From: Chow Loong Jin <hyperair@debian.org>
Date: Sun, 7 Jun 2015 09:54:37 +0800
Subject: Add missing X11 libraries when using GLX

Forwarded: https://github.com/openscad/openscad/issues/1355

---
 tests/CMakeLists.txt | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 7365674..2ae12c1 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -617,6 +617,8 @@ elseif(UNIX)
 	set(OFFSCREEN_CTX_SOURCE "OffscreenContextGLX.cc" CACHE TYPE STRING)
 	set(OFFSCREEN_IMGUTILS_SOURCE "imageutils-lodepng.cc" CACHE TYPE STRING)
 	set(PLATFORMUTILS_SOURCE "PlatformUtils-posix.cc" CACHE TYPE STRING)
+	find_package(X11 REQUIRED)
+	set(OPENGL_3RD_PARTY_LIBS ${X11_LIBRARIES})
 elseif(WIN32)
 	message(STATUS "Offscreen OpenGL Context - using Microsoft WGL")
 	set(OFFSCREEN_CTX_SOURCE "OffscreenContextWGL.cc" CACHE TYPE STRING)
@@ -770,6 +772,7 @@ endif()
 
 add_library(tests-offscreen STATIC ${OFFSCREEN_SOURCES})
 set_target_properties(tests-offscreen PROPERTIES COMPILE_FLAGS "${ENABLE_OPENCSG_FLAG} -DENABLE_CGAL ${CGAL_CXX_FLAGS_INIT}")
+target_link_libraries(tests-offscreen ${OPENGL_LIBRARIES} ${OPENGL_3RD_PARTY_LIBS})
 
 #
 # modulecachetest
