From afc30a12e25215ff5e9226c3b4f8fd127d9a4d68 Mon Sep 17 00:00:00 2001
From: Gene Pasquet <dev@etenil.net>
Date: Wed, 8 Apr 2026 07:08:54 +0100
Subject: Move the engine-update to the scene

---
 engine.scm | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

(limited to 'engine.scm')

diff --git a/engine.scm b/engine.scm
index e3a1fb0..95d33b9 100644
--- a/engine.scm
+++ b/engine.scm
@@ -10,6 +10,8 @@
         defstruct
         downstroke-world
         downstroke-input
+        downstroke-physics
+        downstroke-tween
         downstroke-assets
         downstroke-renderer)
 
@@ -39,6 +41,26 @@
 ;; ── Public constructor wrapper ─────────────────────────────────────────────
 ;; Wraps the auto-generated make-game (renamed to make-game*) with default values
 
+;; ── Default engine update ────────────────────────────────────────────────
+;; Standard physics pipeline: tweens → acceleration → gravity → velocity →
+;; tile collisions → ground detection → entity collisions → group sync.
+;; Runs automatically each frame unless overridden or disabled.
+
+(define (default-engine-update game dt)
+  (let ((scene (game-scene game)))
+    (when scene
+      (let* ((scene (scene-map-entities scene (cut step-tweens <> scene dt)))
+             (scene (scene-map-entities scene (cut apply-acceleration <> scene dt)))
+             (scene (scene-map-entities scene (cut apply-gravity <> scene dt)))
+             (scene (scene-map-entities scene (cut apply-velocity-x <> scene dt)))
+             (scene (scene-map-entities scene (cut resolve-tile-collisions-x <> scene dt)))
+             (scene (scene-map-entities scene (cut apply-velocity-y <> scene dt)))
+             (scene (scene-map-entities scene (cut resolve-tile-collisions-y <> scene dt)))
+             (scene (scene-map-entities scene (cut detect-on-solid <> scene dt)))
+             (scene (scene-transform-entities scene resolve-entity-collisions))
+             (scene (scene-transform-entities scene sync-groups)))
+        (game-scene-set! game scene)))))
+
 (define (make-game #!key
     (title "Downstroke Game")
     (width 640) (height 480)
@@ -192,6 +214,12 @@
                                       (game-input-config game))))
       (game-input-set! game input)
       (unless (input-held? input 'quit)
+        (let ((scene (game-scene game)))
+          (when scene
+            (let ((eu (scene-engine-update scene)))
+              (cond
+                ((procedure? eu) (eu game dt))
+                ((not eu) (default-engine-update game dt))))))
         (receive (update-fn render-fn) (resolve-hooks game)
           (when update-fn (update-fn game dt))
           (when (game-scene game)
-- 
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