Add a version and alias name for Jolt library in CMake

[nouturnsign]

Could a version be added to the project? It would be helpful to be able to specify the version of Jolt in find_package.

Use case would be something like:

find_package(Jolt 5.2.0)

Also, could an ALIAS target be added for Jolt? e.g.

# ...
add_library(Jolt ${JOLT_PHYSICS_SRC_FILES})
add_library(Jolt::Jolt ALIAS Jolt)

I see that Jolt already exports with a namespace as in

	export(TARGETS Jolt
		NAMESPACE Jolt::
		FILE JoltConfig.cmake)

so it would be helpful to add a namespaced target for linking with Jolt when using add_subdirectory.

Use case would be something like:

add_subdirectory(vendor/JoltPhysics/Build)
target_link_libraries(my-library PRIVATE Jolt::Jolt)

Disclaimer: I am not good at CMake, but I see other projects do this. I can writeup a quick PR if it's relevant!

[jrouwe]

Hello,

I have not seen these constructs before and I can't really find useful information on them either.

What does adding a version number do? Is it only a check so that if you do find_package(Jolt 10.0.0) that you would get an error? Or does it do more?

W.r.t. ALIAS, I have not tested this but wouldn't:

add_subdirectory(vendor/JoltPhysics/Build)
target_link_libraries(my-library PRIVATE Jolt)

work equally well? Also I'm not sure if the export won't conflict with the ALIAS since they're both defining Jolt::Jolt?

[nouturnsign]

Re: version number, yes from my understanding, in the context of using CMake, it's useful so that find_package(Jolt 10.0.0 REQUIRED) would get an error if version 10.0.0 of Jolt was not found (REQUIRED would force an error; without REQUIRED, it would just not find the package). To add the version, it can be specified in the project command.

Re: ALIAS, yes that works equally well, but using a namespace appears to be a convention. No, it would not cause an error from my understanding. I see this in projects like spdlog and SDL. It's not always the case; I know GLFW does not.

[jrouwe]

Ok, I ran some quick tests:

add_subdirectory(vendor/JoltPhysics/Build)
target_link_libraries(my-library PRIVATE Jolt)

works fine, but I guess there's no problem with having an alias. So I added both suggestions in #1430.