From 95d31ad231800026e7b0a44ddda42c584dad5671 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson@member.fsf.org>
Date: Mon, 26 Aug 2013 22:09:45 -0400
Subject: Make the origin the top-left corner of the window again.

---
 2d/font.scm | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

(limited to '2d/font.scm')

diff --git a/2d/font.scm b/2d/font.scm
index 70b0904..8bf66a3 100644
--- a/2d/font.scm
+++ b/2d/font.scm
@@ -47,11 +47,21 @@
     (ftgl-set-font-face-size ftgl-font size 72)
     (make-font ftgl-font size)))
 
+(define (flip-text font)
+  "Flips current GL matrix about the x-axis and translates by the
+negative font ascender value. This is necessary before rendering text
+because guile-2d flips the y-axis so that the origin is in the
+upper-left corner rather than the bottom-left."
+  (gl-scale 1 -1 1)
+  (gl-translate 0 (- (ftgl-get-font-ascender (font-ftgl-font font))) 0))
+
 (define (draw-font font text)
   "Renders the string text using the given font."
-  (ftgl-render-font (font-ftgl-font font)
-                    text
-                    (ftgl-render-mode all)))
+  (with-gl-push-matrix
+    (flip-text font)
+    (ftgl-render-font (font-ftgl-font font)
+                      text
+                      (ftgl-render-mode all))))
 
 (export <font>
         make-font
@@ -88,6 +98,7 @@
   (let ((pos (textbox-position textbox)))
     (with-gl-push-matrix
       (gl-translate (vx pos) (vy pos) 0)
+      (flip-text (textbox-font textbox))
       (apply-color (textbox-color textbox))
       (ftgl-render-layout (textbox-layout textbox)
                           (textbox-text textbox)
-- 
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