Matlab Wrapper Function 'matlab_wrap' Not Working For GPMP2

[mattking-smith]

Description

I am trying to use the wrap repository to generate the MATLAB interface to the GPMP2 repository, but I am running into an error when trying to run the matlab_wrap() function. I have been able to create this MATLAB interface with the help of @gchenfc (which I currently have working on a development computer), but that was some time ago and I am worried possibly there may have been changes to the wrapper implementation.

Steps to reproduce error

1. In the command prompt run:

   git clone https://github.com/gtrll/gpmp2.git 
   cd gpmp2 && mkdir build && cd build
   sudo cmake -DGPMP2_BUILD_MATLAB_TOOLBOX:=ON ..

2. However, I found that that this produced and error due to and outdated CMakeLists.txt file. Specifically, in lines 66-74 of the GPMP2 CMakeLists.txt has:

   # Wrapping to MATLAB
   if(GPMP2_BUILD_MATLAB_TOOLBOX)
   # wrap
   include(GtsamMatlabWrap)
   wrap_and_install_library(gpmp2.h ${PROJECT_NAME} "${CMAKE_CURRENT_SOURCE_DIR}" "")
   
   # install matlab functions and scripts
   add_subdirectory(matlab)
   endif()

   So I changed these lines in the CMakeLists.txt file to the following:

   
   find_package(gtwrap REQUIRED)

Wrapping to MATLAB

if(GPMP2_BUILD_MATLAB_TOOLBOX)

include(MatlabWrap) matlab_wrap(gpmp2.h ${PROJECT_NAME} "${CMAKE_CURRENT_SOURCE_DIR}" "" "")

install matlab functions and scripts

add_subdirectory(matlab) endif()

However, after making this change, calling `sudo cmake -DGPMP2_BUILD_MATLAB_TOOLBOX:=ON ..` in the command prompt results in the error during the cmake generation:

CMake Error at CMakeLists.txt:71 (matlab_wrap): matlab_wrap Function invoked with incorrect arguments for function named: matlab_wrap

## Outstanding Question
Am I using the `matlab_wrap()` function incorrectly? On my computer with the work GPMP2 + GTSAM + Matlab toolbox, my CMakeLists.txt file appears as the way I modified the CMakeLists.txt. 

Has there been a modification to the way I am suppose to use `matlab_wrap()`?

Any thoughts on this @gchenfc?

## Environment
Linux OS: Ubuntu 20.04
MATLAB version: 2021a 
Standard GPMP2 + MATLAB Toolbox build.

[varunagrawal]

Yes the CMake function has changed considerably. You should read the docstrings in the CMake file and see what needs to be updated. Should be pretty straightforward.

[varunagrawal]

I believe there is another argument added, which was done to support multiple .i files in Matlab.

This is pretty much a GPMP issue, but this issue can help us figure out various kinks.

[varunagrawal]

wrap_and_install_library(gpmp2.h ${PROJECT_NAME} "${CMAKE_CURRENT_SOURCE_DIR}" "") should be updated to: matlab_wrap(gpmp2.h ${PROJECT_NAME} "gtsam;${PROJECT_NAME}" "" "" "")

[mattking-smith]

wrap_and_install_library(gpmp2.h ${PROJECT_NAME} "${CMAKE_CURRENT_SOURCE_DIR}" "") should be updated to: matlab_wrap(gpmp2.h ${PROJECT_NAME} "gtsam;${PROJECT_NAME}" "" "" "")

Thank you very much for this response, I'll try it out.

[mattking-smith]

I believe there is another argument added, which was done to support multiple .i files in Matlab.

This is pretty much a GPMP issue, but this issue can help us figure out various kinks.

I am going to keep playing around with this so I can ultimately make a PR on the GPMP2 repository so it can work in harmony with the wrap code as is.

[mattking-smith]

wrap_and_install_library(gpmp2.h ${PROJECT_NAME} "${CMAKE_CURRENT_SOURCE_DIR}" "") should be updated to: matlab_wrap(gpmp2.h ${PROJECT_NAME} "gtsam;${PROJECT_NAME}" "" "" "")

So I tried building with the CMakeLists.txt as you suggested and I was given the following error:

sudo cmake -DGPMP2_BUILD_MATLAB_TOOLBOX:=ON ..
.
.
.
-- Installing Matlab Toolbox to 
CMake Error at /usr/local/lib/cmake/gtwrap/MatlabWrap.cmake:360 (install):
  install DIRECTORY given no DESTINATION!
Call Stack (most recent call first):
  /usr/local/lib/cmake/gtwrap/MatlabWrap.cmake:93 (install_wrapped_library_internal)
  /usr/local/lib/cmake/gtwrap/MatlabWrap.cmake:68 (wrap_and_install_library)
  CMakeLists.txt:73 (matlab_wrap)

