Qt Quick 3D provides a high-level API for creating 3D content and 3D user interfaces based on Qt Quick. Rather than using an external engine, which creates syncing issues and additional layers of abstraction, Qt Quick 3D provides extensions to the existing Qt Quick Scene Graph for spatial content and a renderer for that extended scene graph. When using the spatial scene graph, it's possible to mix Qt Quick 2D content with 3D content.
Qt Quick 3D Documentation: