From eceae08c4f6985c3cc30191ab33b22302578b81e Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Mon, 20 Aug 2018 20:22:44 -0400
Subject: math: vector: Add read syntax.

* chickadee/math/vector.scm (read-vec): New procedure.  Extend reader.
* examples/lines.scm: Use new vector read syntax.
* examples/nine-patch.scm: Ditto.
* examples/sprite.scm: Ditto.
* examples/text.scm: Ditto.
* examples/tiled.scm: Ditto.
---
 chickadee/math/vector.scm | 26 ++++++++++++++++++++++++++
 examples/lines.scm        |  4 ++--
 examples/nine-patch.scm   |  2 +-
 examples/sprite.scm       |  2 +-
 examples/text.scm         |  6 +++---
 examples/tiled.scm        |  2 +-
 6 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/chickadee/math/vector.scm b/chickadee/math/vector.scm
index 78aa564..2ae9187 100644
--- a/chickadee/math/vector.scm
+++ b/chickadee/math/vector.scm
@@ -311,3 +311,29 @@ polar coordinate (R, THETA)."
         (set-vec3-x! v (- (vec3-x v) (vec3-x x)))
         (set-vec3-y! v (- (vec3-y v) (vec3-y x)))
         (set-vec3-z! v (- (vec3-z v) (vec3-z x))))))
+
+;; Reader macro for vectors.
+(define (read-vec chr port)
+  (define (consume-whitespace port)
+    (when (char-whitespace? (peek-char port))
+      (read-char port)
+      (consume-whitespace port)))
+  (if (eq? (peek-char port) #\()
+      (read-char port)
+      (error "expected opening #\\("))
+  (consume-whitespace port)
+  (let ((x (read port))
+        (y (read port)))
+    (if (eq? (peek-char port) #\))
+        (begin
+          (read-char port)
+          `(vec2 ,x ,y))
+        (let ((z (read port)))
+          (consume-whitespace port)
+          (if (eq? (peek-char port) #\))
+              (begin
+                (read-char port)
+                `(vec3 ,x ,y ,z))
+              (error "expected terminating #\\)"))))))
+
+(read-hash-extend #\v read-vec)
diff --git a/examples/lines.scm b/examples/lines.scm
index 5e800e0..75aadf1 100644
--- a/examples/lines.scm
+++ b/examples/lines.scm
@@ -8,8 +8,8 @@
 (define lines
   (list-tabulate 48
                  (lambda (n)
-                   (list (vec2 (random 640) (random 480))
-                         (vec2 (random 640) (random 480))
+                   (list #v((random 640) (random 480))
+                         #v((random 640) (random 480))
                          (make-color (random:uniform)
                                      (random:uniform)
                                      (random:uniform)
diff --git a/examples/nine-patch.scm b/examples/nine-patch.scm
index ed03cab..2852245 100644
--- a/examples/nine-patch.scm
+++ b/examples/nine-patch.scm
@@ -14,6 +14,6 @@
 
 (define (draw alpha)
   (draw-nine-patch image (make-rect 192.0 192.0 256.0 96.0) #:margin 6)
-  (draw-text font "I am error." (vec2 200.0 266.0)))
+  (draw-text font "I am error." #v(200.0 266.0)))
 
 (run-game/sdl #:load load #:draw draw)
diff --git a/examples/sprite.scm b/examples/sprite.scm
index 12a9ffb..8e54f21 100644
--- a/examples/sprite.scm
+++ b/examples/sprite.scm
@@ -9,6 +9,6 @@
   (set! sprite (load-image "images/chickadee.png")))
 
 (define (draw alpha)
-  (draw-sprite sprite (vec2 256.0 176.0)))
+  (draw-sprite sprite #v(256.0 176.0)))
 
 (run-game/sdl #:load load #:draw draw)
diff --git a/examples/text.scm b/examples/text.scm
index fd299b7..74c2301 100644
--- a/examples/text.scm
+++ b/examples/text.scm
@@ -9,11 +9,11 @@
 
 (define (draw alpha)
   (draw-text font "(draw-text font \"Hello, world!\" (vec2 100.0 200.0))"
-             (vec2 100.0 200.0))
+             #v(100.0 200.0))
   (draw-text font "Chickadee is a game development toolkit for Guile Scheme."
-             (vec2 100.0 150.0))
+             #v(100.0 150.0))
   (draw-text font "The quick brown fox jumps over the lazy dog"
-             (vec2 100.0 100.0)))
+             #v(100.0 100.0)))
 
 (define (key-press key scan modifiers repeat?)
   (when (eq? key 'q)
diff --git a/examples/tiled.scm b/examples/tiled.scm
index 3d33052..b5fb8b6 100644
--- a/examples/tiled.scm
+++ b/examples/tiled.scm
@@ -5,7 +5,7 @@
              (ice-9 match))
 
 (define map #f)
-(define camera (vec2 0.0 0.0))
+(define camera #v(0.0 0.0))
 
 (define (load)
   (set! map (load-tile-map "maps/example.tmx")))
-- 
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