Portal
Crossing
In portal engines, detect when the viewer change the current sector, is a problem. If the sectors are simple boxes, aligned with universe plans, it is easy. But the scenery design would be very limited. The implementation use the distance between viewer and the portal plan. If the viewer is collidin and the distance is negative, the portal is crossed. 3DFC v0.0.1 just test if viewer distance is negative between portal plan. Because this, is impossible design portals sharing the same plan. Other two problems remain with no solution on 3DFC v0.0.1. What to make when a visible object is between two sectors. When the viewer is clossing a portal and the portal is clipped by the near Z plan.