[Interest] [Qt3D] Mixing C++ and QML

[Jérôme Godbout]

You can create your own MyQmlEntity class and expose a method that call it:

class MyQMlEntity : public QEntity
{
  Q_OBJECT
  Q_PROPERTY(VariantList components READ get_components WRITE
set_components NOTIFY componentsChanged)

Q_INVOKABLE void add(QObject* obj) {
addComponent(dynamic_cast<QComponent*>(obj); }
Q_INVOKABLE void remove(QObject* obj)
{ removeComponent(dynamic_cast<QComponent*>(obj)); }
};

you can then read and write data into the underlaying QEntity (this is far
from optimal code, just quick example). You may have to wrap the QComponent
too. you could also make it easier to expose the components list from
QComponentVector to something Qml can handle.

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Jerome Godbout
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On Thu, Oct 19, 2017 at 11:40 AM, Xavier Bigand <flamaros.xavier at gmail.com>
wrote:

> The issue is that QEntity doesn't reflect directly the qml type Entity,
> this is the same for many Qt3D classes.
>
> Here is the declaration of QEntity from qentity.h
>
> class QT3DCORESHARED_EXPORT QEntity : public QNode
>
> {
>
>     Q_OBJECT
>
> public:
>
>     explicit QEntity(QNode *parent = nullptr);
>
>     virtual ~QEntity();
>
>
>     QComponentVector components() const;
>
>
>     void addComponent(QComponent *comp);
>
>     void removeComponent(QComponent *comp);
>
>
>     QEntity *parentEntity() const;
>
>
> protected:
>
>     explicit QEntity(QEntityPrivate &dd, QNode *parent = nullptr);
>
>
> private:
>
>     Q_DECLARE_PRIVATE(QEntity)
>
>
>     QNodeCreatedChangeBasePtr createNodeCreationChange() const Q_DECL_OVERRIDE;
>
> };
>
>
>
> As you can see the method addComponent is not virtual and exported as Q_PROPERTY, so when creating a derived class of QEntity when instanced in qml it doesn't inherited of Entity properties.
>
>
>
>
> 2017-10-19 15:44 GMT+02:00 Jason H <jhihn at gmx.com>:
>
>> > I am looking for a way to manage an Entity tree in C++ and the Scene
>> configuration in QML. My C++ code manage entities from a root node and I
>> want to move the Frame graph and camera management,... to qml.
>> > I can't figure out how to do that because if create a class that derive
>> from QEntity some properties of Entity aren't declared like "components".
>> >
>> > My goal is to have an object hierarchy made with QEntity in c++ and
>> dynamic views on it made in QML. Scene views should be dockable,...
>>
>>
>> This is well-documented. QEntity inherits from QObject so you are good.
>> I'm not sure what you mean by "like components". Public properties, signals
>> and slots are visible to QML. If not it's a simple matter of wrapping them
>> in a public one.
>>
>> http://doc.qt.io/qt-5/qtqml-cppintegration-topic.html
>>
>>
>>
>>
>
>
> --
> Xavier
>
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