From ee937abcfeb7bd65617790936bb6ee25a2b1760a Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Mon, 23 Oct 2023 22:32:20 -0400
Subject: Use tagged vector for level.

---
 game.scm | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/game.scm b/game.scm
index 74c4da8..a4c646c 100644
--- a/game.scm
+++ b/game.scm
@@ -446,6 +446,11 @@
   (define tile-width 16.0)
   (define tile-height 16.0)
   (define level-width 15)
+  (define-type level
+    %make-level
+    level?
+    (height level-height set-level-height!)
+    (tiles level-tiles set-level-tiles!))
   (define (make-level tiles)
     (let ((k (length tiles)))
       (unless (= (modulo k level-width) 0)
@@ -478,10 +483,7 @@
                        (x-loop rest (+ x 1))))
                     tiles))
               (+ y 1)))))
-        (vector (/ k level-width) bv))))
-  (define (level-height level)
-    (match level
-      (#(height tiles) height)))
+        (%make-level (/ k level-width) bv))))
   (define-syntax-rule (define-level name tile ...)
     (define name (make-level '(tile ...))))
   (define-level level
@@ -542,7 +544,7 @@
     (* (+ (* level-width y) x) %tile-size))
   (define (point-collides-with-level? level x y)
     (match level
-      (#(height tiles)
+      (#('level height tiles)
        (let ((tx (trunc (/ x tile-width)))
              (ty (trunc (/ y tile-height))))
          (and (>= tx 0) (< tx level-width)
@@ -550,7 +552,7 @@
               (>= (f64-ref tiles (level-offset tx ty)) 0))))))
   (define (rect-collides-with-level? level x y w h)
     (match level
-      (#(height tiles)
+      (#('level height tiles)
        (let* ((y (+ y (- (* height tile-height) game-height *scroll*)))
               (tx0 (trunc (/ x tile-width)))
               (ty0 (trunc (/ y tile-height)))
@@ -566,7 +568,7 @@
              (occupied? tx0 ty1))))))
   (define (draw-tiles level)
     (match level
-      (#(height tiles)
+      (#('level height tiles)
        (let* ((tw tile-width)
               (th tile-height)
               (pixel-y-offset (- (* height th) *scroll* game-height))
@@ -584,10 +586,10 @@
                (draw-image context image:map
                            (* t tw) 0.0 tw th
                            tx (- ty pixel-y-offset) tw th))))))))
-  (define max-scroll (- (* (vector-ref level 0) tile-height) game-height))
+  (define max-scroll (- (* (level-height level) tile-height) game-height))
   (define (level-update! level)
     (match level
-      (#(height tiles)
+      (#('level height tiles)
        (let ((scroll (min (+ *scroll* *scroll-speed*) max-scroll)))
          (set! *scroll* scroll)
          (let ((row (max (- (trunc
-- 
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