From 528154a4645fdb82f623655ded4319d72877444b Mon Sep 17 00:00:00 2001
From: "Juan J. Martinez" <jjm@usebox.net>
Date: Tue, 16 May 2023 22:52:34 +0100
Subject: Change stage using a simple transition

---
 src/Game.hs          | 34 ++++++++++++++++++++++++----------
 src/Game/Entities.hs |  2 +-
 src/Game/State.hs    |  2 +-
 3 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/src/Game.hs b/src/Game.hs
index 7ed7ade..3338a8c 100644
--- a/src/Game.hs
+++ b/src/Game.hs
@@ -13,6 +13,7 @@ import qualified Game.Map as M
 import qualified Game.Sprites as S
 import qualified Game.State as GS
 import qualified Game.Toaster as T
+import qualified Game.Utils as U
 import SDL (($=))
 import qualified SDL
 import qualified SDL.Image
@@ -153,10 +154,10 @@ gameLoop e = do
             )
 
     SDL.rendererRenderTarget renderer $= Just canvas
-    SDL.clear renderer
 
     updatedEnv <- case state.playState of
       GS.GameOver -> gameOverLoop updatedToasterEnv
+      GS.ExitDone frames -> nextStageLoop updatedToasterEnv frames
       _ -> playLoop updatedToasterEnv
     T.render renderer updatedEnv.toaster
 
@@ -182,6 +183,8 @@ playLoop e = do
   -- to update the map viewport
   let (px, py) = E.playerPosition updated
 
+  SDL.clear renderer
+
   -- set the SDL viewport
   viewport <- M.viewport renderer map' px py (fromIntegral gameWidth) (fromIntegral gameHeight - H.height) (Just (0, H.height))
   -- render map and entities
@@ -206,20 +209,30 @@ playLoop e = do
       | state.batteries == state.totalBatteries && not state.exit = do
           es <- E.addExit env.entities x (y - 8) -- adjusted to player's height
           pure env {entities = es, state = state {GS.exit = True}}
-      | state.playState == GS.ExitDone = do
-          map' <- M.load (env.mapList !! (env.state.currentLevel + 1)) env.tsTexture
-          entities <- E.mkEntities env.sprites map' env.controlsRef
-          pure $
-            env
-              { map = map',
-                state = (GS.levelState env.state map') {GS.currentLevel = env.state.currentLevel + 1},
-                entities = entities
-              }
       | otherwise = pure env
       where
         state = env.state
         (x, y) = state.lastBattery
 
+nextStageLoop :: Env -> Int -> IO Env
+nextStageLoop e frames
+  -- erase the screen
+  | frames < fromIntegral gameWidth = do
+      SDL.fillRect e.renderer $ Just (U.rect 0 H.height (frames + 8) (fromIntegral gameHeight - H.height))
+      pure e {state = e.state {GS.playState = GS.ExitDone $ frames + 8}}
+  -- some delay after the transition is done
+  | frames < fromIntegral gameWidth + 32 =
+      pure e {state = e.state {GS.playState = GS.ExitDone $ frames + 1}}
+  | otherwise = do
+      map' <- M.load (e.mapList !! (e.state.currentLevel + 1)) e.tsTexture
+      entities <- E.mkEntities e.sprites map' e.controlsRef
+      pure $
+        e
+          { map = map',
+            state = (GS.levelState e.state map') {GS.currentLevel = e.state.currentLevel + 1},
+            entities = entities
+          }
+
 gameOverLoop :: Env -> IO Env
 gameOverLoop e = do
   let renderer = e.renderer
@@ -239,6 +252,7 @@ gameOverLoop e = do
       pure
         e {state = (GS.levelState e.state map') {GS.lives = GS.maxLives}, entities = entities}
     else do
+      SDL.clear renderer
       H.render renderer hud state
       title <- S.get sprites "game-over"
       S.render renderer title 112 80 0 0
diff --git a/src/Game/Entities.hs b/src/Game/Entities.hs
index 6ddf589..578bf51 100644
--- a/src/Game/Entities.hs
+++ b/src/Game/Entities.hs
@@ -116,7 +116,7 @@ updateAll es state = do
             ((head ents) {typ = TypeEffect} : tail ents)
             t
         ActionEntryDone -> processActions s {GS.playState = GS.InPlay} ents t
-        ActionExitDone -> processActions s {GS.playState = GS.ExitDone} ents t
+        ActionExitDone -> processActions s {GS.playState = GS.ExitDone 0} ents t
         ActionAddBlast x y d playerCollision isBlocked -> do
           blast <- mkBlast es.sprites x y d playerCollision isBlocked
           processActions s (ents ++ [blast]) t
diff --git a/src/Game/State.hs b/src/Game/State.hs
index df2d4fa..5c9de0b 100644
--- a/src/Game/State.hs
+++ b/src/Game/State.hs
@@ -6,7 +6,7 @@ import qualified Game.Map as M
 maxLives :: Int
 maxLives = 4
 
-data PlayState = InPlay | IntoStage | ExitStarted | ExitDone | GameOver deriving (Eq)
+data PlayState = InPlay | IntoStage | ExitStarted | ExitDone Int | GameOver deriving (Eq)
 
 data State = State
   { batteries :: Int,
-- 
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