Accuracy

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This page is going to be an in-depth, highly technical explanation of how all the different pieces of Accuracy all work together for weapons in Deep Rock Galactic. What will be described on this page explains how Accuracy works if the player is standing still. There are additional penalties to accuracy while moving, but this topic is already complex enough without having to account for them.

Overview[edit | edit source]

In the most abstract terms, Accuracy has two moving parts: the "bounding region" section1 that governs where pellets can be fired when the trigger gets pulled, and the "recoil" section that determines how far the bounding region gets displaced from the Original Aim Axis. At the start of the firing sequence, there is no Recoil so the center of the bounding region is perfectly aligned with the Original Aim Axis.

For the majority of hitscan weapons2, firing a shot causes the game to get the current horizontal and vertical sizes of the bounding region and use them to create an ellipse. All pellets fired per shot start with their trajectories perfectly aligned to the center of the ellipse, and then they get randomly displaced to anywhere within the bounding ellipse. The game does not favor putting the pellets closer to the center of the ellipse; it is a random roll for each individual pellet.

If the current Total Recoil is greater than zero, then the game first displaces the center of the bounding ellipse from the Original Aim Axis before performing its random pellet distribution.


1. NOTE: what is referred to as the "bounding region" section is not referring to the crosshairs displayed on-screen in the player's HUD. Those are just approximations to help the player aim; they are not representative of internal values.

2. Autocannon, Boomstick, and Zhukovs are the three exceptions. They all use rectangular bounding regions, instead of ellipses.

Terminology[edit | edit source]

  • Base Spread: This is the minimum bounding region (either ellipse or rectangle) across which pellets can be randomly distributed. It is the Spread value used when you fire the first shot while standing still.
  • Current Spread: This can only have a value between zero and Spread Difference, and is the current value of units that get added to Base Spread when the game fetches what the Horizontal and Vertical Spread values are.
  • Spread per Shot: Every time a shot is fired, this value will be added to Current Spread (cannot surpass Spread Difference).
  • Spread Recovery Speed: If Current Spread is greater than zero (as in, at least one shot has been fired recently), then this is the value of how many Spread Units are subtracted per second from Current Spread until it returns to zero.
  • Spread Difference: This value governs the maximum bounding region size such that neither its vertical nor horizontal values can surpass Base Spread + Spread Difference. If a shot gets fired and the added Spread per Shot would make Current Spread exceed Spread Difference, Current Spread instead just gets set to the max value and some of the Spread per Shot is lost.
  • Max Spread: This value is equal to Base Spread + Spread Difference, and is the largest region that can be used by the weapon's pellet distribution.
  • Spread Curve: Certain weapons have a function that converts the Spread values from linear, intuitive functionality into non-linear outputs. It can be conceptualized as changing "Total Spread = Base Spread + Current Spread" to "Total Spread = Base Spread + SpreadCurve(Current Spread)".
  • Original Aim Axis (OAA): Before the first shot gets fired, the Original Aim Axis is the center of the player's screen (and by extension the crosshair displayed on the HUD). The OAA is the axis to which Recoil is perpetually trying to return. The OAA remains stationary relative to the player's HUD whenever Total Recoil is greater than zero such that moving the crosshair down to counteract recoil also moves OAA down, and when the Recoil is falling off the crosshair will fall back down to where the OAA has moved to.
  • Recoil per Shot: Every shot fired by hitscan weapons has an associated recoil value that displaces the center of the bounding region by a small amount and then returns back to zero over time.
  • Total Recoil: This is a rolling sum of all Recoil per Shots as time progresses. If only one shot was fired, then Total Recoil would be identical to one Recoil per Shot. However, if shots are fired faster than the Recoil per Shot can recover, then Total Recoil will continue to rise until it reaches an equilibrium where the amount of recoil being shed by the sum of all Recoil per Shots is equal to amount of recoil being gained by the next shot. Due to this rolling sum, increasing the weapon's Rate of Fire will also increase the maximum Total Recoil value because the equilibrium won't be reached as quickly.

