This post covers what twitching is, testing results of THF twitch attack speeds, and its testing history. A future one will cover when it is better to twitch as opposed to the standard standing still and attacking (or, "auto-attacking").
Twitching description
In DDO, twitching refers to interrupting your attack animation by alternating between moving and standing still when you're attacking. The reason is that the later standing attack animations are slower, and so interrupting the animation sequence by moving will reset your attack animation to an earlier, faster one, thereby increasing your overall attack rate (and hence possibly increasing your DPS). It is generally used for two-handed fighting (THF), but can also occasionally be used for other circumstances, such as unarmed without monk levels (because the kick animation is absurdly slow). Note that although your attack speed is increased, you will also receive -4 to-hit on half of the attacks due to moving.
First, let's look at how the attack animations work. When standing, there are four attack animations that are used sequentially: a baseball swing from right to left (1st), a vertical downward swing (2nd), a vertical upward swing (3rd), and a left to right swing (4th). When moving, there are two attack animations: an upper right to lower left swing (1st), and a lower left to upper right swing (2nd). Which animation follows which is shown in the diagram below:
So for example, if you started moving at the end of the 3rd standing animation, you would next do the 1st moving animation. If you stopped moving at the end of the 2nd moving animation, you would then do the 3rd standing animation. And so forth. From the above diagram, you can see the various possible attack animation loops that the game can cycle through.
For the standard THF standing attack animation, unbuffed, the durations of each attack are roughly as follows:
Code:
attack duration (seconds)
1st 0.621
2nd 0.410
3rd 0.938
4th 0.804
average 0.693
The times are based on when the attack's result (i.e. hit, miss, etc.) show up in the combat log. As you can see, the 2nd THF attack animation (a vertical downward strike) has a fast cooldown -- you can do a new attack very quickly after it completes. You can also see that the latter two attack animations are relatively slow. The average duration is around 0.693 seconds, which works out to around 86.6 swing animations per minute.
Twitching relies on using the attack animation loop highlighted red in the above diagram. Rather than cycling through all the standing animations, you move before the end of the 2nd standing attack animation. This makes you do the 1st moving animation, during which you stop moving, and thus returning to the 2nd standing animation. The 1st moving animation is actually not that fast -- around 0.764 seconds -- but the average duration of this loop, the 2nd standing animation + the 1st moving animation, is 0.587 seconds, which then works out to (in this case) 102.2 swing (attack) animations per minute, which is around 18% more animations than if you were just standing still. Because you are effectively having more swings per minute, you are therefore also potentially increasing your DPS.
Twitch testing results
To test twitching swing animation speeds, I basically backed up into a tavern table at the appropriate time. In the videos, it will look like I'm not moving, but actually, the character is trying to move backwards into the table at the end of the 2nd standing animation. Otherwise, the procedure matches that given in the original post. The results of the tests, in SPM (swing animations per minute, or attack animations per minute), are:
Code:
fTwitch -- greataxe
boost 0% 10% 15% 20% 25% 30% 35% 40% 45%
none 99.4 118.0 124.9 131.9 137.9
collar 112.1 131.1 137.1 143.2 150.8
haste 119.3 137.7 143.2 150.9 156.5
average 99.4 112.1 118.7 124.9 131.5 137.6 143.2 150.8 156.5
sTwitch -- greatsword
boost 0% 10% 15% 20% 25% 30% 35% 40% 45%
none 102.4 119.7 125.3 131.5 137.1
collar 113.3 131.1 137.3 142.0 149.1
haste 119.6 136.5 142.4 148.3 154.2
average 102.4 113.3 119.7 125.3 131.3 137.0 142.2 148.7 154.2
Note that the greataxe counts as a "fast THF" weapon, while the greatsword counts as a "slow THF" weapon, and hence "fTwitch" and "sTwitch" respectively. As usual, the linear regression formula that best matches this data is in the original post, and the videos that this testing was based on is in the second post.
