[WIP] A third gfx example

[goddessfreya]

Depends on #2071 and #2052
PR checklist:

• make succeeds (on *nix)
• make reftests succeeds
• tested examples with the following backends:

[goddessfreya]

I'll reopen this when I work on more examples again.

[kvark]

Can we get around using the takeable-option and manually dropped things?

[goddessfreya]

We can get around manually dropping things by ordering the members in the struct definitions in the order we want to drop them. I feel, however, that manually drop helps document the order in which you should be dropping things. I think you'll agree that It would be annoying if changing the order of the members in a struct caused bugs.

As for takeable, no. The hal destroy functions want ownership of the struct members & drop only gets an &mut of the structs.

[kvark]

We can get around manually dropping things by ordering the members in the struct definitions in the order we want to drop them.

Do you really have to drop things in a specific order with HAL? AFAIK, Vulkan says destruction order can be arbitrary.

[goddessfreya]

Other than the swapchain, no. I removed all the ManuallyDrops and just made the swapchain Takeable.

[kvark]

Thank you!
I'm still not sure we need takeable_option magic though. Would the code be much worse if it had a few regular Option members of structs? In the worst case, we'll have something like as_mut().unwrap() in a place or two, but using a standard construct (Option) is way friendlier.

[goddessfreya]

@kvark You can compare the two versions and see which you prefer. I personally like Takeable (else I wouldn't have made it).

[kvark]

@zegentzy thank you, looks great! Let's fix the CI issues and get this merged.

[goddessfreya]

@kvark Done.

[kvark]

Bors r+

…

On Jul 20, 2018, at 21:56, Hal Gentz ***@***.***> wrote: @kvark Done. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or mute the thread.

[bors]

Build succeeded

• continuous-integration/travis-ci/push
• continuous-integration/appveyor/branch