Example from guide build fails

[bcbroom]

I'm unable to run the example cargo run --release --example draw on macOS 10.15.7 (Catalina), and get

Compiling glsl-to-spirv v0.1.7
error: failed to run custom build command for `glsl-to-spirv v0.1.7`

Caused by:
  process didn't exit successfully: `/Users/broom/Documents/code/rust/nannou/target/release/build/glsl-to-spirv-6de94febe694eea4/build-script-build` (exit code: 101)
  --- stdout
  cargo:rerun-if-changed=build/glslangValidator.exe
  running: "cmake" "/Users/broom/.cargo/registry/src/github.com-1ecc6299db9ec823/glsl-to-spirv-0.1.7/glslang" "-DCMAKE_INSTALL_PREFIX=/Users/broom/Documents/code/rust/nannou/target/release/build/glsl-to-spirv-f1f9973f393be420/out" "-DCMAKE_C_FLAGS= -ffunction-sections -fdata-sections -fPIC -m64 -arch x86_64" "-DCMAKE_C_COMPILER=/usr/bin/cc" "-DCMAKE_CXX_FLAGS= -ffunction-sections -fdata-sections -fPIC -m64 -arch x86_64" "-DCMAKE_CXX_COMPILER=/usr/bin/c++" "-DCMAKE_ASM_FLAGS= -ffunction-sections -fdata-sections -fPIC -m64 -arch x86_64" "-DCMAKE_ASM_COMPILER=/usr/bin/cc" "-DCMAKE_BUILD_TYPE=Release"

  --- stderr
  fatal: not a git repository (or any of the parent directories): .git
  thread 'main' panicked at '
  failed to execute command: No such file or directory (os error 2)
  is `cmake` not installed?

  build script failed, must exit now', /Users/broom/.cargo/registry/src/github.com-1ecc6299db9ec823/cmake-0.1.45/src/lib.rs:894:5
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
warning: build failed, waiting for other jobs to finish...
error: build failed

I also tried

broom@Brian-Secondary-MBP nannou % rustup update
info: syncing channel updates for 'stable-x86_64-apple-darwin'
info: checking for self-updates

  stable-x86_64-apple-darwin unchanged - rustc 1.48.0 (7eac88abb 2020-11-16)

info: cleaning up downloads & tmp directories
broom@Brian-Secondary-MBP nannou % xcode-select --install
xcode-select: error: command line tools are already installed, use "Software Update" to install updates

[coka]

@bcbroom You need to install CMake. If you install CMake.app using the .dmg from that website, you can check out Tools > How to Install For Command Line Use in the menu bar for details on how to make sure that the cmake command is available from your shell.

@JoshuaBatty (sorry, don't know who to ping) Should CMake installation instructions be added to the guide?

[bcbroom]

That works - thanks.
I installed using brew install cmake

I think adding this to the directions would be a good idea, the directions for macOS say the Xcode command line tools are all you need.

[dimitre]

same issue here. +1 for adding on instructions

[mitchmindtree]

Thanks for digging into this folks - I believe it's only a couple of the examples that require glsl-to-spirv (and in turn cmake), however currently the way that the examples are collected in the repo requires that all their dependencies are to be built before one of them can be run which is a little unfortunate.

I don't remember off the top of my head exactly which dependency uses glsl-to-spirv, but ideally I think we replace it with naga which seems to be maturing fairly well lately (though I think it's GLSL front-end is in the process of getting a re-write). Using naga (a pure-rust shader translator) should remove the need for cmake altogether.

Similarly, the WIP update from wgpu 0.7 to 0.8 should remove the need for spirv-cross, a c++ dependency that was previously used to go from SPIRV -> Metal on macOS (also in favour of naga).