CMake Error at /usr/local/lib/cmake/gtwrap/MatlabWrap.cmake:365 (install):
  install TARGETS given no LIBRARY DESTINATION for module target
  "gpmp2_matlab_wrapper".
Call Stack (most recent call first):
  /usr/local/lib/cmake/gtwrap/MatlabWrap.cmake:93 (install_wrapped_library_internal)
  /usr/local/lib/cmake/gtwrap/MatlabWrap.cmake:68 (wrap_and_install_library)
  CMakeLists.txt:73 (matlab_wrap)

So then I tried running the command: sudo cmake -DGPMP2_BUILD_MATLAB_TOOLBOX:=ON -DGTSAM_TOOLBOX_INSTALL_PATH= $HOME/gpmp2_toolbox .. But this did not make a difference and I ended up with the same error. So finally I tried manually editing the CMakeCashe.txt file generated by the CMakeLists.txt file because I saw that the GTSAM toolbox path was not set, i.e. GTSAM_TOOLBOX_INSTALL_PATH:= to the following: GTSAM_TOOLBOX_INSTALL_PATH:PATH=/home/matt/gpmp2_toolbox, but this again did not fix the issue.

Any idea what arguments I am missing here?

[gchenfc]

I think the arguments are ok, just the cmake variable should be WRAP_TOOLBOX_INSTALL_PATH instead of GTSAM_TOOLBOX_INSTALL_PATH. You can check in gtsam's matlab.cmake for reference:

https://github.com/borglab/gtsam/blob/866d6b1fa1a68a8f4afdb084178fda07493d914d/matlab/CMakeLists.txt#L25-L34

if(NOT GTSAM_TOOLBOX_INSTALL_PATH)
  set(GTSAM_TOOLBOX_INSTALL_PATH "${CMAKE_INSTALL_PREFIX}/gtsam_toolbox")
endif()

set(WRAP_MEX_BUILD_STATIC_MODULE ${GTSAM_MEX_BUILD_STATIC_MODULE})
set(WRAP_BUILD_MEX_BINARY_FLAGS ${GTSAM_BUILD_MEX_BINARY_FLAGS})
set(WRAP_TOOLBOX_INSTALL_PATH ${GTSAM_TOOLBOX_INSTALL_PATH})
set(WRAP_CUSTOM_MATLAB_PATH ${GTSAM_CUSTOM_MATLAB_PATH})
set(WRAP_BUILD_TYPE_POSTFIXES ${GTSAM_BUILD_TYPE_POSTFIXES})

Perhaps you can add something similar in gpmp2:

if(NOT GPMP2_TOOLBOX_INSTALL_PATH)
  set(GPMP2_TOOLBOX_INSTALL_PATH "${CMAKE_INSTALL_PREFIX}/gpmp2_toolbox")
endif()

set(WRAP_TOOLBOX_INSTALL_PATH ${GTSAM_TOOLBOX_INSTALL_PATH})

By the way just for future debugging tips, if you look at MatlabWrap.cmake around line 360, you'll see that a little bit earlier it says message(STATUS "Installing Matlab Toolbox to ${WRAP_TOOLBOX_INSTALL_PATH}") and you can see in your output this is an empty string. Then in line 360 it's using DESTINATION ${WRAP_TOOLBOX_INSTALL_PATH} so this is cmake's INSTALL command complaining that you didn't give a destination (empty string)

[mattking-smith]

By the way just for future debugging tips, if you look at MatlabWrap.cmake around line 360, you'll see that a little bit earlier it says message(STATUS "Installing Matlab Toolbox to ${WRAP_TOOLBOX_INSTALL_PATH}") and you can see in your output this is an empty string. Then in line 360 it's using DESTINATION ${WRAP_TOOLBOX_INSTALL_PATH} so this is cmake's INSTALL command complaining that you didn't give a destination (empty string)

Noting this comment, I have successfully been able to use the current wrapper library with GPMP2 to wrap it into the MATLAB environment. However before we close this issue, I just want to make sure that the MATLAB segmentation fault I am experiencing (outlined in https://github.com/gtrll/gpmp2/issues/54) is not due to the wrapper, but on the GPMP2 side of things.

If either of you could check out the steps I outline in https://github.com/gtrll/gpmp2/issues/54 and the code I had posted in https://github.com/gtrll/gpmp2/pull/55 due to compiling issues definition changes in GTSAM's Eigen and Pose Transform, I'd appreciate it. Again, doing so would allow us to close this issue.

[mattking-smith]

I have been able to successfully wrap and rebuild GPMP2 with this current wrapper version. I am going to close this issue, as the segmentation faults were a result of a change in the gpmp2.h file between different versions, as noted in https://github.com/gtrll/gpmp2/issues/54.

[varunagrawal]

Amazing stuff! @gchenfc is the man and soon @mattking-smith will be our resident Matlab wrapper expert. 😄