Target "SofaCaribou.Python" links to target "Caribou::Python.Config" but the target was not found

[Ziemnono]

Hi @jnbrunet,
I tried to include your plugin into my plugin by doing:

find_package(Caribou REQUIRED)

hence I received the following error during the generate of the cmake-gui. I even tried to delete the line and build again but the same mistake happen every time..

CMake Error at /snap/cmake/1000/share/cmake-3.22/Modules/FindPython/Support.cmake:3316 (add_library):
  Target "SofaCaribou.Python" links to target "Caribou::Python.Config" but
  the target was not found.  Perhaps a find_package() call is missing for an
  IMPORTED target, or an ALIAS target is missing?
Call Stack (most recent call first):
  /snap/cmake/1000/share/cmake-3.22/Modules/FindPython.cmake:580 (__Python_add_library)
  applications/plugins/caribou/cmake/caribouTools.cmake:115 (python_add_library)
  applications/plugins/caribou/src/SofaCaribou/Python/CMakeLists.txt:53 (caribou_add_python_module)

Do you have an idea ?
Thanks !

[jnbrunet]

Hey @Ziemnono ,

Here's two examples to create a cmake project that depends on Caribou and Sofacaribou.

Let's suppose I have the following environment variable set:

$ export SOFA_ROOT=/opt/sofa/build/install 
$ export CARIBOU_ROOT=/opt/caribou/build/install

Note here that both variables point to the installation directory of both SOFA and caribou, and not the build directory. Hence if you have built them instead of downloading the binaries, you have to execute make install inside the build directory.

Linking a test executable against Caribou

CMakeLists.txt

cmake_minimum_required(VERSION 3.20)
project(test)

find_package(Caribou REQUIRED)
find_package(Eigen3 REQUIRED)

add_executable(test main.cpp)

target_link_libraries(test Caribou::Config Caribou::Geometry Eigen3::Eigen)

main.cpp

#include <Eigen/Dense>
#include <Caribou/constants.h>
#include <Caribou/Geometry/Triangle.h>
#include <iostream>

int main() {
        using namespace caribou;
        using Triangle = caribou::geometry::Triangle<_2D, Linear>;

        using LocalCoordinates = Triangle::LocalCoordinates;
        using WordCoordinates = Triangle::WorldCoordinates;

        Triangle t (
            WordCoordinates({50, 50}),
            WordCoordinates({60, 50}),
            WordCoordinates({55, 55})
        );

        auto center = t.center();
        std::cout << "(" << center[0] << ", " << center[1] << ")" << std::endl;
        return 0;
}

Compilation
Let /tmp/test be the directory that contains the two previous files. Make sure CARIBOU_ROOT is defined as before. Note that here SOFA_ROOT should not be necessary as SOFA is not use in this example.

$ cmake -S /tmp/test -B /tmp/test/build -DCMAKE_PREFIX_PATH=$CARIBOU_ROOT/lib/cmake 
-- The C compiler identification is AppleClang 13.0.0.13000029
-- The CXX compiler identification is AppleClang 13.0.0.13000029
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found PythonLibs: /usr/local/opt/python@3.9/Frameworks/Python.framework/Versions/3.9/lib/libpython3.9.dylib
-- Performing Test HAS_FLTO
-- Performing Test HAS_FLTO - Success
-- Performing Test HAS_FLTO_THIN
-- Performing Test HAS_FLTO_THIN - Success
-- Configuring done
-- Generating done
-- Build files have been written to: /tmp/test/build

$ cmake --build /tmp/test/build
[ 50%] Building CXX object CMakeFiles/test.dir/main.cpp.o
[100%] Linking CXX executable test
[100%] Built target test

$ /tmp/test/build/test
(55, 51.6667)

Linking a test plugin against SofaCaribou

This plugin contains an empty hyperelastic material.
CMakeLists.txt

cmake_minimum_required(VERSION 3.20)
project(MyCoolMaterial)

find_package(SofaCaribou REQUIRED)
find_package(SofaFramework REQUIRED)
find_package(Sofa.Config REQUIRED)
find_package(Sofa.Core REQUIRED)

find_package(Eigen3 REQUIRED)
add_library(${PROJECT_NAME} SHARED init.cpp MyCoolMaterial.cpp)

target_link_libraries(${PROJECT_NAME} Eigen3::Eigen Sofa.Config Sofa.Core SofaCaribou)

init.cpp

extern "C" {
     void        initExternalModule();
     const char* getModuleName();
     const char* getModuleVersion();
     const char* getModuleLicense();
     const char* getModuleDescription();
     const char* getModuleComponentList();
}

void initExternalModule() {}
const char* getModuleName() { return "test"; }
const char* getModuleVersion() { return "alpha 1.0"; }
const char* getModuleLicense() { return "TBD"; }
const char* getModuleDescription() { return ""; }
const char* getModuleComponentList() { return ""; }

MyCoolMaterial.cpp

#include <SofaCaribou/Material/HyperelasticMaterial.h>
#include <sofa/core/ObjectFactory.h>

class MyCoolMaterial : public SofaCaribou::material::HyperelasticMaterial<sofa::defaulttype::Vec3Types> {
    using Coord = typename sofa::defaulttype::Vec3Types::Coord;
    using Real  = typename Coord::value_type;
public:
    SOFA_CLASS(MyCoolMaterial, SofaCaribou::material::HyperelasticMaterial<sofa::defaulttype::Vec3Types>);

