CMake + Dawn + Emscripten Build Refactor

[MichealReed]

We are now building the latest dawn. Specific commits can be pinned by adding a commit hash in cmake/gpu.cmake.

git fetch --depth=1 https://dawn.googlesource.com/dawn <commit hash>

• Removes dependency on external webgpu dependency
• Builds and links gpu.cpp + dawn in cmake/gpu.cmake.
• See cmake/example and the CMakeLists.txt files in most examples to easily link in other projects.
• Fixes a MSVC min/max overload problem in the render example.

Please try a few examples on other platforms and let me know if there are any issues 👍

From examples/hello_world
cmake -S . build/ -DCMAKE_BUILD_TYPE=Release

cmake --build build/ --config Release

[MichealReed]

With the new commits, all the examples should compile for emscripten and output files in the build folder for js, wasm, and html.

@austinvhuang let me know if you are cool with changing the import to "webgpu.h" vs "webgpu/webgpu.h". This makes CMake life easier as none of the generation from dawn outputs as "webgpu/webgpu.h".

I needed to also rename the main function in half.cpp. Since this is included via gpu.hpp it causes conflicts with the main from the run program in examples. With gpu.cpp being a library we should avoid any use of main within included files.

Try it with:

cd examples/hello_world
emcmake cmake -S . -B ./build_web -DCMAKE_BUILD_TYPE=Release
cmake --build build_web --config Release
python3 -m http.server 8080 --d build_web

• This builds Dawn's version of emscripten, https://github.com/google/dawn/tree/main/src/emdawnwebgpu. You must change https://dawn-review.googlesource.com/c/dawn/+/225514/2/src/emdawnwebgpu/CMakeLists.txt as shown in this PR until the PR lands.
• emsdk + emscripten required.
• You should use emscripten 4+ with emsdk install latest and emsdk activate latest.
• Make sure the EMSDK env variable is set on the build machine.

[austinvhuang]

With the new commits, all the examples should compile for emscripten and output files in the build folder for js, wasm, and html.

@austinvhuang let me know if you are cool with changing the import to "webgpu.h" vs "webgpu/webgpu.h". This makes CMake life easier as none of the generation from dawn outputs as "webgpu/webgpu.h".

I needed to also rename the main function in half.cpp. Since this is included via gpu.hpp it causes conflicts with the main from the run program in examples. With gpu.cpp being a library we should avoid any use of main within included files.

Try it with:

cd examples/hello_world emcmake cmake -S . -B ./build_web -DCMAKE_BUILD_TYPE=Release cmake --build build_web --config Release python3 -m http.server 8080 --d build_web

• This builds Dawn's version of emscripten, https://github.com/google/dawn/tree/main/src/emdawnwebgpu. You must change https://dawn-review.googlesource.com/c/dawn/+/225514/2/src/emdawnwebgpu/CMakeLists.txt as shown in this PR until the PR lands.
• emsdk + emscripten required.
• You should use emscripten 4+ with emsdk install latest and emsdk activate latest.
• Make sure the EMSDK env variable is set on the build machine.

Replying here for visibility - but as discussed in discord, let's try the "webgpu.h" w/o the path. There's probably some fixes in the Makefiles but we can workshop that in the dev branch before merging to main.