iOS example

[bschwind]

From #214

This is essentially the triangle example, with some steps in a README describing how to build and run the example via Xcode.

I'm currently not pleased with the cargo setup I have, I needed to make the example its own project because I was building a library. I thought you could build examples as static libraries, but I couldn't get it to work. If someone could help, that would potentially simplify a lot.

Update: Got it working via the normal cargo example system, not sure why I had trouble before.

There are also some nastier issues when building, having to do with shaderc-sys and CMake. I had to manually edit a CMakeCache.txt file in order to make the build work it's described in the README. I need to investigate more on that.

The example runs and displays a triangle, however it eventually crashes with an error:

2019-10-01 01:21:24.865061+0900 ios-triangle[3636:293430] Metal GPU Frame Capture Enabled
2019-10-01 01:21:24.865982+0900 ios-triangle[3636:293430] Metal API Validation Enabled
thread '<unnamed>' panicked at 'winit iOS bug, file an issue: `EventHandler` unexpectedly started polling', /Users/brian/.cargo/registry/src/github.com-1ecc6299db9ec823/winit-0.20.0-alpha3/src/platform_impl/ios/app_state.rs:268:30
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
libc++abi.dylib: terminating with uncaught foreign exception

This is an issue with winit, perhaps it's not visible in the most recent version, I haven't tested enough yet.

I ran this with XCode 10 + iOS 12 on an iPhone SE at first, and it was crashing due to some metal command buffer calls.

Today I ran it with XCode 11 + iOS 13 and it eventually reaches the winit crash I described above.

[codecov-io]

Codecov Report

Merging #218 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #218   +/-   ##
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  Coverage   87.57%   87.57%           
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  Files           6        6           
  Lines         169      169           
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  Hits          148      148           
  Misses         21       21

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[bschwind]

Update: I rebased on the latest master, removed the exit after 5 seconds which I somehow hadn't noticed, and ran it again on iOS 13.

It works until I rotate the screen to landscape, then back to portrait. Everything freezes and I get:

2019-10-06 19:37:08.305133+0900 ios-triangle[12625:1316008] Execution of the command buffer was aborted due to an error during execution. Discarded (victim of GPU error/recovery) (IOAF code 5)
2019-10-06 19:37:08.305534+0900 ios-triangle[12625:1316008] Execution of the command buffer was aborted due to an error during execution. Discarded (victim of GPU error/recovery) (IOAF code 5)
2019-10-06 19:37:08.305937+0900 ios-triangle[12625:1316008] Execution of the command buffer was aborted due to an error during execution. Discarded (victim of GPU error/recovery) (IOAF code 5)
2019-10-06 19:37:08.306073+0900 ios-triangle[12625:1316008] Execution of the command buffer was aborted due to an error during execution. Discarded (victim of GPU error/recovery) (IOAF code 5)
2019-10-06 19:37:08.306226+0900 ios-triangle[12625:1316008] Execution of the command buffer was aborted due to an error during execution. Discarded (victim of GPU error/recovery) (IOAF code 5)
2019-10-06 19:37:08.306333+0900 ios-triangle[12625:1316008] Execution of the command buffer was aborted due to an error during execution. Discarded (victim of GPU error/recovery) (IOAF code 5)

Screenshot of it working, looks kinda crap. Maybe there's a DPI issue with winit or something.

[simlay]

This is pretty cool. I kinda think you should put some of the steps you've got in the readme in a makefile and then put those as rules in the CI. The CMakeCache issue really is grossest of the setup steps.

[simlay]

I've been adding examples with the Xcode project in them as seen in rust-windowing/glutin#1233. I admit that it's a bit annoying to setup but you can also make it run in CI that way.

[bschwind]

I'll have to take a look at that, I haven't worked on this in quite awhile so I need to refresh my memory.