    /**
     * This is called just before the material is updated on every points (usually just before a Newton step).
     * It can be used to update some coefficients that will be used on material points (for example, compute
     * the parameters mu and lambda from the young modulus and poisson ratio given as data arguments).
     */
    void before_update() override {}

    /**
     * Get the strain energy density Psi from the right Cauchy-Green strain tensor C.
     *
     * Psi(E) = lambda/2 (tr(E))^2 + mu tr(E*E)
     *
     */
    Real
    strain_energy_density(const Real & /*J*/, const Eigen::Matrix<Real, 3, 3>  & /*C*/) const override {
        return 0;
    }

    /** Get the second Piola-Kirchhoff stress tensor from the right Cauchy-Green strain tensor C. */
    Eigen::Matrix<Real, 3, 3>
    PK2_stress(const Real & /*J*/, const Eigen::Matrix<Real, 3, 3>  & /*C*/) const override {
        static const auto Id = Eigen::Matrix<Real, 3, 3, Eigen::RowMajor>::Identity();
        return Id;
    }

    /** Get the jacobian of the second Piola-Kirchhoff stress tensor w.r.t the right Cauchy-Green strain tensor C. */
    Eigen::Matrix<Real, 6, 6>
    PK2_stress_jacobian(const Real & /*J*/, const Eigen::Matrix<Real, 3, 3> & /*C*/) const override {
        static const auto Id = Eigen::Matrix<Real, 6, 6, Eigen::RowMajor>::Identity();
        return Id;
    }
};


static int MyCoolMaterialClass = sofa::core::RegisterObject("A very cool hyperelastic material")
    .add< MyCoolMaterial >();

test.scn

<Node>
  <MyCoolMaterial template="Vec3d"/>
</Node>

Compilation
Let /tmp/test be the directory that contains the previous files. Make sure both SOFA_ROOT and CARIBOU_ROOT are defined as before.

$ cmake -S /tmp/test -B /tmp/test/build -DCMAKE_PREFIX_PATH=$CARIBOU_ROOT/lib/cmake 
- The C compiler identification is AppleClang 13.0.0.13000029
-- The CXX compiler identification is AppleClang 13.0.0.13000029
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found PythonLibs: /usr/local/opt/python@3.9/Frameworks/Python.framework/Versions/3.9/lib/libpython3.9.dylib
-- Performing Test HAS_FLTO
-- Performing Test HAS_FLTO - Success
-- Performing Test HAS_FLTO_THIN
-- Performing Test HAS_FLTO_THIN - Success
-- Configuring done
-- Generating done
-- Build files have been written to: /tmp/test/build

$ cmake --build /tmp/test/build
[33%] Building CXX object CMakeFiles/MyCoolMaterial.dir/init.cpp.o
[ 66%] Building CXX object CMakeFiles/MyCoolMaterial.dir/MyCoolMaterial.cpp.o
[100%] Linking CXX shared library libMyCoolMaterial.dylib
[100%] Built target MyCoolMaterial

$ SOFA_ROOT/bin/runSofa -l /tmp/test/build/libMyCoolMaterial.dylib /tmp/test/test.scn
(...)
[INFO]    [PluginManager] Loaded plugin: /tmp/test/build/libMyCoolMaterial.dylib
(...)

Let me know if you hit any difficulties.

[Ziemnono]

Hi @jnbrunet ,

Thank you very much for the 2 examples, really helpful and nicely explained!
The first example is running smoothly but an error occurs when I am running the second one.

arnaud@arnaud-Precision-5510:~/dev/CoolMaterial$ cmake -S . -B ./build -DCMAKE_PREFIX_PATH=$CARIBOU_ROOT/lib/cmake
-- The C compiler identification is GNU 9.3.0
-- The CXX compiler identification is GNU 9.3.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/lib/ccache/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/lib/ccache/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found PythonLibs: /usr/lib/x86_64-linux-gnu/libpython3.8.so
-- Performing Test HAS_FLTO
-- Performing Test HAS_FLTO - Success
CMake Error at /home/arnaud/dev/caribou/build/install/lib/cmake/SofaCaribou/SofaCaribouConfig.cmake:47 (find_package):
  By not providing "FindMKL.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "MKL", but
  CMake did not find one.

  Could not find a package configuration file provided by "MKL" with any of
  the following names:

    MKLConfig.cmake
    mkl-config.cmake

  Add the installation prefix of "MKL" to CMAKE_PREFIX_PATH or set "MKL_DIR"
  to a directory containing one of the above files.  If "MKL" provides a
  separate development package or SDK, be sure it has been installed.
Call Stack (most recent call first):
  CMakeLists.txt:4 (find_package)


-- Configuring incomplete, errors occurred!
See also "/home/arnaud/dev/CoolMaterial/build/CMakeFiles/CMakeOutput.log".

I think by default, SofaCaribou is built with MKL but couldn't be found by CMake, any idea ?
Thank you and have a nice day/evening !

UPDATE: By deactivating MKL option in the Caribou compilation, it is working :) But it still needs to be fixed for MKL, if you have any idea

[jnbrunet]

Hey @Ziemnono ,

PR #92 addressed this MKL issue. Updating Caribou's code should fix the error. Thanks a lot for reporting it!

J-N