QRayCaster initialization on first frame

[alban774]

Greetings,

I would like to report a suspect behavior from the QRayCaster: It seems to work if and only if the QRayCaster is trigger before the first frame. Follows a complete test, that has to be repeated with and without the commented line.

A work around is to create a new QRayCaster instance whenever a shot is needed.

A fix may be to set RayCastingJob::m_castersDirty to true in the QRayCaster::trigger() method.

Qt3DCore::QEntity* sceneSphereMesh()
{
    auto rootEntity = new Qt3DCore::QEntity;
    auto sphereEntity = new Qt3DCore::QEntity(rootEntity);
    auto sphereMesh = new Qt3DExtras::QSphereMesh;
    sphereMesh->setRadius(10);
    sphereMesh->setRings(50);
    sphereMesh->setSlices(100);

    auto sphereMaterial = new Qt3DExtras::QPhongMaterial;
    sphereEntity->addComponent(sphereMesh);
    sphereEntity->addComponent(sphereMaterial);

    auto trnsf = new Qt3DCore::QTransform;
    trnsf->setTranslation(QVector3D(0, 5, 10));
    sphereEntity->addComponent(trnsf);

    return rootEntity;
}


int main(int argc, char** argv)
{
    QApplication app(argc, argv);
    Qt3DExtras::Qt3DWindow view;

    auto scene = sceneSphereMesh();
    view.setRootEntity(scene);
    view.camera()->setPosition(QVector3D(0, 0, 200));
    view.camera()->setViewCenter(QVector3D(0, 0, 0));

    auto pickableLayer = new Qt3DRender::QLayer;
    pickableLayer->setRecursive(true);
    scene->addComponent(pickableLayer);

    auto rayCaster = new Qt3DRender::QRayCaster;
    rayCaster->setRunMode(Qt3DRender::QAbstractRayCaster::SingleShot);
    rayCaster->setOrigin(view.camera()->position());
    rayCaster->setDirection(view.camera()->viewVector());
    rayCaster->setLength(300);
    rayCaster->addLayer(pickableLayer);
    scene->addComponent(rayCaster);

    view.renderSettings()->pickingSettings()->setPickMethod(
        Qt3DRender::QPickingSettings::TrianglePicking);
    view.renderSettings()->pickingSettings()->setPickResultMode(
        Qt3DRender::QPickingSettings::NearestPick);

    QObject::connect(rayCaster,
                     &Qt3DRender::QAbstractRayCaster::hitsChanged,
                     [](const Qt3DRender::QAbstractRayCaster::Hits& hits) {
                         qDebug() << "hits number: " << hits.size();
                     });

    // Uncomment to get hit results
    //  rayCaster->trigger();

    QTimer::singleShot(1000, [rayCaster]() {
        qDebug() << "timeout";
        rayCaster->trigger();
    });

    view.show();
    return app.exec();
}