Creating KTX2 in wasm

[jocabola]

Is it possible to create a KTX2 texture from a source JPG or PNG using the libktx wasm in web? Or do I need to wrap the toktx command in node or other server-side technology to generate them? It seems like client machines will be usually more powerful and would make sense to do so, but I am stuck using the wasm module right now....

Thanks!

[jocabola]

Hello again,

Sorry to insist but anybody knows the answer to this? Is the toktx functionality exposed in the wasm lib or is this only intended for transcoding currently?

If KTX generation is possible with the wasm lib is there any documentation out there? I couldn't see any ktxTexture_Create or similar exposed in the JS lib.

Thanks,
Edu

[MarkCallow]

Sorry for the delay answering.

libktx.{js,wasm} is based on ktx_read, i.e the read only library. That is because that is all the wrapper currently supports. It is possible to compile the full libktx including encoders (not 100% sure about the ASTC encoder, definitely with the Basisu encoders) with Emscripten. There are two ways to use it:

1. Extend interface/js_binding/ktx_wrapper.cpp to support write functions and modify the wasm build to build the full library.
2. Write an app in c++, compile it too with Emscripten, and link it with the full libktx.

Because toktx is a command line program with no graphical UI, and it reads and writes files, I haven't seen any point compiling it to run in a browser as I expect quite a bit of further work is necessary make it usable. tests/loadtests/gl3loadtests can be compiled with Emscripten (as es3loadtests) and includes a test that runs the BasisU encoder. It runs in a browser.

I'd happily accept PRs to extend ktx_wrapper or make toktx usable in a browser or both. If you are tempted to do the latter, you should hold off for a month. toktx will be replaced soon with a new tool.

[jocabola]

Thank you so much for the clear answer. We have a temporary workaround for now. Will keep an eye on the upcoming new tool! Thank you!

[donmccurdy]

Is this answer still accurate today, with the v4.3 alpha release?

[MarkCallow]

Yes it is still accurate.

Work has been done to add a small number of create-related functions to the wrapper as part of a soon to be released project. As the work only adds the minimal functions needed by that project, the updated wrapper will remain as part of that project.

As I said before, I'd happily accept a PR to extend the wrapper to the full functionality of libktx.

[MarkCallow]

As of v4.4.0 the JS wrapper provides the full functionality of libktx. Download https://github.com/KhronosGroup/KTX-Software/releases/download/v4.4.0/KTX-Software-4.4.0-Web-libktx.zip. Use https://github.com/KhronosGroup/KTX-Software/releases/download/v4.4.0/KTX-Software-4.4.0-Web-libktx_read.zip if you only need read functionality.