[imgui-sfml] Force imgui-sfml to be a static library

[JackBoosY]

Force imgui-sfml to be a static library to avoid the issue of loading global variables in imgui twice.

Related: #9660.

[VincentZalzal]

I was one of those affected by issue #9660.

I tried this PR and it indeed fixes the crash.

There is one new small annoyance though. On Windows (at least), I now get link errors unless I add opengl32.lib to my project, which was not required when this was a dynamic library. I'm not sure if this is to be expected or if there is a way to automatically link to opengl32.lib too using vcpkg. I tested with VS2019 in Debug x64 configuration.

Sample of link errors:

1>ImGui-SFML.lib(imgui-SFML.cpp.obj) : error LNK2019: unresolved external symbol __imp_glBindTexture referenced in function "void __cdecl `anonymous namespace'::RenderDrawLists(struct ImDrawData *)" (?RenderDrawLists@?A0x823403ac@@YAXPEAUImDrawData@@@Z)
1>ImGui-SFML.lib(imgui-SFML.cpp.obj) : error LNK2019: unresolved external symbol __imp_glBlendFunc referenced in function "void __cdecl `anonymous namespace'::RenderDrawLists(struct ImDrawData *)" (?RenderDrawLists@?A0x823403ac@@YAXPEAUImDrawData@@@Z)
1>ImGui-SFML.lib(imgui-SFML.cpp.obj) : error LNK2019: unresolved external symbol __imp_glColorPointer referenced in function "void __cdecl `anonymous namespace'::RenderDrawLists(struct ImDrawData *)" (?RenderDrawLists@?A0x823403ac@@YAXPEAUImDrawData@@@Z)

[JackBoosY]

@VincentZalzal The issue that the system library is not automatically added after integration using the msvc project(sln/vcxproj) is currently unresolved. So you need to add them manually now.

[VincentZalzal]

@JackBoosY That's ok, it's still a lot better to be able to use vcpkg to handle all the rest!

[JackBoosY]

@Neumann-A At present, x64-linux is used to generate static libraries by default. If there is a dynamic library in lib, it must be a port bug.

[Neumann-A]

there is x64-osx-dynamic in the community triplets so somebody adding x64-linux-dynamic is not that far away. Also having vcpkg_check_linkage(ONLY_DYNAMIC_LIBRARY) in x64-linux won't trigger an error since it is perfectly allowed by vcpkg since VCPKG_CRT_LINKAGE is dynamic in x64-linux.

[ras0219-msft]

The consuming package should not need to care about whether SFML is static or dynamic -- we should introduce a vcpkg-cmake-wrapper in the sfml package that resolves this issue

[JackBoosY]

@ras0219-msft
Here, SFML_STATIC_LIBRARIES is forced to be BUILD_SHARED_LIBS, which causes sfml to be associated with imgui-sfml build type. So I think it needs to be removed here.

Since vcpkg_check_linkage changes the value of VCPKG_LIBRARY_LINKAGE, if we set this value in vcpkg-cmake-wrapper, we cannot use VCPKG_LIBRARY_LINKAGE to determine what VCPKG_LIBRARY_LINKAGE should be set to.

[JackBoosY]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[JackBoosY]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[JackBoosY]

@strega-nil Please review this PR.

Thanks.

[strega-nil]

Cool, thanks @JackBoosY :)

[cenit]

This has been merged broken despite @Neumann-A review... :(

[JackBoosY]

@Neumann-A @cenit I will continue to fix this issue.

[strega-nil]

oh shoot, I'm sorry -.-