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Turret damage: Difference between revisions

From EVE University Wiki
m minor fixes, mostly rephrasings
m minor rewrites, improved examples, small layout changes
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{{Weapon Systems Links}}
{{Weapon Systems Links}}
==Hit chance==
==Hit chance==
A turrets chance to hit a target is calculated from several parameters. The resulting value is between 0 and 1, or 0% and 100% if you will.  
A turrets chance to hit a target is calculated from the equation below. It will produce a result between 0 and 1, or 0% and 100% if you will. This value is then compared to a random number to see if the turret hits or misses.
The hit chance of a turret is given by this formula


<math>\pagecolor{Black}\color{White}\text{Chance to Hit} = {0.5^{\left({\left({\frac{V_{angular} \times 40000m}{WAS \times sig_{target}}}\right)^{2} + \left({\frac{max(0, Distance - opt_{turret})}{fall_{turret}}}\right)^{2}}\right)}}</math>
<math>\pagecolor{Black}\color{White}\text{Chance to Hit} = {0.5^{\left({\left({\frac{V_{angular} \times 40000m}{WAS \times sig_{target}}}\right)^{2} + \left({\frac{max(0, Distance - opt_{turret})}{fall_{turret}}}\right)^{2}}\right)}}</math>
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fall<sub>turret</sub> is falloff of turret
fall<sub>turret</sub> is falloff of turret


Those who like math may recognize that the hit chance equation has the form ''x''<sup>(''a''+''b'')</sup>, which can also be written as ''x<sup>a</sup>x<sup>b</sup>''. In our case, x = 0.5, a = all tracking terms and b = all range terms. In other words, the hit chance equation can be thought of as having two separate parts, which are multiplied at the end to get the final hit chance. This means that tracking and range can be treated as two seperate things.
Those who like math may recognize that the hit chance equation has the form ''x''<sup>(''a''+''b'')</sup>, which can also be written as ''x<sup>a</sup>x<sup>b</sup>''. In this case, x = 0.5, a = all tracking terms and b = all range terms. In other words, the hit chance equation can be thought of as having two separate parts (tracking and range), which are calculated individually and then multiplied at the end to get the final hit chance. This means that tracking and range don't interfere with one another, they are indeed two seperate things.


One more thing we can learn from the equation is that the loss of hit chance due to falloff and due to tracking share the exact same behaviour, since they both look like ''0.5''<sup>(something / x)<sup>2</sup></sup>, where x is either tracking or falloff. So by understanding how falloff impacts the damage, one also understands how tracking impacts it, even if that's not immediately obvious.
The equation also shows that the reduction of hit chance from falloff and tracking respectively follow the same behaviour. This is because they both look like ''0.5''<sup>(something / x)<sup>2</sup></sup>, where x is either tracking or falloff. The only differance between them are the input values, the result is the same.


Difficult example: At optimal+falloff a turret has 50% chance to hit. Against a target with the same angular velocity (rad/s) as a turrets tracking (multiplied with the targets size and divided by 40 000) (rad/s), a turret has 50% chance to hit.
Example: At a range equal to optimal+falloff the range part of the equation becomes ''0.5''<sup>''1''</sup>, which means a 50% chance to hit. Against a target with the same angular velocity (rad/s) as a turrets tracking value multiplied with the targets size and divided by 40 000, the tracking part of the equation becomes ''0.5''<sup>''1''</sup>, which is also a 50% chance to hit. In the first case the full falloff range was used, in the second case the full turret tracking was used, and since they both behave the same way they ended up at the same hit chance.


===Falloff and optimal range===
===Falloff and optimal range===
With no hit chance loss from tracking, a target inside the optimal range of a turret will be hit 100% of the time.
With no hit chance loss from tracking, a target inside the optimal range of a turret will be hit 100% of the time.


Falloff is an additional range that goes beyond the optimal. Falloff is different than optimal in the sense that it reflects a gradual loss of hit chance. When a target is at optimal+falloff the hit chance is down to 50%. At optimal+(2 x falloff) the hit chance is down to just 6.25%, but it's important to note that hits are still possible.  
Falloff is an additional range that goes beyond the optimal. Falloff is different than optimal in the sense that it reflects a gradual loss of hit chance. When a target is at optimal+falloff the hit chance is down to 50%. At optimal+(2 x falloff) the hit chance is down to 6.25%, but it's important to note that hits are still possible.  


When using turrets that fight inside falloff ranges it can be useful to know that being at optimal+(falloff/3) results in -11% average damage, being at optimal+(falloff/2) results in -22% average damage and being at optimal+falloff results in -61% average damage (note: average damage falls faster than hit chance due to how the random damage interval is calculated, see below).
When using turrets that fight inside falloff ranges it can be useful to know that being at optimal+(falloff / 3) results in -11% average damage, being at optimal+(falloff / 2) results in -22% average damage and being at optimal+falloff results in -61% average damage (note: average damage falls faster than hit chance due to how the random damage interval is calculated, see below).


Falloff and optimal ranges are visible in turret info window. They are further modified by skills, ammo, modules, hull bonuses and incoming tracking disruptors. Target distance is visible on the overview.
Falloff and optimal ranges are visible in turret info window. They are further modified by skills, ammo, modules, hull bonuses and incoming tracking disruptors. Target distance is visible on the overview.
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Just as a circle can be described as an angle of 360°, it can also be described as an angle of 2&pi; radians. Meaning that one radian equals to (360/2&pi;) roughly 57°.
Just as a circle can be described as an angle of 360°, it can also be described as an angle of 2&pi; radians. Meaning that one radian equals to (360/2&pi;) roughly 57°.


