Question spell use TRUE or FALSE

Im working on a spell that will have a message to caster, one for victim and one for room

But Im unsure when to use TRUE or FALSE

also when to add ch or victim

Here is my examble:

  act("You hit...!", TRUE or FALSE, ch, 0, 0, TO_CHAR);
  act("$n hits you!", TRUE or FALSE, ch, 0, victim, TO_VICT);
  act("$N is hit.", TRUE or FALSE, victim, 0, 0, TO_ROOM);


Hope someone can help me ?

It is supposed to not display a message to a character who can't see through invisibility or for other reasons.  If it is false then it should show everyone the message.

char * act(const char *str, int hide_invisible, struct char_data *ch, struct obj_data *obj, void *vict_obj, int type);

So if I use true then they can see without detect invis and False they have to have detect invis ?

Yes, in theory, but it also covers imm invisibility which the potions wouldn't work on.  You'll still want to test to make sure it works as intended though

#define CAN_SEE(sub, obj) (SELF(sub, obj) || \
  ((GET_REAL_LEVEL(sub) >= (IS_NPC(obj) ? 0 : GET_INVIS_LEV(obj))) && \
  IMM_CAN_SEE(sub, obj)))

Im still confused what to choose for my spell messages haha

The act() documentation says: hide_invisible: A TRUE or FALSE value indicating whether or not to hide the entire output from any characters that cannot see the “performing character”

All the fight.c attacks use FALSE, so I would suggest copying that unless it isn't performing how you want it to.  If you are in combat, then you'll probably be knocked visible unless you are an imm (it says an immortal instead of the name) - You'd need to test to make sure.  

from fight.c:
  /* damage message to onlookers */
  buf = replace_string(dam_weapons[msgnum].to_room,
          attack_hit_text[w_type].singular, attack_hit_text[w_type].plural);
  act(buf, FALSE, ch, NULL, victim, TO_NOTVICT);