gstreamer linking error (when using gstglfilter) - cmake

Question

When I build my gstreamer project using CMake I use the following CmakeLists.txt:
cmake_minimum_required(VERSION 3.16)
set(CMAKE_CXX_STANDARD 20)
include(FetchContent)
project(someproject)
find_package(PkgConfig REQUIRED)
pkg_check_modules(GST REQUIRED gstreamer-1.0>=1.4
gstreamer-sdp-1.0>=1.4
gstreamer-video-1.0>=1.4
gstreamer-plugins-base-1.0>=1.4
gstreamer-app-1.0>=1.4
gstreamer-gl-1.0>=1.4)
#some other calls to find_package
add_library(someproject "")
#add source directories
target_include_directories(GUI_lib PUBLIC include "${OTHER_FIND_PACKAGE_INCLUDE_DIRS}"
"${GST_INCLUDE_DIRS}")
target_link_libraries(someproject PUBLIC "${OTHER_FIND_PACKAGE_LIBS}" "${GST_LIBRARIES}" -lGL -lepoxy)
This results in the following error:
in function `drawCallback(_GstElement*, unsigned int, unsigned int, unsigned int, void*)':
undefined reference to `gst_gl_filter_get_type'
undefined reference to `gst_gl_filter_draw_fullscreen_quad'
I have searched my gstreamer install and verified that there exists a shared library that defines these symbols using the following snippet (asterisks for emphasis):
% readelf -s --wide /usr/lib/gstreamer-1.0/libgstopengl.so | rg gl_filter
121: 0000000000000000 0 FUNC GLOBAL DEFAULT UND gst_gl_filter_render_to_target_with_shader
* 242: 0000000000000000 0 FUNC GLOBAL DEFAULT UND gst_gl_filter_draw_fullscreen_quad
305: 0000000000000000 0 FUNC GLOBAL DEFAULT UND gst_gl_filter_add_rgba_pad_templates
421: 0000000000000000 0 FUNC GLOBAL DEFAULT UND gst_gl_filter_render_to_target
* 447: 0000000000000000 0 FUNC GLOBAL DEFAULT UND gst_gl_filter_get_type
470: 0000000000000000 0 FUNC GLOBAL DEFAULT UND gst_gl_filter_filter_texture
So, I added the following to my CMake file:
add_library(gstopenglextras SHARED IMPORTED)
set_target_properties(gstopenglextras PROPERTIES
IMPORTED_LOCATION "/usr/lib/gstreamer-1.0/libgstopengl.so")
I also changed the target_link_libraries call to:
target_link_libraries(someproject PUBLIC "${OTHER_FIND_PACKAGE_LIBS}" gstopenglextras "${GST_LIBRARIES}" -lGL -lepoxy)
Now I get the following linker error:
/usr/bin/ld: undefined reference to symbol 'gst_gl_filter_get_type'
/usr/bin/ld: /usr/lib/libgstgl-1.0.so.0: error adding symbols: DSO missing from command line
I've read some stuff on circular dependencies and I've tried adding "${GST_LIBRARIES}" before gstopenglextras. However, this does not change the error.
Any ideas?

Answer 1

target_link_libraries(
someproject
PUBLIC
"${OTHER_FIND_PACKAGE_LIBS}"
gstopenglextras
"${GST_LIBRARIES}"
-lGL
-lepoxy
gstgl-1.0
glib-2.0
gmodule-2.0
)
is the call you need to fix this issue.