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

---
 demo/sandbox.scm | 46 +++++++++++-----------------------------------
 1 file changed, 11 insertions(+), 35 deletions(-)

(limited to 'demo/sandbox.scm')

diff --git a/demo/sandbox.scm b/demo/sandbox.scm
index a34ebd9..09c31fb 100644
--- a/demo/sandbox.scm
+++ b/demo/sandbox.scm
@@ -2,7 +2,6 @@
         (chicken base)
         (chicken random)
         (only srfi-1 iota take)
-        (only srfi-197 chain)
         (prefix sdl2 "sdl2:")
         (prefix sdl2-ttf "ttf:")
         (prefix sdl2-image "img:")
@@ -73,39 +72,18 @@
         #:tile-id 1
         #:demo-id id #:demo-since-jump 0))
 
-;; ── Per-entity physics ──────────────────────────────────────────────────────
+;; ── Per-entity intent ───────────────────────────────────────────────────────
 
-(define (run-physics e tm)
-  (chain e
-         (apply-gravity _)
-         (apply-velocity-x _)
-         (resolve-tile-collisions-x _ tm)
-         (apply-velocity-y _)
-         (resolve-tile-collisions-y _ tm)))
-
-(define (update-demo-bot e dt tm)
+(define (update-demo-bot e dt)
   (let* ((id       (entity-ref e #:demo-id 0))
          (phase    (modulo (+ *demo-t* (* id 400.0)) +demo-bot-cycle-ms+))
          (vx       (if (< phase +demo-bot-half-cycle-ms+) 3.0 -3.0))
-         (e        (entity-set e #:vx vx))
          (ground?  (entity-ref e #:on-ground? #f))
          (since    (+ (entity-ref e #:demo-since-jump 0) dt))
          (jump?    (and ground? (>= since +demo-bot-jump-interval-ms+)))
-         (since    (if jump? 0 since)))
-    (chain (entity-set e #:demo-since-jump since)
-           (apply-jump _ jump?)
-           (apply-acceleration _)
-           (run-physics _ tm))))
-
-(define (integrate-entity e dt tm)
-  (case (entity-type e)
-    ((demo-bot) (update-demo-bot e dt tm))
-    ((box)      (run-physics e tm))
-    (else
-      (if (and (entity-ref e #:group-origin? #f)
-               (entity-ref e #:gravity? #f))
-          (run-physics e tm)
-          e))))
+         (since    (if jump? 0 since))
+         (ay       (if jump? (- *jump-force*) 0)))
+    (entity-set (entity-set (entity-set e #:vx vx) #:demo-since-jump since) #:ay ay)))
 
 ;; ── Scene builder ───────────────────────────────────────────────────────────
 
@@ -159,14 +137,12 @@
 
     update: (lambda (game dt)
       (set! *demo-t* (+ *demo-t* dt))
-      (let ((tm (scene-tilemap (game-scene game))))
+      (let ((scene (game-scene game)))
         (game-scene-set! game
-          (chain (game-scene game)
-            (scene-map-entities _ (cut step-tweens <> dt))
-            (scene-map-entities _ (cut integrate-entity <> dt tm))
-            (scene-transform-entities _ sync-groups)
-            (scene-transform-entities _ resolve-entity-collisions)
-            (scene-map-entities _
-              (lambda (e) (detect-on-solid e tm (scene-entities _))))))))))
+          (scene-map-entities scene
+            (lambda (e)
+              (if (eq? (entity-type e) 'demo-bot)
+                  (update-demo-bot e dt)
+                  e))))))))
 
 (game-run! *game*)
-- 
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