Collision Calculating and Loading

[TJ-OVERSITE]

I’ve set up a third-person walkabout using the plugin, but I’m encountering collisions with iModels that aren’t visible in the 4D view.
It appears that collision data is loaded at startup, which then blocks the actor’s movement even when those models are not currently shown.
How and when are collisions generated for Cesium tiles? Is there a way to manage them or force a refresh when the schedule changes?

[GhisBntly]

Hello,
For performance reason, the geometries are not modified when the 4D schedule leads Elements to be hidden. This is because Elements do not have each their own mesh component, which would be intractable for the render engine in large iModels. Also, cutting the geometries for growth simulation would be even more taxing for the resources.
Instead, the hidden triangles are simply made invisible by custom shading code in the material. This is indeed a problem for all types of intersections, like line traces for selection, and collisions: you will therefore need to disable collisions on the Pawn actor (in C++ it looks like GetWorld()->GetFirstPlayerController()->GetPawn()->SetActorEnableCollision(false);).

We have a "walk" mode in our own application though, which obviously requires some collisions. I will ask the team how it is handled with respect to the schedule visibility and other Element visibillity settings.

[GhisBntly]

I can confirm that the collisions also occur with invisible geometries with our own Walk mode. Fixing this requires code changes in the Unreal Engine itself, like we did for Element picking through hidden or cut-out objects in iTwin Engage, which is not currently planned. Editing the actual geometries could also be possible for fully hidden objects (at a cost), but hardly seems feasible for growth simulation, because the way the clipping plane needs to move smoothly with the schedule time.