Spread[edit | edit source]

Spread Variables Used[edit | edit source]

All of these variables can be found in the HitscanBaseComponent object associated with each weapon.

  • MaxHorizontalSpread
  • MaxVerticalSpread
  • SpreadPerShot
  • SpreadRecoveryPerSecond
  • MinSpread
  • MaxSpread

Spread Equations Used[edit | edit source]

Horizontal Base Spread = MaxHorizontalSpread

Vertical Base Spread = MaxVerticalSpread

Spread Difference = MaxSpread - MinSpread

Current Spread after firing a shot = min(Current Spread + Spread per Shot, Spread Difference)

Current Spread(t) while Current > Base = max(Base Spread, Current Spread - Spread Recovery Speed * t)

Converting Spread Units to Degrees[edit | edit source]

Similar to how the FoV setting in DRG can say "100 degrees" when in fact it's only 50 degrees deviation from the center, the Total Spread value is double of the useful value. That means a Base Spread of 3 would translate to 1.5 degrees, Total Spread of 12 would become 6 degrees, and so on. The halved values are far more useful for calculating the sizes of bounding regions at any given distance. As a result, in order to calculate the degrees of deviation from OAA, it's as simple as picking either Horizontal or Vertical Spread, getting the corresponding Base Spread value, add the Current Spread (MinSpread < Current Spread < MaxSpread), and then divide by 2 for ease of use in sin().

\[Degrees = \frac{Base Spread + Current Spread}{2}\]

Spread Full Model[edit | edit source]

  1. The player presses the Fire button
  2. The game fetches the current values of Horizontal Base Spread + Current Spread and Vertical Base Spread + Current Spread, and uses them to form a bounding region (either ellipse or rectangle). If the weapon has a Spread Curve, it changes the lookup to Base Spread + SpreadCurve(Current Spread)
  3. All pellets to be fired for this shot have their trajectories randomly displaced within the bounding region and then their hitscan collisions get checked
  4. The game tries to add the Spread per Shot to the Current Spread value. If that causes Current Spread to exceed the Spread Difference value, Current Spread gets set to Spread Difference instead.
  5. If Current Spread > 0 (equivalent to Current Spread + Base Spread > Base Spread), then the game starts subtracting Spread Recovery Speed units per second from Current Spread
  6. Repeat steps 1-5 for every shot in the magazine
  7. After enough time has passed, Spread Recovery Speed will reduce Current Spread all the way to zero, bringing the Total Spread back down to Base Spread.

Recoil[edit | edit source]

DRG has modeled the recoil of their guns to use a Critically Damped Harmonic Oscillator function.

Recoil Variables Used[edit | edit source]

All of these variables can be found in the RecoilSettings property of the AmmoDrivenWeapon object associated with each weapon.

  • Mass
  • SpringStiffness
  • RecoilPitch
  • RecoilYaw
  • CanRecoilDown

NOTE: CanRecoilDown is only true for Minigun, Autocannon, and Zhukovs. For all other weapons, the recoil can only go up, left, or right.

Recoil Equations Used[edit | edit source]

Natural Frequency[edit | edit source]

  • Let Mass be represented by 'M'
  • Let SpringStiffness be represented by 'S'

\[\omega_{n} = \sqrt{\frac{S}{M}}\]

Total Initial Velocity[edit | edit source]

  • Let RecoilPitch be represented by 'V'
  • Let RecoilYaw be represented by 'H'

\[v_{i} = \sqrt{V^{2} + H^{2}}\]

Recoil per Shot over time[edit | edit source]

\[R(t) = e^{-\omega_{n}*t} * (v_{i} * t)\]

NOTE: this equation returns the degrees of deviation of how far the center of the crosshair should move away from the OAA for this shot.

