Implement NPC culling

[JaXt0r]

Currently all NPCs are loaded immediately and shown all the time. We need to implement proper culling for performance reasons.

Investigation

• Analyze the value from original G1 about the distance for culling --> ~10-15m (First mesh is made transparent, +5m, the NPC is despawned and respawned if reached)
• Implement an NPC culling manager similar to the Vob culling manager. (Maybe reuse it?)
• Handle G1 behaviour (please check with Marvin mode spawns and G1 checks for yourself):
  • It seems that culled out NPCs are still "working". It means for a certain distance their invisible but still doing their routines? - yes. ~+5m distance after invisibility, they will be removed from game.
  • It seems that if you're really far away, they will be completely being disabled and re-enabled when you're close by again.
• To be handled: Whenever an NPC is brought back again (e.g. Marvin mode in G1 spawning to a far away WP), the routine (e.g. for walking) is being interpolated between Routine-start and Routine-end. (You can check with the two swamp Templar walking between swamp and old mine. When you spawn next to them, they will immediately spawn at their interpolated routine route)

Implementation

• v1:
  • Spawn all NPCs+Monsters when world is loaded (and do not render them until you reach their spot)
  • Culling out of NPCs/Monsters after x-meters
  • When spot is reached again, make the meshes visible again
  • NPCs/Monsters just restart their routines from scratch
• v2:
  • Load SaveGame and NPCs/Monsters which are inside RootObjects, will go on with their current routine status and spawn points based on the information stored
• v3:
  • Optimize Culling spheres: If NPC is walking, then alter culling-array's value
  • Implement culling logic similar to G1: (1) fade out NPC/Monster, (2) destroy ~+5m further away
  • As Wld_InsertNpc() is called only once per new game start, we need to ensure, that our culling data stays the same across world switchings