Hi Marcus,


On Wed, Jul 10, 2013 at 12:59 PM, Marcus Liebhardt <
marcus.liebhardt@yujinrobot.com> wrote:

>
> On Wed, Jul 10, 2013 at 6:39 PM, Marcus Liebhardt <
> marcus.liebhardt@yujinrobot.com> wrote:
>
>> Hey guys,
>> It's me again. Sorry for the high traffic.
>>
>> I released the openni_tracker and the source build works fine. However,
>> when building the deb, orocos-kdl can't be found.
>>
>> CMake Error at /opt/ros/hydro/share/catkin/cmake/catkinConfig.cmake:72 (find_package):
>>   Could not find a configuration file for package orocos_kdl.
>>
>>   Set orocos_kdl_DIR to the directory containing a CMake configuration file
>>   for orocos_kdl.  The file will have one of the following names:
>>
>>     orocos_kdlConfig.cmake
>>     orocos_kdl-config.cmake
>>
>> Call Stack (most recent call first):
>>   CMakeLists.txt:3 (find_package)
>>
>>
>> So, I started looking for the cause of this and found this seemingly
>> related issue involving the geometry stack:
>> https://github.com/ros/geometry/issues/11. The respective fix treats
>> orocos-kdl as a plain Cmake package instead of a catkin
>> package. Unfortunately, when applying this patch to the openni_tracker, my
>> local source build can't find the orocos-kdl library it tries to link to:
>>
>> Linking CXX executable
>> /opt/sandbox_workspace/devel/lib/openni_tracker/openni_tracker
>> /usr/bin/ld: cannot find -lorocos-kdl
>> collect2: ld returned 1 exit status
>> make[2]: ***
>> [/opt/sandbox_workspace/devel/lib/openni_tracker/openni_tracker] Error 1
>>
>> Again I started off to find hints for the cause of this. I took a look
>> at orocos_kdl-config.cmake and even the package config file, but nothing
>> seems suspicious to me. However, I must say that I don't have lots of CMake
>> experience. So this is harder for me than Korean. 0o
>>
>> One thing I noticed though is that the CMake log output about orocos-kdl
>> doesn't show any linker flags:
>>
>> Looking for KDL in: /opt/ros/hydro
>> -- checking for one of the modules 'orocos_kdl'
>>    Includes in: /opt/ros/hydro/include;/usr/include/eigen3
>> Compiler flags: -I/opt/ros/hydro/include;-I/usr/include/eigen3
>>    Libraries: orocos-kdl
>>    Libraries in: /opt/ros/hydro/lib
>>    Linker flags :
>>    Defines:
>>
>> I will keep looking further into this. But any hints, tips and help is
>> highly appreciated!
>>
>
> Joder! I think, I have found the missing piece - it's called
> "link_directories()". I shouldn't have looked only at that pull request,
> but at the newest version of the mentioned CMakeLists example.
>
> I'm still a bit confused though. I can't remember needing this
> "link_directories" addition so far. Furthermore, the ROS wiki even
> recommends not to use it, since target_link_libraries() should suffice for
> catkin and plain cmake packages - which is the case here (
> http://ros.org/wiki/catkin/CMakeLists.txt#Include_Paths_and_Library_Paths
> ).
>
> Could someone shed some light on this please?
>
>
AFAIK:

In most cases find_package(package_name) will fill
${package_name_LIBRARIES) with the full path of the libraries in which case
you do not need the link_directories statement. Although in some cases this
might not be true, and ${packag_name_LIBRARIES} only contains the libnames
without any path which seems to be the case with orocos-kdl:

taken from the orocos_kdl-config.cmake:

message("   Includes in: ${orocos_kdl_INCLUDE_DIRS}")
message(    "Compiler flags: ${orocos_kdl_CFLAGS}")
 message("   Libraries: ${orocos_kdl_LIBRARIES}")
message("   Libraries in: ${orocos_kdl_LIBRARY_DIRS}")
message("   Linker flags : ${orocos_kdl_LD_FLAGS}")
message("   Defines: ${orocos_kdl_DEFINES}")

This is the result of the use of pkgconfig in the orocos_kdl-config.cmake
to fill in these flags. If this is considered as a bug by someone please
file a bug report on bugs.orocos.org to have it resolved ;)


> Thanks again and sorry for the spam,
> Marcus
>
>
Ruben



>
>
>>
>> Thanks for reading,
>> Marcus
>>
>>
>>


-- 
Ruben Smits, Phd
Chief Technology Officer
Intermodalics BVBA
+32479511786
www.intermodalics.eu