From 6b2012b223774c09fa60ab87273d60e07ac0c608 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Mon, 16 Nov 2020 17:24:45 -0500
Subject: graphics: tiled: Ensure that point->tile always returns integers.

---
 chickadee/graphics/tiled.scm | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/chickadee/graphics/tiled.scm b/chickadee/graphics/tiled.scm
index 8da86b5..46dfea3 100644
--- a/chickadee/graphics/tiled.scm
+++ b/chickadee/graphics/tiled.scm
@@ -197,8 +197,8 @@
 
 (define (point->tile tile-map x y)
   "Translate the pixel coordinates (X, Y) into tile coordinates."
-  (values (floor (/ x (tile-map-tile-width tile-map)))
-          (floor (/ y (tile-map-tile-height tile-map)))))
+  (values (inexact->exact (floor (/ x (tile-map-tile-width tile-map))))
+          (inexact->exact (floor (/ y (tile-map-tile-height tile-map))))))
 
 (define (load-tile-map file-name)
   "Load the Tiled TMX formatted map in FILE-NAME."
@@ -464,31 +464,36 @@
 
 (define %null-vec2 (vec2 0.0 0.0))
 (define %default-scale (vec2 1.0 1.0))
-(define %matrix (make-null-matrix4))
-(define %region (make-rect 0.0 0.0 0.0 0.0))
+(define *matrix* (make-null-matrix4))
+(define *position* (vec2 0.0 0.0))
+(define *region* (make-rect 0.0 0.0 0.0 0.0))
 
 ;; Make a default region that is as big as the viewport.
 (define (default-region tile-map position)
   (let ((vp (current-viewport)))
-    (set-rect-x! %region (- (vec2-x position)))
-    (set-rect-y! %region (- (vec2-y position)))
-    (set-rect-width! %region (viewport-width vp))
-    (set-rect-height! %region (viewport-height vp))
-    %region))
+    (set-rect-x! *region* (vec2-x position))
+    (set-rect-y! *region* (vec2-y position))
+    (set-rect-width! *region* (viewport-width vp))
+    (set-rect-height! *region* (viewport-height vp))
+    *region*))
 
 (define* (draw-tile-map tile-map
                         #:key
                         layers
+                        (camera %null-vec2)
                         (position %null-vec2)
-                        (region (default-region tile-map position))
+                        (region (default-region tile-map camera))
                         (origin %null-vec2)
                         (scale %default-scale)
                         (rotation 0.0))
   "Draw TILE-MAP.  By default, all layers are drawn.  The LAYERS
 argument may be used to specify a list of layers to draw, instead."
-  (matrix4-2d-transform! %matrix
+  (vec2-copy! camera *position*)
+  (vec2-mult! *position* -1.0)
+  (vec2-add! *position* position)
+  (matrix4-2d-transform! *matrix*
                          #:origin origin
-                         #:position position
+                         #:position *position*
                          #:rotation rotation
                          #:scale scale)
-  (draw-tile-map* tile-map %matrix region #:layers layers))
+  (draw-tile-map* tile-map *matrix* region #:layers layers))
-- 
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