Example plot using Subata's default variables:

Example Recoil Per Shot Graph.png

Maximum Recoil per Shot[edit | edit source]

\[Max = R(\frac{1}{\omega_{n}})\]

Time for Recoil per Shot to reach 0.1[edit | edit source]

\[End = \frac{-W_{-1}[\frac{-\omega_{n} * 0.1}{v_{i}}]}{\omega_{n}}\]

NOTE: the \[W_{-1}[...]\] is shorthand for the LambertW function using k=-1

Recoil Full Model[edit | edit source]

  1. A shot is fired
  2. RecoilPitch is fetched and chooses between the up and down direction (if CanRecoilDown=True, else only up direction can be chosen), and RecoilYaw is fetched and chooses between either left or right direction.
  3. Using RecoilPitch, Mass, and SpringStiffness a Recoil(t) function is made to track the vertical recoil of the shot that was just fired. Similarly, RecoilYaw is used in a Recoil(t) function to track the horizontal recoil.
  4. The Total Vertical Recoil and Total Horizontal Recoil values start tracking their new Recoil(t) functions, respectively, and add the current degrees of deviation to their totals.
  5. When Recoil(t) falls below a certain value (modeled as 0.1), the two Total Recoil trackers discard that function from their running sums.
  6. The player's HUD is moved off of the OAA vertically by Total Vertical Recoil degrees and horizontally by Total Horizontal Recoil degrees. This has the added effect of moving the weapon's crosshair center off of the OAA too.
  7. Repeat steps 1-6 for every shot in the magazine
  8. After enough time has passed, all of the individual Recoil(t) functions will have fallen below the threshold (0.1 in this model) and both Total Recoil values will return to zero, also returning the HUD to the OAA.

Internal values per weapon[edit | edit source]

Table of baseline values[edit | edit source]

Disclaimer: these values were last updated using Update 31, Hotfix 5.

Weapon Name MaxHorizontalSpread MaxVerticalSpread SpreadPerShot SpreadRecoveryPerSecond MinSpread MaxSpread RecoilPitch RecoilYaw Mass SpringStiffness CanRecoilDown
Subata 1.5 1.5 1.5 7.5 0 3 30 10 1 60 False
Shotgun 12 6 0 12 6 8 55 40 4 75 False
SMG 3 3 1.5 10 0 4 [35, 45] 7 1 40 False
Minigun 5 5 0.2 1 0 3.5 10 10 1 150 True
Autocannon 22 8 0 5 0 0 30 40 1 200 True
Revolver 1.5 1.5 7 6 0 8 130 10 2 65 False
BRT 2.25 2.25 1.2 5 0 4 30 10 1 70 False
GK2 0.9 0.9 1.4 8.1 0 4.2 35 5 1 50 False
M1000 1 1 3 8.5 0 5 50 5 4 70 False
Boomstick 35 10 0 5 0 5 120 10 2 100 False
Zhukovs 36 5 0 30 0 20 20 20 1 100 True

Tables of mods' and overclocks' effects[edit | edit source]

Disclaimer: these values were last updated using Update 31, Hotfix 5.

Subata[edit | edit source]

Upgrade Name Upgrade Effects
T1.A "Improved Alignment" x0 MaxHorizontalSpread
x0 MaxVerticalSpread
T3.B "Recoil Compensator" -0.3 SpreadPerShot
x0.5 RecoilPitch
x0.5 RecoilYaw
OC "Automatic Fire" x2.0 MaxHorizontalSpread
x2.0 MaxVerticalSpread
x2.5 RecoilPitch
x2.5 RecoilYaw

Shotgun[edit | edit source]

Upgrade Name Upgrade Effects
T2.C "Choke" x0.5 MaxHorizontalSpread
x0.5 MaxVerticalSpread
T3.A "Recoil Dampener" x0.4 RecoilPitch
x0.4 RecoilYaw
OC "Magnetic Pellet Alignment" x0.5 MaxHorizontalSpread
x0.5 MaxVerticalSpread
OC "Cycle Overload" x1.5 MaxHorizontalSpread
x1.5 MaxVerticalSpread
OC "Mini Shells" x0.5 RecoilPitch
x0.5 RecoilYaw

SMG[edit | edit source]

Upgrade Name Upgrade Effects
T2.B "Recoil Dampener" x0.5 RecoilPitch
x0.5 RecoilYaw
OC "Super-Slim Rounds" x0.8 MaxHorizontalSpread
x0.8 MaxVerticalSpread
OC "EM Refire Booster x1.5 MaxHorizontalSpread
x1.5 MaxVerticalSpread

