[Help] AC, Thac0, Thac32 and "Chance to Hit" calculations.

Posted by Oblisgr on Sat 23 Apr 2016 11:05 AM — 2 posts, 14,243 views.

Oblisgr Sat 23 Apr 2016 11:05 AM #0

Hello,
I have played AD&D as player and DM so i can understand om basic point in battle calculation.

I can see that each mob/race has an AC, Thac0 and Thac32 stats. I can understand that the AC represends the way the mob will avoid the attck of the enemy. And the Thac0 the try the player has to put (in dice roll) to hit the mob. Actuall AD&D stuff.

Just a few questions:

1. The Thac32 does the same with as Thac0 just for AC=32?

2. The way the battle is calculated?

I imagine that the engine rolls a d20 at every attack and does thac0-roll to get the AC that can be hit like AD&D right?

I see in AreaEditor that a mob of level 1 has near 100 AC, and every level above has lower (like AD&D) and here i get confused. if AC=100 how the hell the attack chance is calculated. Because this way the AD&D formula will now work.

In AD&D level 1 mob without armor and bonus got AC=10 and not AC=100. So...?

If someone want to write me the actual SMAUG battle formula of "chance to hit", please do to help go further in understanding.

Thanks in advance

Nick Gammon Australia Forum Administrator Sun 24 Apr 2016 02:08 AM #1

I suggest you look at the source. I don't know for sure what the code does with them. I found this in fight.c:


   thac0 = interpolate( ch->level, thac0_00, thac0_32 ) - GET_HITROLL( ch );
   victim_ac = UMAX( -19, ( int )( GET_AC( victim ) / 10 ) );


...

   if( diceroll == 0 || ( diceroll != 19 && diceroll < thac0 - victim_ac ) )
   {
      /*
       * Miss. 
       */
      if( prof_gsn != -1 )
         learn_from_failure( ch, prof_gsn );
      damage( ch, victim, 0, dt );
      tail_chain(  );
      return rNONE;
   }