPlatform, nextPlatform)
-      val canDrop = canDrop (nextPlatform, platformTree, enemy)
+      val canDrop = canDrop (currentPlatform, nextPlatform)
     in
-      if canJump then getJumpPatches (nextPlatform, platformTree, enemy, acc)
-      else if canDrop then EnemyPatch.W_Y_AXIS DROP_BELOW_PLATFORM :: acc
-      else acc
+      if canJump then
+        getJumpPatches (nextPlatform, platformTree, enemy, acc)
+      else if canDrop then
+        getDropPatches (nextPlatform, platformTree, enemy, acc)
+      else
+        acc
     end
 
   fun canJumpOnPlatform (player, platforms, enemy: enemy, platformTree, acc) =