Initial port of macroknight to an engine

1 files changed, 59 insertions, 0 deletions

diff --git a/world.scm b/world.scm
new file mode 100644
index 0000000..ee1d60c
--- /dev/null
+++ b/world.scm
@@ -0,0 +1,59 @@
+(module world
+    *
+  (import scheme
+	  (chicken base)
+	  (only srfi-1 fold filter)
+	  defstruct
+	  tilemap
+	  entity)
+  ;; Scene = current level: tilemap (layers, objects) + list of entities.
+
+  ;; Returns tile-id if the cell at (col, row) in this layer is non-zero, #f otherwise.
+  (define (layer-tile-at layer col row)
+    (let ((rows (layer-map layer)))
+      (and (< row (length rows))
+           (let ((row-data (list-ref rows row)))
+             (and (< col (length row-data))
+                  (let ((tile-id (list-ref row-data col)))
+                    (and (not (zero? tile-id)) tile-id)))))))
+
+  (define (tilemap-tile-at tilemap col row)
+    "Get the tile ID at grid position (col, row).
+     Returns 0 if out of bounds or if all layers have 0 at that cell."
+    (let ((width  (tilemap-width  tilemap))
+          (height (tilemap-height tilemap)))
+      (if (or (< col 0) (>= col width) (< row 0) (>= row height))
+          0
+          (let loop ((layers (tilemap-layers tilemap)))
+            (if (null? layers)
+                0
+                (or (layer-tile-at (car layers) col row)
+                    (loop (cdr layers))))))))
+
+  (defstruct camera x y)
+
+  (defstruct scene
+    entities
+    tilemap
+    camera
+    tileset-texture)
+
+  (define (scene-add-entity scene entity)
+    (scene-entities-set! scene (append (scene-entities scene) (list entity)))
+    scene)
+
+  (define (scene-update-entities scene . procs)
+    "Apply each proc in sequence to the scene's entities; each proc maps over all entities.
+     The scene's entity list is replaced once with the final result."
+    (scene-entities-set! scene
+      (fold (lambda (proc es) (map proc es))
+            (scene-entities scene)
+            procs))
+    scene)
+
+  (define (scene-filter-entities scene pred)
+    "Remove all entities from scene that do not satisfy pred."
+    (scene-entities-set! scene
+      (filter pred (scene-entities scene)))
+    scene)
+)