leaningtech/cheerp

Hello!
I'm playing around with cheerp and I'm trying to understand what's the best way to push data out of wasm into the browser.
Here's a simple case of updating an array of positions, where a call to the native updatePositions_fromJS takes care of updating the local variable latestPositions with data calculated in wasm-land.

I wasn't able to get any other combination of flags / attributes working.

Have I gone off the mark, or is this the expected way of structuring such an intention?

index.html:

<script>
    let latestPositions;
    function updatePositions(positions) {
        latestPositions = positions;
    }
</script>
<script defer src="tessy.js"></script>
<script>
  Tessy.promise.then(function () {
    const tessy = new Tessy();

    function updateTessy(){
        tessy.updatePositions_fromJS();
        for (let index = 0; index < latestPositions.length; index++) {
            const component = latestPositions[index];
            // do something with component
        }
        //   call this many times
        setTimeout(() => {
            updateTessy()
        }, 1000 / 60);  
      }
    updateTessy()
  });

</script>

main.cpp:

#include <cheerp/clientlib.h>
#include <cheerp/client.h>

int nbPoints = 100;
int nbPointsStorage = nbPoints * 3;
float *positionsNative = new float[nbPointsStorage];

namespace [[cheerp::genericjs]] client
{
    void updatePositions(client::Float32Array *positions);
}

void [[cheerp::genericjs]] updatePositions_fromGeneric(float *t, int size)
{
    client::Float32Array *positions = cheerp::MakeTypedArray(t, sizeof(float) * size);
    client::updatePositions(positions);
}

void updatePositions()
{
    delete[] positionsNative;
    positionsNative = new float[nbPointsStorage];
    for (int i = 0; i < nbPoints; ++i)
    {
        positionsNative[i] = i;
    }
    updatePositions_fromGeneric(positionsNative, nbPointsStorage) ;
}

class [[cheerp::genericjs]] [[cheerp::jsexport]] Tessy
{
public:
    Tessy(){}

    void updatePositions_fromJS()
    {
        updatePositions();
    }
};

void webMain()
{}

And this is how I built this:

clang++.exe -target cheerp-wasm main.o -o tessy.js -c src/main.cpp