Rendering Improvements, Fixes + Occlusion Culling

[AzureAaron]

Occlusion Culling

• Implemented an occlusion culling system
  • With Frustum Culling, objects that are in the camera's FOV won't be culled even if they're blocked by walls or other surfaces while with occlusion culling, if the view to an object is blocked then it is culled.
  • The implementation first checks if the bounding box is within the frustum, if its not then the function short-circuits to avoid unnecessary path tracing. If it is within the frustum then the rest of the occlusion culling logic is executed.
• Uses the Occlusion Culling library made by Logistics Craft

Rendering Fixes/Changes

• All RenderHelper methods now use some kind culling
  • The renderFilledIfVisible method now uses occlusion culling
    • Fixes being able to see the mirrorverse waypoints from the edge of the Stillgore Château
  • The rest of the methods now use frustum culling since they render things through walls (thus being able to be seen as long as they're in the camera's FOV)
• The beacon beams are now rendered directly after their vertices have been written to the buffer
  • Fixes an issue where they could render incorrectly (e.g. flickering, weird rotations)
  • Also simplified the logic in the method to be more readable
• The beacon beams now render at a maximum height of 319 to match the world build height limit
  • Prevents a weird discolouration issue with them at higher Y levels
• Made some RenderHelper methods private so that culling checks aren't accidentally skipped
• The pointExistsInArea method now uses the unboxed version of boolean