From cc195a147078190bd6116165bab35af05d0ee1dc Mon Sep 17 00:00:00 2001
From: Kevin Bowling <kevin.bowling@kev009.com>
Date: Wed, 23 Jun 2021 00:01:26 -0700
Subject: build: Add support for libglvnd

---
 Makefile.am  |  6 +++---
 configure.ac | 54 ++++++++++++++++++++++++++++++++++++------------------
 2 files changed, 39 insertions(+), 21 deletions(-)

diff --git a/Makefile.am b/Makefile.am
index 3050df1..2186347 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -30,8 +30,8 @@ AM_CPPFLAGS = -DLIBRARYBUILD \
 	-I$(top_srcdir)/src/libnurbs/internals \
 	-I$(top_srcdir)/src/libnurbs/interface \
 	-I$(top_srcdir)/src/libnurbs/nurbtess
-AM_CFLAGS = $(GL_CFLAGS) $(OSMESA_CFLAGS) $(WARNCFLAGS) $(VISIBILITY_CFLAGS)
-AM_CXXFLAGS = $(GL_CFLAGS) $(OSMESA_CFLAGS) $(WARNCXXFLAGS) $(VISIBILITY_CXXFLAGS)
+AM_CFLAGS = $(GL_CFLAGS) $(LIBGLVND_CFLAGS) $(OSMESA_CFLAGS) $(WARNCFLAGS) $(VISIBILITY_CFLAGS)
+AM_CXXFLAGS = $(GL_CFLAGS) $(LIBGLVND_CFLAGS) $(OSMESA_CFLAGS) $(WARNCXXFLAGS) $(VISIBILITY_CXXFLAGS)
 
 GL_includedir = $(includedir)/GL
 GL_include_HEADERS = \
@@ -130,7 +130,7 @@ libGLU_la_SOURCES =						\
 	src/libnurbs/nurbtess/sampleMonoPoly.cc			\
 	src/libnurbs/nurbtess/sampledLine.cc			\
 	src/libnurbs/nurbtess/searchTree.cc
-libGLU_la_LIBADD = $(GL_LIBS) $(OSMESA_LIBS)
+libGLU_la_LIBADD = $(GL_LIBS) $(LIBGLVND_LIBS) $(OSMESA_LIBS)
 libGLU_la_LDFLAGS = -version-number $(GLU_LIBRARY_VERSION) -no-undefined -export-symbols-regex '^glu'
 
 EXTRA_DIST =							\
diff --git a/configure.ac b/configure.ac
index f1bb7b1..e4555d6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -58,34 +58,52 @@ m4_ifndef([PKG_PROG_PKG_CONFIG],
   ACLOCAL="aclocal -I/other/macro/dir" before running autoreconf.])])
 PKG_PROG_PKG_CONFIG()
 
+AC_ARG_ENABLE(libglvnd,
+              AS_HELP_STRING([--enable-libglvnd],
+                [Enable use of libglvnd]),
+              [LIBGLVND="$enableval"],
+              [LIBGLVND=no])
+
 AC_ARG_ENABLE(osmesa,
               AS_HELP_STRING([--enable-osmesa],
                 [Enable use of OSMesa instead of libGL]),
               [OSMESA="$enableval"],
               [OSMESA=no])
 
-dnl Get the pkg-config definitions for libGL/OSMesa.  We include a fallback
-dnl path for implementations that don't provide a .pc file
-if test "x$OSMESA" = "xyes"; then
+dnl Get the pkg-config definitions for libglvnd/OSMesa/libGL.  We include a
+dnl fallback path for implementations that don't provide a .pc file
+AS_IF([test "x$LIBGLVND" = "xyes"], [
+    GLU_REQUIRES="libglvnd"
+    PKG_CHECK_MODULES(LIBGLVND, [opengl], [], [
+        AC_CHECK_HEADER([GL/gl.h],
+                        [],
+                        AC_MSG_ERROR([libglvnd GL not found]))
+        AC_CHECK_LIB([OpenGL],
+                     [glBegin],
+                     [GL_LIBS=-lOpenGL],
+                     AC_MSG_ERROR([libglvnd libOpenGL required]))
+    ])
+], [test "x$OSMESA" = "xyes"], [
     GLU_REQUIRES="osmesa"
     PKG_CHECK_MODULES(OSMESA, [osmesa], [], [
-          AC_CHECK_LIB([OSMesa],
-                   [glBegin],
-                   [OSMESA_LIBS=-lOSMesa],
-                   AC_MSG_ERROR([OSMesa required]))
-          ])
-else
+        AC_CHECK_LIB([OSMesa],
+                     [glBegin],
+                     [OSMESA_LIBS=-lOSMesa],
+                     AC_MSG_ERROR([OSMesa required]))
+    ])
+], [
     GLU_REQUIRES="gl"
     PKG_CHECK_MODULES(GL, [gl], [], [
-          AC_CHECK_HEADER([GL/gl.h],
-                  [],
-                  AC_MSG_ERROR([GL not found]))
-          AC_CHECK_LIB([GL],
-                   [glBegin],
-                   [GL_LIBS=-lGL],
-                   AC_MSG_ERROR([GL required]))
-          ])
-fi
+        AC_CHECK_HEADER([GL/gl.h],
+                        [],
+                        AC_MSG_ERROR([GL not found]))
+        AC_CHECK_LIB([GL],
+                     [glBegin],
+                     [GL_LIBS=-lGL],
+                     AC_MSG_ERROR([GL required]))
+    ])
+])
+
 AC_SUBST([GLU_REQUIRES])
 
 dnl Set up C warning and visibility flags.
-- 
cgit v1.2.1