Failed to run mesh-shading example

[voxelias]

Short info header:

• GFX version: master
• OS: Darwin Kernel Version 20.1.0 x86_64
• GPU: Intel(R) Iris(TM) Plus Graphics

RUST_BACKTRACE=1 cargo run --release --bin mesh-shading --features metal
    Finished release [optimized] target(s) in 0.11s
     Running `/Users/elias/Projects/gfx/target/release/mesh-shading`
AdapterInfo { name: "Intel(R) Iris(TM) Plus Graphics", vendor: 0, device: 0, device_type: IntegratedGpu }
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: MissingFeature', examples/mesh-shading/main.rs:219:18
stack backtrace:
   0: _rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::option::expect_none_failed
   3: mesh_shading::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[cwfitzgerald]

As far as I'm aware, metal has no support for mesh shaders, neither does the underlying intel hardware, so it makes sence that it cannot run mesh shaders.

[kvark]

RIght, mesh shaders are currently only supported by Vulkan backend on limited platforms. The error reported by the example is appropriate.

[voxelias]

If it is known and fails in the right place, maybe some explained panic! instead of the Result::unwrap() on an Err would make more sense.

[kvark]

Sure, a better error message would be nice there!