The ingame overview can show the angular velocity of a target if you open the settings and tick a box under the tab called columns. Angular velocity is used to determine the penalty to the hit chance based on the turret's tracking ability. Relying on high angular velocities to stay alive is called speed tanking (not to be mixed up with kiting, which is to keep something at range). If an enemy is orbiting you, it is possible to use special maneuvers (like keep at range) or modules (like a web) to try to mess with the angular velocity, this can make it easier to hit an otherwise hard to track target.
The ingame overview can show the angular velocity of a target if you open the settings and tick a box under the tab called columns. Angular velocity is used to determine the penalty to the hit chance based on the turret's tracking ability. Relying on high angular velocities to stay alive is called speed tanking (not to be mixed up with kiting, which is to keep something at range). If an enemy is orbiting you, it is possible to use special maneuvers (like keep at range) or modules (like turning a web on and off) to try to mess with the angular velocity, this can make it easier to hit an otherwise hard to track target.


Angular velocity is calculated as ω=v<sub>t</sub>/d, where v<sub>t</sub> is tranversal velocity of the target relative to shooter and d is distance to target. The shooter and target will both have same angular velocity to each other.
Angular velocity is calculated as ω=v<sub>t</sub>/d, where v<sub>t</sub> is tranversal velocity of the target relative to shooter and d is distance to target. The shooter and target will both have same angular velocity to each other.
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The damage that a turret deal will be randomly spread around a fixed value called base damage. The base damage is calculated from the turret's Damage Multiplier attribute, the ammo's damage values, hull modifiers and skills.  
The damage that a turret deal will be randomly spread around a fixed value called base damage. The base damage is calculated from the turret's Damage Multiplier attribute, the ammo's damage values, hull modifiers and skills.  


===Randomness of damage===
===Random damage interval===
At the heart of each turret's damage output is a single randomly generated value between 0 and 1 that is several digits long. This random number is used '''both''' to determine if the turret hits the target and then to determine how much damage that hit actually did. If the random number is less than 0.01 (1% chance) it is a perfect hit and deals 300% of the base damage. A funny result of this is that when the hit chance is 1% or less, only misses and perfect hits can occur.
At the heart of each turret's damage output is a single randomly generated value between 0 and 1 that is several digits long. This random number is used '''both''' to determine if the turret hits the target and then to determine how much damage that hit actually did. If the random number is less than 0.01 (1% chance) it is a perfect hit and deals 300% of the base damage. A funny result of this is that when the hit chance is 1% or less, only misses and perfect hits can occur.


The damage modifier of the shot is calculated with the following formula, the first 0.01 of the random number interval is used for perfect hits which has a damage modifier of x3:
The damage modifier of the shot is calculated with the following formula, the first 0.01 of the random number interval is used for perfect hits which leads to a fixed damage modifier of x3:


Damage modifier = Random number[0.01,1] + 0.49
Damage modifier = Random number[0.01,1] + 0.49


The base damage is multiplied by this modifier to get the final damage. A turret with a 100% chance to hit will strike for 50% - 149% of its base damage in every non perfect hit. Since the same random number is used for determining a hit and doing the damage calculations the upper damage interval also goes down when the hit chance is decreased. Which means that the average damage done is reduced more than the hit chance.
The base damage is multiplied by the damage modifier to get the final damage.  


Example: With a 70% hit chance a turrets damage interval is 50% - 119% of base damage with all non perfect hits, so the average damage done is not 70% of base damage, it is just 61.3% (69%*(50%+119%)/2+1%*3) of the base damage.
The combat log will show the quality of a hit as follows
 
The quality of a hit is also shown in the combat log.


{| class="wikitable" border=0
{| class="wikitable" border=0
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|}


'''Example:'''
===Average damage===
A small gatling laser turret fires on target. The chance to hit is 0.8981. The EVE server rolls a random number between 0 and 1, and gets 0.6573—this is less than the chance to hit so the shot lands on the target. At this point 0.49 is added to the random number which then becomes 1.1473. The turret had a damage multiplier of ×2.1 and the ammo does 4 EM and 2 Thermal, so the base damage is 2.1 multiplied with 6 (4+2), which is 12.6. After multiplying this with the random number we get the raw damage, which is 1.1473&nbsp;×&nbsp;12.6&nbsp;=&nbsp;14.456. This damage will become lower when resistances have been accounted for. In the combat log the hit will be described as "well aimed."
A turret with a hit chance of 100% will strike for 50% - 149% of its base damage in every non perfect hit. But since the same random number is used to determine a hit or miss as well as the damage modifier, this means that the upper damage interval will begin to shrink as well when the hit chance is decreased. The average damage is thus reduced in two ways, firstly by having some shots miss and deal no damage at all, and secondly by having the upper damage interval decrease as well. So the average damage will always be reduced more than the hit chance is.
 
Example: When the hit chance of a turret is 70% the damage interval has shrunk to 50% - 119% for all non perfect hits. When combined, these two things results in an average damage of just 61.3% (69%*(50%+119%)/2+1%*3) of the base damage.


==Grouping guns, does it affect the damage?==
==Grouping guns, does it change the damage?==
No. Even if the guns are grouped on your screen, they are still treated separately. This can be seen by collecting damage data and comparing that with the expected damage distribution, it's very clear that it's a combination of several separate turret shots instead of a single one. It can also be deduced by looking at the turret group's damage output when shooting at hard to hit objects, like things deep into falloff, it's then possible to tell when one, two or more guns hit the target.
No. Even if the guns are grouped on your screen, they are still treated separately. This can be seen by collecting damage data and comparing that with the expected damage distribution, it's very clear that it's a combination of several separate turret shots instead of a single one. It can also be deduced by looking at the turret group's damage output when shooting at hard to hit objects, like things deep into falloff, it's then possible to tell when one, two or more guns hit the target.