From 27a6fd9609c08b60057b0482a835dc27a64a0786 Mon Sep 17 00:00:00 2001
From: ManoloFLTK <41016272+ManoloFLTK@users.noreply.github.com>
Date: Wed, 23 Nov 2022 17:24:20 +0100
Subject: [PATCH] Configure-based build: control presence of GL-related
 packages

---
 configure.ac                                        | 8 +++++---
 src/drivers/Wayland/fl_wayland_gl_platform_init.cxx | 4 ++++
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/configure.ac b/configure.ac
index d56b2b64f..5e962cccf 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1044,9 +1044,11 @@ AS_CASE([$host_os_gui], [cygwin* | mingw*], [
 
       AS_IF([test x$enable_gl != xno], [
           AS_IF([$PKGCONFIG --exists gl], [
-             AC_DEFINE([HAVE_GL])
-             GLLIBS="$($PKGCONFIG --libs wayland-egl) $($PKGCONFIG --libs egl) $($PKGCONFIG --libs gl) $GLLIBS"
-          ])
+            AS_IF([$PKGCONFIG --exists egl], [
+              AS_IF([$PKGCONFIG --exists wayland-egl], [
+                AC_DEFINE([HAVE_GL])
+                GLLIBS="$($PKGCONFIG --libs wayland-egl) $($PKGCONFIG --libs egl) $($PKGCONFIG --libs gl) $GLLIBS"
+          ])])])
           AS_IF([$PKGCONFIG --exists glu], [
              AC_DEFINE([HAVE_GL_GLU_H])
              GLLIBS="$($PKGCONFIG --libs glu) $GLLIBS"
diff --git a/src/drivers/Wayland/fl_wayland_gl_platform_init.cxx b/src/drivers/Wayland/fl_wayland_gl_platform_init.cxx
index 293641d05..1c734be47 100644
--- a/src/drivers/Wayland/fl_wayland_gl_platform_init.cxx
+++ b/src/drivers/Wayland/fl_wayland_gl_platform_init.cxx
@@ -14,6 +14,8 @@
 //     https://www.fltk.org/bugs.php
 //
 
+#include <config.h>
+#if HAVE_GL
 
 #include "Fl_Wayland_Gl_Window_Driver.H"
 #include "Fl_Wayland_Screen_Driver.H"
@@ -30,3 +32,5 @@ Fl_Gl_Window_Driver *Fl_Gl_Window_Driver::newGlWindowDriver(Fl_Gl_Window *w)
   return new Fl_Wayland_Gl_Window_Driver(w);
 #endif
 }
+
+#endif // HAVE_GL