Radium installation procedure

[hoshiryu]

As of now the Radium-Engine cannot be installed in a proper manner (relocatable libraries / executable).

Relocatable libraries:

When using the Radium-Engine as an external lib, one has to download/configure/compile it, but there is no install procedure, and the compiled Radium libraries are not relocatable. Though this feature is not top-priority for now, it would be nice to investigate the Radium-Engine installation in order to fulfill the modern CMake way of configuring projects. The main issue I found is about the external dependencies we rely on (submodules, e.g. OpenMesh, Assimp). For now, these external libraries are built and installed in the Bundle directory through the externalProject_add() command of cmake, and are linked against through their full installed path. Hence, when installing the Radium libraries I end up with 2 issues:

• first, I could not find a nicer way to re-install them along with the Radium libraries than just copying them to the desired location. This is problematic since their rpath is not updated accordingly.
• second, when using the Radium libraries from another project, the generator (make in my case) needs the external dependencies to be located in their install location (the one in the Bundle) which prevents the Radium libraries from being relocatable.

To fix that, I tried/thought about several things, but could not end up with a working solution:

• building the external libraries as static and link against them, so I had to add the flag -fPIC but I got some linker errors (not finished testing).
• link against the external libraries differently if in build or install interface but it didn't work (not finished testing).
• declaring imported libraries for the external libraries and link the Radium libraries to these, but imported libraries cannot be installed through cmake command install and when using to the Radium libraries from another project, the linker cannot find them.
• [undesirable] compile and install the external libraries at configure time to be able to call find_package (not finished testing).
• [undesirable] add the external libraries to the Radium project using add_subdirectory instead of externalProject_add (not tested).

Also to be mentioned, I didn't try using CPack, which might help solving this.

Relocatable executables:

Though I have been working on relocatable executables for my demonstrator, which is working fine, I had to somehow fix the resources issue mentionned in #337 . For this, I created a global variable in the Engine library that refers to the executable path (set to "./" by default), so that the executable (which overwrites this variable at launch) looks for Shaders and app-related resources folders by prefixing with this variable. I must also mention that my demonstrator is based on Qt and I used Qt-specific deployment tools to make it relocatable. I didn't try to deploy non-Qt executables, which might be more complex to do.

[nmellado]

Thanks for this detailed report. Can you refer to some repo/branch so we can have a look on your tests ?

[hoshiryu]

Of course, I thought I had put them: test_install*

[hoshiryu]

The build system also need some cleaning regarding cmake variables settings

[stale[bot]]

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