How to retrieve java class from jna reference pointer

Question

I am porting the openvr sample to jogl, after we created the binding with jna.

Almost at the end (before rendering the controllers and the tracking base stations), I got stuck trying to retrieving the model class in java from a reference pointer in C++.

C++ code here:

while ( 1 )
{
    error = vr::VRRenderModels()->LoadRenderModel_Async( pchRenderModelName, &pModel );
    if ( error != vr::VRRenderModelError_Loading )
        break;

    ThreadSleep( 1 );
}

LoadRenderModel_Async here:

/** Loads and returns a render model for use in the application. pchRenderModelName should be a render model name
* from the Prop_RenderModelName_String property or an absolute path name to a render model on disk. 
*
* The resulting render model is valid until VR_Shutdown() is called or until FreeRenderModel() is called. When the 
* application is finished with the render model it should call FreeRenderModel() to free the memory associated
* with the model.
*
* The method returns VRRenderModelError_Loading while the render model is still being loaded.
* The method returns VRRenderModelError_None once loaded successfully, otherwise will return an error. */
virtual EVRRenderModelError LoadRenderModel_Async( const char *pchRenderModelName, RenderModel_t **ppRenderModel ) = 0;

jna translated it as (here):

public interface LoadRenderModel_Async_callback extends Callback {

    int apply(Pointer pchRenderModelName, PointerByReference ppRenderModel);
};

On java I am trying to load the model in this way (here):

int error;
PointerByReference modelPtrRef = new PointerByReference();

while (true) {

    Pointer stringPointer = new Memory(modelName.length());

    error = renderModels.LoadRenderModel_Async.apply(stringPointer, modelPtrRef);

    if (error != VR.EVRRenderModelError.VRRenderModelError_Loading) {
        break;
    }

    try {
        Thread.sleep(1);
    } catch (InterruptedException ex) {
        Logger.getLogger(ModelsRender.class.getName()).log(Level.SEVERE, null, ex);
    }
}

RenderModel_t m = new RenderModel_t(modelPtrRef.getValue());
m.read();

But m is empty, that is vertexData is null and vertexCount is 0, on c++ I have valid values instead..

How shall I retrieve the java class from a reference pointer in c++?

Answer 1

Here's something a little simpler:

if (errorBuffer.get(0) != VR.EVRRenderModelError.VRRenderModelError_None) {
    return null;
}

int error;
PointerByReference pref = new PointerByReference();

while (true) {

    error = renderModels.LoadRenderModel_Async.apply(modelName, pref);

    if (error != VR.EVRRenderModelError.VRRenderModelError_Loading) {
        break;
    }

    try {
        Thread.sleep(1);
    } catch (InterruptedException ex) {
        Logger.getLogger(ModelsRender.class.getName()).log(Level.SEVERE, null, ex);
    }
}
RenderModel_t model = new RenderModel_t(pref.getValue());


public class RenderModel_t {
    public RenderModel_t(Pointer p) {
        super(p);
        read();
    }
}