Qt3D: Material and Frame Graph logic composition

[Igor Baidiuk]

Hello!

I'm now checking Qt3D's capabilities for rendering nontrivial 3D scenes as an alternative to OpenSceneGraph manual integration into QML. While Qt3D API looks elegant, it severely lacks documentation. In particular, both global frame graph and local material effects seem to overlap somehow in their responsibilities. Can someone please point to some proper description how material and frame graph trees are composed when certain entity is being rendered?

Thanks,
Igor

[kshegunov]

The documentation is a world of hurt, I hear you. Can't give you a resource, because I haven't found one, but from my investigations glancing through the source, I could give you the broad strokes.
The material is a component, it's basically nothing that's visual. When the frame graph is traversed it collects the jobs from the entities (i.e. from the components attached to the entities) and then runs them through the pipeline. So no, the effects and techniques are not duplicating the framegraph per se, they're just a specification(s) for the entity on how to be rendered (you can filter out specific techniques from the frame graph if you use deferred rendering for example).