Hi,

I know c_trace instruction is used for that. The problem is that c_trace always returns positive number even if there are no obstacles between the player and the enemy, so how come I know if the enemy can see the player?

code?

Don't use the distance but the
if(trace_hit) ...
variable (or the hit macro, manual: hit and c_trace obviously).
Obviously you want to either c_ignore both player and enemy (or IGNORE_ME and IGNORE_PASSABLE and let's say set the player to passable immediately before the trace and reset the flag after).