emscripten | Emscripten : An LLVM-to-WebAssembly Compiler | Compiler library

i had the same issue. i had this compiler setting:

First thing to realize, is that decent Browsers currently implement only WebGL 1.0 (based on OpenGL ES 2.0) and WebGL 2.0 (based on OpenGL ES 3.0). So that Emscripten SDK may implement only features presented by WebGL 2.0 + extensions, and, unfortunately, Compute Shaders are not presented in any way in WebGL (and there are no more plans to add this functionality in future).

By the way, WebGL 2.0 support has been added to Safari 15 (iOS 15) only this (2021) year, so that even OpenGL ES 2.0 will not work on all devices.

I notice that there is an OpenGL ES 3.1 header in the emscripten

The extra headers are there not because Emscripten implements all of them, but because this is a common way to distribute OpenGL ES 3.x headers that existing applications may rely on to conditionally load / use OpenGL ES 3.x functions at runtime, when they available.

The documentation says that OpenGL ES3 is supported if I specify -s FULL_ES3=1 (which I am doing).

I think that documentation is more or less clear about what FULL_ES3=1 adds:

To enable OpenGL ES 3.0 emulation, specify the emcc option -s FULL_ES3=1 when linking the final executable (.js/.html) of the project. This adds emulation for mapping memory blocks to client side memory.

There is no word about OpenGL ES 3.1 here, nor a reason to expect a wonder from Emscripten, as I can barely imagine a reasonable hardware-accelerated way to emulate things like Compute Shaders on top of OpenGL ES 3.0. And software emulation would be certainly of no use for most applications.

WebGPU 1.0 that promised to appear mid '2022, is more capable than WebGL 2.0. So that WebGPU developers already see that at one time native WebGL 2.0 implementation in the Browsers could be replaced by a WebAssembly module implementing this legacy API on top of WebGPU - but in some very distant future. The same could also bring OpenGL ES 3.1/3.2 features to Emscripten SDK - at least theoretically, if somebody will be still interested to work on this.

Based on documentation:

By default, exception catching is disabled in Emscripten.

You have to enable it with the -fexceptions argument.

The video has frame rate of 25fps, and not 24fps:

After putting the correct value it works ok: demo
The VideoFrame api heavily relies on FPS provided by you. You can find FPS of your videos offline and send as metadata along with stop frames from server.

The site videoplayer.handmadeproductions.de uses window.requestAnimationFrame() to get the callback.

There is a new better alternative to requestAnimationFrame. The requestVideoFrameCallback(), allows us to do per-video-frame operations on video.
The same functionality, you domed in OP, can be achieved like this:

I would go about this using Qt's model-view-controller (delegate) paradigm. That is, your C++ code should expose some list-like Q_PROPERTY of channel status objects, which in turn expose their own data as properties. This can be done using a QQmlListProperty, as demonstrated here.

However, if the list itself is controlled from C++ code -- that is, the QML code does not need to directly edit the model, but only control which ones are shown in the view and possibly modify existing elements -- then it can be something simpler like a QList of QObject-derived pointers. As long as you do emit a signal when changing the list, this should be fine:

You will have a hard time trying to compile a whole library by invoking the Emscripten compiler on individual translation units; the encoder is not entirely contained in just one file. You need to engage the build system to build the full library.

Fortunately for you, much of the work in porting the library to WebAssembly has already been done; there is even a README file with instructions on building a demo program, which uses SDL to decode a file and render it to a . You can look how the demo is set up in CMakeLists.txt and modify it to your liking so that the encoder is exported from the library instead of the decoder.

Preferably though, you would create your own CMake project that imports the encoder library and exports the functions you would like to be callable from JavaScript code. Assuming you put the library in the libwebp/ subdirectory, create a CMakeLists.txt with something like this:

One approach is to define and await a Module.ready Promise. This is injected during Emscripten compilation using the --post-js flag. (see full examples)

Since you're missing a whole lot of information, let me just point out what I personally need to know in-order to cover bases.

1. How are you loading the .wasm module? Are you using pure vanilla js with an index.html? Or using something like reactjs or nextjs to load? Webpack has specific options now for loading .wasm modules.

2. What flags/options are you using to compile the module? Could you share the whole CLI command to compile?

3. In terms of intellisense, the IDE sounds like the definite issue. I'm using vscode with CMakeLists.txt for emscripten and I don't have any issue with intellisense on that part. If that's your toolkit, I am writing a blog on how to set it up.

If you're using vanilla js and serving with some sort of static server like python3 -m http.server, this particular commit has a working 2-classes-example folder which worked for me. WASM is loaded asynchronously so it needs to be called once it's loaded. Just follow the example and it should just work (fingers crossed).

If you're using webpack with something like ReactJS, make sure you use these flags when compiling:

This issue was resolved after installing the Microsoft Visual 2022 - Preview Version 17.1.0