Minigun[edit | edit source]

Upgrade Name Upgrade Effects
T1.C "Improved Platform Stability" x0.2 MaxHorizontalSpread
x0.2 MaxVerticalSpread
OC "Exhaust Vectoring" x2.5 MaxHorizontalSpread
x2.5 MaxVerticalSpread
OC "Bullet Hell" x6.0 MaxHorizontalSpread
x6.0 MaxVerticalSpread

Autocannon[edit | edit source]

Upgrade Name Upgrade Effects
T2.A "Tighter Barrel Alignment x0.7 MaxHorizontalSpread
x0.7 MaxVerticalSpread
OC "Big Bertha" x0.7 MaxHorizontalSpread
x0.7 MaxVerticalSpread

Revolver[edit | edit source]

Upgrade Name Upgrade Effects
T1.B "Perfect Weight Balance" x0.3 MaxHorizontalSpread
x0.3 MaxVerticalSpread
T2.B "Floating Barrel" -5.6 SpreadPerShot
x0.75 RecoilPitch
x0.75 RecoilYaw
T5.A "Dead-Eye" Removes movement penalty
OC "Six Shooter" x1.5 MaxHorizontalSpread
x1.5 MaxVerticalSpread
OC "Elephant Rounds x0.5 MaxHorizontalSpread
x0.5 MaxVerticalSpread
+5 SpreadPerShot
+4 MaxSpread
x1.5 RecoilPitch
x1.5 RecoilYaw
+3.5 Mass

BRT[edit | edit source]

Upgrade Name Upgrade Effects
T1.B "Floating Barrel" x0.7 MaxHorizontalSpread
x0.7 MaxVerticalSpread
x0.6 SpreadPerShot
T2.A "Recoil Dampener" x0.5 RecoilPitch
x0.5 RecoilYaw
OC "Micro Flechettes" x0.5 SpreadPershot
x0.5 RecoilPitch
x0.5 RecoilYaw
OC "Lead Spray" x4.0 MaxHorizontalSpread
x4.0 MaxVerticalSpread

GK2[edit | edit source]

Upgrade Name Upgrade Effects
T1.A "Gyro Stabilization" x0 MaxHorizontalSpread
x0 MaxVerticalSpread
T3.A "Floating Barrel" x0.5 RecoilPitch
x0.5 RecoilYaw
T5.B "Battle Cool" Sets SpreadRecoveryPerSecond = 100 for 1.5 sec after kill
OC "Compact Ammo" x0.7 RecoilPitch
x0.7 RecoilYaw
OC "Overclocked Firing Mechanism" x2.5 RecoilPitch
x2.5 RecoilYaw
OC "AI Stability Engine" +9 SpreadRecoveryPerSecond
x0 RecoilPitch
x0 RecoilYaw

M1000[edit | edit source]

Upgrade Name Upgrade Effects
T2.B "Better Weight Balance" -0.9 SpreadPerShot
x0.8 MaxSpread
x0.5 RecoilPitch
x0.5 RecoilYaw
OC "Hipster" -0.3 SpreadPerShot
x0.85 MaxSpread
x0.5 RecoilPitch
x0.5 RecoilYaw

Boomstick[edit | edit source]

Upgrade Name Upgrade Effects
OC "Shaped Shells" x0.65 MaxHorizontalSpread
x0.65 MaxVerticalSpread

Zhukovs[edit | edit source]

Upgrade Name Upgrade Effects
T3.B "Better Weight Balance" x0.5 MaxHorizontalSpread
x0.5 MaxVerticalSpread
OC "Gas Recycling" x1.5 MaxHorizontalSpread
x1.5 MaxVerticalSpread

List of all known Spread Curves[edit | edit source]

Minigun[edit | edit source]

Lead Storm Powered Minigun Spread Curve.png

Revolver[edit | edit source]

Bulldog Heavy Revolver Spread Curve.png

GK2[edit | edit source]

Deepcore GK2 Spread Curve.png

M1000[edit | edit source]

M1000 Classic Spread Curve.png