spirv-wasm

Run SPIR-V shaders in WebAssembly

See demo at https://fhtr.org/spirv-wasm - uses WebAssembly Threads, so you may need to turn them on in chrome://flags or such.

More demos

These require WebAssembly SIMD enabled in chrome://flags. All running on the CPU.

• GLSL AOBench, pretty much a copy-paste from the ShaderToy version
• Animated ISPC Mandelbrot

Goal

Write low-effort code in one language, run safely in the browser at 50% of hardware peak performance.

For comparison, naive C++ achieves 1% of HW peak performance on a 16-core. If you include the GPU, it's closer to 0.1% of peak perf. Divide by amount of compute nodes available to you. Yes, yes, adding OpenMP #pragmas and doing hot spots in SoA intrinsics / ISPC, CUDA, and MPI does get you to 90%+ after much effort.

Contribute

Help! There's a lot of work to do! Estimated effort for the first pass: works OK for simple pipelines 100 commits, GPU integration 300 commits, job system 300 commits, simple distributed computing 200 commits, decent standard library 500 commits. Reaching something at the level "Hey you've got to try this, it's awesome for X" is 3000 commits. I've got roughly 200 commits per year to spend here... you do the math.

Try to get it running (use the Docker image), write some shaders, see how it goes.

Have a look at the issues and make some more.

Build

Requires Emscripten, glslangValidator, glm and spirv-cross.

Install Emscripten

The others are likely in your package manager.

brew install glslangValidator
brew install spirv-cross
brew install glm

Now you can build the shader:

source somewhere/emsdk/emsdk_env.sh
emmake make
serve

If everything went right, you can open http://localhost:5000/src/mandel.html and hopefully see a Mandelbrot fractal. Check the browser console for timings.

Debug information

You can make Emscripten emit source maps with the -g4 flag. You can make glslangValidator and the latest versions of spirv-cross emit line numbers like this:

glslangValidator -g -V -o mandel.spv mandel.comp
spirv-cross --cpp --emit-line-directives --output mandel.spv.cpp mandel.spv

Then you just have to hack the Emscripten source maps to map from the cpp to the compute shader line numbers.

Send a PR if you do!