Ability Modifier equation for Basic Fantasy

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GrimlinJoe
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Ability Modifier equation for Basic Fantasy

Post by GrimlinJoe »

I am working on making an ability score calculator using excel and I am having trouble finding the mathematic equation for how Basic Fantasy calculates its ability modifiers.

I know that for 5e it is (STAT-10)/2 making 18=+4 and 1=-5.

Hopefully this makes sense
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Dimirag
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Re: Ability Modifier equation for Basic Fantasy

Post by Dimirag »

While d20 and above used a formulaic method, BF (and its targeted games) does not uses a formula, instead uses a bell progression: 1, 2, 3, 4, 3, 2, 1.
Sorry for any misspelling or writing error, I am not a native English speaker
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GrimlinJoe
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Re: Ability Modifier equation for Basic Fantasy

Post by GrimlinJoe »

Ok figured it out

=ROUNDDOWN((STAT-10.5)/2.3,0)
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Solomoriah
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Re: Ability Modifier equation for Basic Fantasy

Post by Solomoriah »

You should know that the table was not created using a formula at all; conventionally (but not officially) numbers above 18 advance at a +1 per point basis, i.e. +4 at 19, +5 at 20, and so on. They are assigned where we wanted them, in keeping with tradition.

It's basically dumb luck that your formula works.
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Dimirag
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Re: Ability Modifier equation for Basic Fantasy

Post by Dimirag »

Solomoriah wrote: Wed May 12, 2021 9:29 am It's basically dumb luck that your formula works.
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Sorry for any misspelling or writing error, I am not a native English speaker
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GrimlinJoe
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Re: Ability Modifier equation for Basic Fantasy

Post by GrimlinJoe »

Solomoriah wrote: Wed May 12, 2021 9:29 am You should know that the table was not created using a formula at all; conventionally (but not officially) numbers above 18 advance at a +1 per point basis, i.e. +4 at 19, +5 at 20, and so on. They are assigned where we wanted them, in keeping with tradition.

It's basically dumb luck that your formula works.
It is very funny you say that. It did take me awhile to get it figured out but I made it work. I managed to create an excel tool to randomly generate a character that follows class and race restrictions. This will make generating NPCs so much easier for my campaigns
Seven
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Re: Ability Modifier equation for Basic Fantasy

Post by Seven »

Unless the progression is completely random, it's always possible and usually trivial to derive an equation for it. Anyone else did cubic spline interpolation in undergrads?
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billiambabble
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Re: Ability Modifier equation for Basic Fantasy

Post by billiambabble »

I was just about to say what Seven said (well, simpler, I guess). :) If there's a regular pattern in any table or matrix, there's usually a way to compress it into a formula or function. If the pattern doesn't quite fit then maybe some fudging is required. The beauty is creating really simple formulae. ;) It might have been that in the game BF is based on, the path to the least arguments with players was in creating aesthetically pleasing balanced bonuses and negatives (unlike the earliest edition, where the charts are asymmetric, which would possibly be harder to formularise in simple terms).
GrimlinJoe
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Re: Ability Modifier equation for Basic Fantasy

Post by GrimlinJoe »

My plan was to make an excel tool to generate an NPC or PC based on the class requirements and race restrictions and once it generates it also imports the modifiers based on the ability scores. I managed to make it work but after a long week of formatting and learning the syntax for excel it was definitely a headache but boy am I happy that I made it.

Based on RNG it will select what race and class based on the ability scores and automatically generate a PC/NPC with stats appropriate for its class and race
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