The most interesting thing about these test results is that they differ significantly from previous work on attack speeds. Given a 15% attack speed modifier from the haste spell, the following are the estimated attack speeds given by cforce's attack speed estimator for various levels of haste boost:
Code:
Boost% fTwitch sTwitch Unarmed TWF fastTHF slowTHF
0% 128.4 128.4 115.5 105.5 102.1 102.1
15% 146.6 146.6 132.2 119.5 112.5 112.5
20% 153.9 153.9 139.0 125.0 116.4 116.4
25% 161.9 161.9 146.4 131.1 120.7 120.7
30% 170.8 170.8 154.7 137.8 125.3 125.3
while the following are the estimated attack speeds given by my linear regression formulae:
Code:
Boost% fTwitch sTwitch Unarmed TWF fastTHF slowTHF
0% 118.5 119.5 111.3 102.2 99.9 99.1
15% 137.6 136.9 129.4 117.8 113.3 111.6
20% 143.9 142.7 135.5 123.0 117.8 115.8
25% 150.3 148.4 141.5 128.1 122.2 119.9
30% 156.6 154.2 147.5 133.3 126.7 124.1
The difference, percentage-wise, is below:
Code:
Boost% fTwitch sTwitch Unarmed TWF fastTHF slowTHF
0% 8.29% 7.37% 3.71% 3.24% 2.18% 2.98%
15% 6.54% 7.09% 2.18% 1.49% -0.72% 0.78%
20% 6.90% 7.86% 2.60% 1.70% -1.12% 0.57%
25% 7.74% 9.08% 3.49% 2.31% -1.25% 0.63%
30% 9.07% 10.79% 4.89% 3.34% -1.13% 0.93%
As you can see, most of the results are fairly similar, differing by a few percent at most. However, the twitch swing animation speeds were reported as being significantly faster (on average, by around 8%) than what my testing results indicate. And if you doubt my results, I would recommend that you download the videos and count up the animations yourself -- that's why they're there.
Twitch testing history
The reason for this discrepancy has to do with how the data was originally collected. Unlike some of the other data, the twitch numbers weren't tested by cforce himself but based on a video by Shade, as you can read about in Monkey_Archer's attack speed thread, and in cforce's attack speed thread. However, Shade was using a capped barbarian for his video. Unfortunately, as I documented here and Monkey_Archer confirmed here, it turns out that barbarians were getting a hidden alacrity boost from their capstone. So Shade's attack speed was taken as a baseline speed for twitch, whereas in reality, it was benefiting from an alacrity bonus. Hence, the resulting estimated numbers were faster than the actual numbers.
For example, a pure fighter pre-update 5, with 20% from madstone, 30% from haste boost 4, and 10% from the fighter capstone, is estimated by my formula to have 136.6 SPM while not twitching, and 171.5 SPM while twitching, a 25.5% increase by twitching. By cforce's formula, however, the fighter would be estimated to have 136.3 SPM while not twitching, and 193.7 SPM while twitching, a 42.1% increase. Now looking at Durnak's pre-Update 5 capped fighter + epic SoS video here, taking a long stretch of standing animations (from frame 2986 to 3346 at 29.97 frames/second), he attacks at 139.0 SPM when standing still. When twitching however, such as from frame 2075 to 2116 or from frame 2170 to 2211, he attacks at 175.4 SPM, so by twitching, his attack speed increased by 26.2% -- thus matching my formula much more closely.
(1:10.603 - 1:09.235) / 4 attacks = 0.342 seconds per attack
60 seconds per minute / (0.342 seconds per attack) = 175.4 attacks per minute
In short, twitch has always been at the speed matching my formula above (or at least, since March 2010, so likely since Sept 2009 or so with Module 9, when they last did a major change to attack speed mechanics), just that the current DPS calcs have been using incorrect values for its animation speed and hence, the DPS output for this type of weapon style.
The remaining question then is when is it better to twitch, as opposed to just standing still and attacking (which I'll often shorten to "auto-attacking" since that's all you really have to do), but I guess I'll cover that in a future post, since I think this one is long enough already.