Author: Danny Milosavljevic <dannym@friendly-machines.com>
Date: 2024-12-17 21:00:00 CET
Subject: Make bitmap fonts work even in glut
License: Same as Perl.

--- orig/PDL-2.019/Graphics/TriD/POGL/OpenGL.pm	2018-05-05 19:56:29.000000000 +0200
+++ PDL-2.019/Graphics/TriD/POGL/OpenGL.pm	2024-12-17 22:56:30.043984134 +0100
@@ -358,9 +358,34 @@
 
 =cut
 
+use OpenGL qw(GL_COMPILE GLUT_BITMAP_9_BY_15 GLUT_BITMAP_8_BY_13);
+use constant GLUT_FONTS => {
+    '9x15' => GLUT_BITMAP_9_BY_15,
+    '8x13' => GLUT_BITMAP_8_BY_13,
+};
+
 sub glpRasterFont{
    my($this,@args) = @_;
-   OpenGL::glpRasterFont($args[0],$args[1],$args[2],$this->{Display});
+   # see also OpenGL::glpPrintString($::lb,$header);
+   if ( $this->{window_type} eq 'glut' ) {
+       my $font_name = $args[0] || '8x13';
+       my $font = GLUT_FONTS->{$font_name} || GLUT_FONTS->{'8x13'};
+       my $start_char = $args[1] || 0;
+       my $num_chars = $args[2] || 128;
+       my $cache_key = "${font_name};${start_char};${num_chars}";
+       unless (exists $this->{font_cache}{$cache_key}) {
+           my $base = OpenGL::glGenLists($num_chars);
+           for my $i (0..($num_chars - 1)) {
+               OpenGL::glNewList($base + $i, GL_COMPILE);
+               OpenGL::glutBitmapCharacter($font, $start_char + $i);
+               OpenGL::glEndList();
+           }
+           $this->{font_cache}{$cache_key} = $base;
+       }
+       return $this->{font_cache}{$cache_key};
+   } else {
+       return OpenGL::glpRasterFont($args[0],$args[1],$args[2],$this->{Display});
+   }
 }