Returns whether the target/given entity is visible from the this entity.

This is meant to be used only with NPCs.

Differences from a simple trace include:

• If target has FL_NOTARGET, returns false
• If ai_ignoreplayers is turned on and target is a player, returns false
• Reacts to ai_LOS_mode:
• • If 1, does a simple trace with COLLISION_GROUP_NONE and MASK_BLOCKLOS
• • If not, does a trace with MASK_BLOCKLOS_AND_NPCS (- CONTENTS_BLOCKLOS is target is player) and a custom LOS filter (CTraceFilterLOS)
• Returns true if hits a vehicle the target is driving