Basic Attack Speed Formula

[Iainuki]

Since the advent of weapon calculators, I've had increasing difficulty finding basic information about how to calculate attack speeds. To be clear at the outset, I don't want a link to a calculator, I want to know how the calculators work.

I'd like an equation that, when I plug in the weapon speed, equipment IAS, skill IAS, and the base number of animation frames for a particular weapon type, returns the the number of frames an attack with that weapon will require. I've seen the formula 120*IAS(120+IAS) - WS + SIAS, but without knowing exactly how the effective IAS so calculated modifies the frames, I don't see how to use it. Also, are the tables of the base frames by class and weapon type still up on the web somewhere?

If such a thing doesn't exist, how do the calculators work? A massive look-up table? If so, is there anywhere I can just access the look-up table directly without having to repeatedly vary the parameters in a calculator?

[Taem]

It's a formula Jarluf figured out light-years ago. I have it on a custom made calculator I made with excel, but it's archived. Give me awhile to find it.

[Taem]

It's a formula Jarluf figured out light-years ago. I have it on a custom made calculator I made with excel, but it's archived. Give me awhile to find it.

WHAT YOU NEED TO KNOW
SIAS = Skill Based "Increased Attack Speed"
IAS = Item based "Increased Attack Speed"
WBase = Base Weapon Attack Speed
NOTE: You can find each items WBas on the Arreat Summit; this is NOT any IAS on the weapon itself!
Base = The Base Weapon speed for that particular weapon in conjunction with your class
NOTE: Each class has different frames with the same weapon, thus a double-bow could be 11 fps on a amazon, and 16 fps on a sorceress. I'm not sure where to find this information anymore

FORMULA
NOTE: You will need to figure out your EIAS and Frames using the following formula:

EIAS = WBase+ SIAS + [IAS/(1 + IAS/120)]
FPS = {256*(Base + 1)/[(100 + EIAS)/100*256]} - 1



I hope you find that information useful. Here are my Excel spreed sheet formula if you want:

EIAS
=A2+A4+ROUNDDOWN((A6/(1+A6/120)),0)

A2 = Base Attack Speed
A4 = SIAS
A6 = Item Based IAS

Frames
=ROUNDUP(256*(A8+1)/ROUNDDOWN((100+B2)/100*256,0),0)-1

A8 = Base Weapon Speed

[Taem]

P.S. If I'm not mistaken, Zeal, Fury, and Fend use a different or modified formula than the one listed above.

[Iainuki]

Base = The Base Weapon speed for that particular weapon in conjunction with your class
NOTE: Each class has different frames with the same weapon, thus a double-bow could be 11 fps on a amazon, and 16 fps on a sorceress. I'm not sure where to find this information anymore

Thanks! I had the EIAS component, but not how to calculate frames from the base frames. This was very helpful!

IIRC, the formula for Fury/Fend/Zeal is fairly simple, something like 1/2 times the normal frames for the attacks after the first, with conditions on how you round. If anyone knows it for certain, that would be helpful too.

Does anyone have the tables of basic frames? While these aren't too much of a pain to extract from the calculators, it would be nice not to have to. Does the table live in the data files somewhere?

[librarian]

Heiho,

not sure if this one will help you a lot, I've derived the main part from some posting Myrdinn did quite a while ago
http://www.mannm.org/d2library/faqtoids/ias_eng.html
links to board threads about rollback attacks like Zeal are included, hopefully they're still valid

extraction of AnimData.d2
http://www.mannm.org/d2library/faqtoids/animspeed.html
it's a very huge file, and the extract is still big.

[Iainuki]

not sure if this one will help you a lot, I've derived the main part from some posting Myrdinn did quite a while ago
links to board threads about rollback attacks like Zeal are included, hopefully they're still valid

extraction of AnimData.d2 it's a very huge file, and the extract is still big.

It took me awhile to figure them out, but those are useful, thanks:).