Attack Roll
Iggynous
Member Posts: 4
FYI: I'm playing BG2ee on iPad, v1.2.
I've been playing bg and bg2 for a while; but only recently decided to delve into the mechanics. So far, I've just been going along with the formula that low THAC0 is good, low AC is good, and lotsa damage is good; but I want to gain a better understanding.
Which brings me to the components of attack rolls. This is an expression a "to hit" roll:
A + B = C
Could someone please educate me on what A, B & C are?
I've done some internet surfing and "supposedly": A is the random roll, B is the inverse AC of the target, and C is the result that the attacker's THAC0 must be equal or greater than for a hit to be scored.
HOWEVER
I did a little experiment with two of my characters. I stripped each of all weapons and armour and then had them slug it out, and watched their attack rolls. What I saw did not match the supposed definition of the equation above.
Character X (THAC0 9, AC 5) attacks Character Y (THAC0 17, AC 6). Here are 3 example rolls:
8 + 5 = 13: HIT
3 + 5 = 8: HIT
2 + 5 = 7: MISS
and when Character Y attacks Character X:
12 + 0 = 12: HIT
18 + 0 = 18: HIT
6 + 0 = 6: MISS
I'm happy that A = the random d20 roll, but in neither case was B = the inverse AC of the target or C = the result that the attacker's THAC0 must be equal or greater than for a hit to be scored.
So what's going on?
I've been playing bg and bg2 for a while; but only recently decided to delve into the mechanics. So far, I've just been going along with the formula that low THAC0 is good, low AC is good, and lotsa damage is good; but I want to gain a better understanding.
Which brings me to the components of attack rolls. This is an expression a "to hit" roll:
A + B = C
Could someone please educate me on what A, B & C are?
I've done some internet surfing and "supposedly": A is the random roll, B is the inverse AC of the target, and C is the result that the attacker's THAC0 must be equal or greater than for a hit to be scored.
HOWEVER
I did a little experiment with two of my characters. I stripped each of all weapons and armour and then had them slug it out, and watched their attack rolls. What I saw did not match the supposed definition of the equation above.
Character X (THAC0 9, AC 5) attacks Character Y (THAC0 17, AC 6). Here are 3 example rolls:
8 + 5 = 13: HIT
3 + 5 = 8: HIT
2 + 5 = 7: MISS
and when Character Y attacks Character X:
12 + 0 = 12: HIT
18 + 0 = 18: HIT
6 + 0 = 6: MISS
I'm happy that A = the random d20 roll, but in neither case was B = the inverse AC of the target or C = the result that the attacker's THAC0 must be equal or greater than for a hit to be scored.
So what's going on?
0
Comments
What's going on here is that you're equating B and C with the wrong items. Let's assume A = attack roll, but B is not the inverse of the Target's AC, nor is C what you think it is, and we'll add D.
B = miscellaneous attack modifiers (note these could be negative as well)
C = THAC0
D = Target's AC
Remember that THAC0 stands for "To Hit AC 0", so if the target has an AC greater than 0, that means he/she is easier to hit and this number will be subtracted from THAC0.
And the equation should instead be:
A (roll) + B (modifiers) ≥ (C (Attacker's THAC0) - D (Target's AC))
So if we break down your results:
For group 1: With a THAC0 of 9 and a target AC of 6, the number to beat is 3
(8) + (0) ≥ (9-6) : Hit
(3) + (0) ≥ (9-6) : Hit
(2) + (0) ≤ (9-6) : Miss
I took out the (+5) because it seemed you were putting in one of the AC numbers here. If this is not true, then there is a problem with the third equation.
The second set works out perfectly
(12) + (0) ≥ (17-5) : Hit
(18) + (0) ≥ (17-5) : Hit
(6) + (0) ≤ (17-5) : Miss
To go even further, not using your examples, if an enemy has a NEGATIVE AC, the game appears to add the inverse to produce the number to beat (due to the subtraction of a negative, which is the adding of a positive). So your first character has a THAC0 of 9, and the target has an AC of -3, the number that he must beat with his roll and any modifiers is (9 - (-3)) or 12.
Hope that helps!
So basically, what is displayed in the dialogue window when "to hit" rolls is enabled is just: Attack Roll + Modifiers = X, where "X" is the number that must be greater than or equal to your THAC0 for there to be a hit.
...the only problem is the examples I gave were copied from the dialogue window; so those 5s were put there by the game engine, not me. So the "miss" roll in my example where X attacked Y still doesn't make sense to me?
Figuring out the target number (THAC0 - AC) and then rolling to reach that number (with any bonuses or negatives) is quite literally how 1st and 2nd Ed. AD&D has done its attack model ever since I started playing it back in the 80s.
There are only two scenarios that pop off the top of my head (and please don't take offense):
1) You copied those numbers down wrong
or
2) The "To-Hit" roll is being displayed incorrectly.
Maybe someone else has some insight? I'm stumped! It probably doesn't help I've been up all night
The character with a 9 THAC0 - is that the BASE THAC0 or the final result? I -think- the base THAC0 might be 14 and final THAC0 is 9.
If I'm correct, what's happening is that game engine is basing its target number off of the Base THAC0 - Target AC, and then adding whatever modifiers you have to the dice roll. What this means is this:
Roll is 3 + 5 = 8 (your final roll)
Target number is 14 (Base THAC0) - 6 = 8 : Thus, hit
Next Roll is 2 + 5 = 7 : Thus, a miss.
I guess strength THAC0 modifiers aren't considered when unarmed?