@Cute3d, yes, it finally works. Idk what was wrong. Example project:https://github.com/Nonmant/Qt3DExtras-QText2DEntity-Example
And due to god-knows-what reasons it doesn't work in debug mode. Hope, that project can help someone.

OK, seems like shadow casting on the default light might be broken. Turning it on caused the scene to crash.

0_1535579011318_127c726b-5b85-4a50-b7fa-d07e02663dc9-image.png

Ok, solution 2 was simpler than i expected. I'll post my code below, in case someone else needs something similar. It flips a QEntity along the x-axis and the winding of the triangles. It only works with the primitive type QGeometryRenderer.Triangles.

Jan

void mirrorEntity(Qt3DCore::QEntity *entity) { for (QNode* node: entity->childNodes()) { if (QEntity* e = dynamic_cast<QEntity*>(node)) mirrorEntity(e); if (QGeometryRenderer* r = dynamic_cast<QGeometryRenderer*>(node)) mirrorGeometryRenderer(r); } } void mirrorGeometryRenderer(QGeometryRenderer *geometryRenderer) { QGeometry* geometry = geometryRenderer->geometry(); for (QAttribute* a : geometry->attributes()) { if (a->name() == QAttribute::defaultPositionAttributeName()) { QByteArray data = a->buffer()->data(); // flip along x-axis float *bufferContent = reinterpret_cast<float*>(data.data()); int chunkSize = a->byteStride()/sizeof(float); int positionOffset = a->byteOffset(); for (uint i=0; i<a->count()*chunkSize; i+=chunkSize) { int offsetI = i + positionOffset; bufferContent[offsetI] = -bufferContent[offsetI]; // invert x } // change winding const int size = a->byteStride(); char* tmp = new char[size]; for (int i=0; i<data.length(); i+=a->byteStride()*3) { memcpy(tmp, &data.data()[i+size], size); memcpy(&data.data()[i+size], &data.data()[i+size*2], size); memcpy(&data.data()[i+size*2], tmp, size); } delete[] tmp; a->buffer()->setData(data); break; } } }

I've got the same issue with Qt3DExtras::QText2DEntity. But I found the workaround.
Look like there is a bug? in implementation of Qt3DExtras::QText2DEntity that prevents internal initialization (QText2DEntityPrivate::setScene is never called). This happens when scene is already visible and Qt3DExtras::QText2DEntity is created with parent entity passed to constructor. The workaround I used to make it work is to pass nullptr (which is default) as parent in constructor and call ->setParent(parentEntity) in separate call.

m_text2dLabel = new Qt3DExtras::QText2DEntity(); m_text2dLabel->setParent(parentNode);

There has been a question here already: https://forum.qt.io/topic/85533/qt3d-qml-geometry-bounding-box. But I couldn't really find any code in the github repository.

What I'd suggest is you get the QGeometryRenderer from the text entity. The geometry renderer has a QGeomemtry attribute, which in turn has a set of QAttributes. There must be an attribute with a name like "vertexPosition". You need to get the QBuffer from the attribute and retrieve the vertices starting at position byteOffset (that is an attribute of QAttribute). The next vertexSize (also an attribute of QAttribute) entries should belong to the vertex position. Then continute at position byteOffset + i * byteStride, while i being the index you're reading right now. Do this for count (also an attribute) times. This way you can get all vertex positions and calculate a bounding box based on them.

@Lukadriel Hi, One year passed and still waiting for the proper example. Did they give any tips?

@Wieland I was afraid of that. Seems like a glaring omission. Oh well, I needed to download the sources anyway to peek at Scene3D. Thanks.

@jimfar Hi, I have the same problem in my Qt application... Any solutions?

Hi! There is an example with 4 cameras, see Multi Viewport QML Example. The example uses the QML API but porting it to C++ shouldn't be too hard.

Hello, how to solve this problem? Could you please tell me the answer, thanks in advance!

I have reported this issue on the Qt bug tracker.
If someone is interested: https://bugreports.qt.io/browse/QTBUG-60738

@chris2401
Hi I would guess on OpenGL 2.1 but could not find and doc either :)

@kshegunov I think you are right. By just putting the lightentity into the camera:

Qt3DCore::QEntity *lightEntity = new Qt3DCore::QEntity(basicCamera);

It seems to move dynamically. Now I have to set some other things but that might have to do just with how I want my objects to show :)

Hi! I wrote resolution like @AlanWasHere, but a little clearer

void addLine(QEntity *parentEntity, const QVector3D &srcPos, const QVector3D &targPos) { auto edgeEntity = new QEntity{parentEntity}; auto cylinder = new QCylinderMesh{edgeEntity}; auto len = srcPos.distanceToPoint(targPos); cylinder->setLength(len); cylinder->setRadius(0.1f); auto transPoint = targPos - srcPos; auto xAngle = atan(sqrt(pow(transPoint.z(), 2) + pow(transPoint.x(), 2)) / transPoint.y()) / M_PI * 180; auto yAngle = (transPoint.x() == 0 && transPoint.z() == 0) ? 0 : atan(transPoint.x() / transPoint.z()) / M_PI * 180; auto transform = new Qt3DCore::QTransform{edgeEntity}; transform->setRotationX(xAngle); transform->setRotationY(yAngle); transform->setTranslation((srcPos + targPos) / 2); auto material = new QPhongMaterial{edgeEntity}; material->setDiffuse("#ffff00"); edgeEntity->addComponent(cylinder); edgeEntity->addComponent(transform); edgeEntity->addComponent(material); }

For further reference this issue seems solved as described in this post.