Added option to build against the system copy of GLM.

INSTALL

@@ -62,8 +62,14 @@ If you already have these fonts, you can configure Gource to use them with:
 
     ./configure --enable-ttf-font-dir=/path/to/freefont/
 
-Gource includes a copy of the TinyXML library. To make Gource build against
-the system library of TinyXML use:
+Gource includes a copy of the GLM header-only library due to backwards
+incompatible changes in the version most recently packaged by Debain.
+To build against the system version of GLM use:
+
+    ./configure --with-glm
+
+Gource includes a copy of TinyXML. To build against the system version of the
+library use:
 
     ./configure --with-tinyxml
 

Makefile.am

@@ -55,7 +55,11 @@ gource_SOURCES = \
 	src/user.cpp \
 	src/zoomcamera.cpp
 
-AM_CPPFLAGS = -I src/core/glm -DSDLAPP_RESOURCE_DIR=\"$(pkgdatadir)\"
+AM_CPPFLAGS = -DSDLAPP_RESOURCE_DIR=\"$(pkgdatadir)\"
+
+if USE_BUNDLED_GLM
+AM_CPPFLAGS += -I src/core/glm
+endif
 
 dist_pkgdata_DATA = data/beam.png data/bloom.tga data/bloom_alpha.tga data/file.png data/user.png data/gource.style
 

configure.ac

@@ -58,8 +58,15 @@ AC_ARG_ENABLE(ttf-font-dir,[AS_HELP_STRING([--enable-ttf-font-dir=DIR],[director
 AM_CONDITIONAL([FONTDIR], [test "x$gourcefontdir" != "x"])
 AC_SUBST(gourcefontdir)
 
-#GLM
-AC_CHECK_FILE(src/core/glm/glm/glm.hpp,, AC_MSG_ERROR(src/core/glm submodule not found. Please re-install or run ./autogen.sh))
+#see if building against system GLM library
+use_glm_system_library=no
+AC_ARG_WITH(glm, AC_HELP_STRING([--with-glm], [Use system installed GLM header-only library]), use_glm_system_library=$withval)
+if test "x$use_glm_system_library" = "xyes"; then
+    AC_CHECK_HEADER([glm/glm.hpp],, AC_MSG_ERROR(GLM header-only library was required but not found))
+else
+    AC_CHECK_FILE(src/core/glm/glm/glm.hpp,, AC_MSG_ERROR(src/core/glm submodule not found. Please re-install or run ./autogen.sh))
+fi
+AM_CONDITIONAL(USE_BUNDLED_GLM, test "x$use_glm_system_library" != "xyes")
 
 #see if building against system TinyXML library
 use_tinyxml_system_library=no