mirror of
https://github.com/BinomialLLC/basis_universal.git
synced 2026-10-29 04:05:32 +00:00
Ben Polinsky
b15211474d
With the default DYNAMIC_EXECUTION=1, embind generates its invokers at runtime with new Function(). A Content-Security-Policy without 'unsafe-eval' blocks this, so the transcoder and encoder fail to start with an EvalError. Add two CMake options to webgl/transcoder and webgl/encoder: - NO_DYNAMIC_EXECUTION (default OFF) adds -s DYNAMIC_EXECUTION=0. - EMBIND_AOT (default ON, only used with NO_DYNAMIC_EXECUTION) adds -s EMBIND_AOT=1. This generates the invokers at build time, so embind calls stay as fast as with the default build. The default build does not change. The .wasm output is byte-identical in all configurations; only the JS glue changes. Fixes #464
29 lines
1.5 KiB
Markdown
29 lines
1.5 KiB
Markdown
`basisu_wrappers.cpp` contains our JavaScript API (implemented via [emscripten](https://emscripten.org/) bindings), which is a thin layer above our encoder and transcoder's C++ API's. As of Basis Universal v2.0 it supports optional WASM multithreading and WASM64.
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Prebuilt versions of `basis_transcoder.js` and `basis_transcoder.wasm` are included in the `build/` folder, and are sufficient for local demos. To build the transcoder yourself, first install emscripten ([tutorial](https://webassembly.org/getting-started/developers-guide/)) and cmake ([download](https://cmake.org/download/)). Then run:
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```shell
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cd webgl/transcoder/build/
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emcmake cmake ../
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make
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```
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### Strict Content-Security-Policy (no `unsafe-eval`)
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By default, the generated JavaScript glue uses `new Function()` to build its
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embind bindings at runtime. A Content-Security-Policy without `'unsafe-eval'`
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blocks this, and module startup fails with an `EvalError`. To build glue that
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never calls `eval()` or `new Function()`, add `-DNO_DYNAMIC_EXECUTION=ON`:
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```shell
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emcmake cmake ../ -DNO_DYNAMIC_EXECUTION=ON
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make
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```
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This adds `-s DYNAMIC_EXECUTION=0 -s EMBIND_AOT=1` to the link flags. The
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`.wasm` file does not change. `EMBIND_AOT` generates the bindings at build
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time, so JavaScript-to-WASM calls stay as fast as in the default build. The
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page still needs `'wasm-unsafe-eval'` in `script-src` to compile the
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WebAssembly module. Use `-DEMBIND_AOT=OFF` to get the smaller, generic
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bindings, which are slower per call.
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