如何从jna引用指针检索java类

Question

在我们用jna创建了binding之后，我正在将openvr sample移植到jogl

几乎在结束之前（在渲染控制器和跟踪基站之前），我试图从C++中的引用指针检索java中的模型类。p>

C++代码here:

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

    ThreadSleep( 1 );
}

{}{a5}：

/** 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将其翻译为（here）：

public interface LoadRenderModel_Async_callback extends Callback {

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

在java上，我试图以这种方式加载模型（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();

<^ >但是^ {CD2>}是空的，即^ {< CD3>}是空的，^ {< CD4>}是0，C++上有有效的值代替…

<>如何从C++中的引用指针检索java类？

Answer 1

解决后，我需要创建一个指针modelPtr，然后创建一个指向指针modelPtrPtr的指针，并将其传递给LoadRenderModel_Async

最后，我通过将指针的值传递给指针和read()来实例化一个模型类，以从本机内存检索值到堆内存：

    RenderModel_t.ByReference modelPtr = new RenderModel_t.ByReference();

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

    int error;
    PointerByReference modelPtrPtr = new PointerByReference(modelPtr.getPointer());

    while (true) {

        Pointer stringPointer = new Memory(modelName.length() + 1);
        stringPointer.setString(0, modelName);

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

        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(modelPtrPtr.getValue());
    model.read();

Answer 2

这里有一点简单：

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();
    }
}