Add PCL package

[planetmarshall]

Specify library name and version: pcl/1.11.0

• I've read the guidelines for contributing.
• I've followed the PEP8 style guides for Python code in the recipes.
• I've used the latest Conan client version.
• I've tried at least one configuration locally with the
  conan-center hook activated.

[Morwenn]

I made a basic PCL recipe for Conan some time ago and I've got a few comments regarding what differs:

• I decided to prefix many options with with_ or module_ to make it easier to make a difference between what drags in another optional dependency and what requires to build a PCL module. Also it avoids names like twod which isn't really pretty.

• I used the following code to handle either static or dynamic dependencies:

  self._cmake.definitions["PCL_SHARED_LIBS"] = self.options.shared
  self._cmake.definitions["PCL_BUILD_WITH_BOOST_DYNAMIC_LINKING_WIN32"] = self.options["boost"].shared
  self._cmake.definitions["PCL_BUILD_WITH_FLANN_DYNAMIC_LINKING_WIN32"] = self.options["flann"].shared
  if self.options.with_qhull:
      self._cmake.definitions["PCL_BUILD_WITH_QHULL_DYNAMIC_LINKING_WIN32"] = self.options["qhull"].shared

  I also had to add the following lines to the CMakeLists.txt to handle both static and dynamic flann. It's not pretty but it did the job:

  if (CONAN_COMPILE_DEFINITIONS_FLANN MATCHES "FLANN_STATIC")
      set(FLANN_USE_STATIC ON)
  endif()

• Apparently I didn't have to explicitly set any _ROOT CMake variable, I don't know whether they're useful here.

There's a number of reasons I had not proposed the recipe so far: Conan Center still lacks some of the main dependencies like VTK, which many people are likely to want. I considered adding a self.requires("vtk/x.x.x") that would require a package that doesn't exist but could be overriden but I don't think that it's something we want on Conan Center. Also I think that PCL config files export a bunch of CMake variables that wouldn't be automatically generated by Conan generators, and I'm not sure whether this is likely to cause problems.

[planetmarshall]

Thanks.

• Apparently I didn't have to explicitly set any _ROOT CMake variable, I don't know whether they're useful here.

I'm not sure how that would work, since PCL's find module looks explicitly for the QHull header file, and since no Conan-center packages are distributed with CMake or Pkgconfig files, I don't know how else it would find the QHull conan package.

[planetmarshall]

This seems to have been pending for a while. Any update on what it's doing? Is it just in a build queue? It would be useful to have visibility on the CI process for contributors.

[uilianries]

Thanks for all your effort. Please take a look on my review.

[planetmarshall]

Thanks for all your effort. Please take a look on my review.

Thanks for taking the time. I'll go through those as soon as I get a chance.

On the subject of options and dependencies - PCL is a large package that still has a few dependencies not provided by Conan (notably VTK).

One approach would be to remove options for which a conan dependency exists in the index (eg Qhull), but retain those that allow the end-user to still use the package without providing those dependencies themselves.

[jcar87]

Closed via #18389