Qt3D: Synchronize with frame rate?

Andreas E.

Hello,

is there a signal when Qt3D has finished rendering a frame or swaps the display buffers? What is the mechanism to synchronize animations with the actual frame rate?

Thanks in advance

wrosecrans

To get a per-frame callback, include QFrameAction and add one as a component to a node in your scene.

#include <QFrameAction>
#include <QEntity>
...
    Qt3DCore::QEntity *root;
...
    Qt3DLogic::QFrameAction *fa = new Qt3DLogic::QFrameAction;
    root->addComponent(fa);
    fa->connect( fa, SIGNAL(triggered(float)), &some_controller, SLOT(update()) );

And the root node's FrameAction component will trigger the single every frame. In practice, I think you can probably also get about the same effect by making a QTimer with zero timeout. After rendering a frame, the mainloop will be idle and trigger the idle timer. But it won't be guaranteed to be entirely in sync.