ANGLE temp_ang;
VECTOR temp_vec;
vec_set(temp_vec, entity_you_want_check.x);
vec_sub(temp_vec, player.x);
vec_to_angle(temp_ang, temp_vec);
if((player.pan > temp_ang.pan - 5)&&(player.pan < temp_ang.pan + 5)) //play with 5
{ //your code }

VECTOR temp;
vec_set(temp, vector(player.x,player.y,player+200); //above the player's head
c_scan(temp, nullvector, vector(360,0,100), /*you have to look for the modes yourself*/);
if(you != NULL)
{
your code
}

if (NULL != vec_to_screen(entity_to_be_seen.x,camera)) // if the entity is inside the camera frustum 
{
	if(c_trace(player.x,entity_to_be_seen.x,IGNORE_ME) == 0) //and if there is no obstacle between player and entity
	{
		//do something();
	}
}

if(vec_to_screen(entity_to_be_seen.x,camera)) // if the entity is inside the camera frustum 
{
	if(c_trace(player.x,entity_to_be_seen.x,IGNORE_ME) == 0) //and if there is no obstacle between player and entity
	{
		//do something();
	}
}

var temp2[3];
vec_set(temp,my.x);
vec_sub(temp, player.x);
vec_to_angle(temp2, temp);

if(vec_dist (player.x, my.x) < 200 && abs(temp2.y - 90) < 10 ) //play with 10
{
	//my is above player in distance less than 200
}

E entity
< player walk left
> player walk right
        
          E
                  
  >              <
-------------------- // player_look_at_entity = 1;


          E

  <              >
-------------------- // player_look_at_entity = 0;

function scan_your_entity(){
	c_scan(player.x, player.pan, vector(100, 600, 300), ignore_me);
}

on_ctrl = scan_your_entity;


function skener() 
{
  if (event_type == EVENT_SCAN) 
  {
    you_see_entity = 1;
  }
}

action your_entity{
	static_entity=me;
	my.ENABLE_SCAN = ON; 
	my.event = skener;
}