Merge pull request #5793 from acemod/advanced-ballistics-muzzle-veloc…

…ity-variation

Advanced Ballistics - Muzzle velocity variation

addons/advanced_ballistics/ACE_Settings.hpp

@@ -43,6 +43,13 @@ class ACE_Settings {
         value = 0;
     };
     */
+    class GVAR(muzzleVelocityVariationEnabled) {
+        category = CSTRING(DisplayName);
+        displayName = CSTRING(muzzleVelocityVariationEnabled_DisplayName);
+        description = CSTRING(muzzleVelocityVariationEnabled_Description);
+        typeName = "BOOL";
+        value = 1;
+    }; 
     class GVAR(ammoTemperatureEnabled) {
         category = CSTRING(DisplayName);
         displayName = CSTRING(ammoTemperatureEnabled_DisplayName);

addons/advanced_ballistics/CfgVehicles.hpp

@@ -49,6 +49,12 @@ class CfgVehicles {
                 defaultValue = 0;
             };
             */
+            class muzzleVelocityVariationEnabled {
+                displayName = CSTRING(muzzleVelocityVariation_DisplayName);
+                description = CSTRING(muzzleVelocityVariation_Description);
+                typeName = "BOOL";
+                defaultValue = 1;
+            };
             class ammoTemperatureEnabled {
                 displayName = CSTRING(ammoTemperatureEnabled_DisplayName);
                 description = CSTRING(ammoTemperatureEnabled_Description);

addons/advanced_ballistics/functions/fnc_diagnoseWeapons.sqf

@@ -64,7 +64,7 @@ for "_i" from 0 to (count _cfgWeapons)-1 do {
                 if (isNil "_WeaponCacheEntry") then {
                      _WeaponCacheEntry = _weapon call FUNC(readWeaponDataFromConfig);
                 };
-                _AmmoCacheEntry params ["_airFriction", "_caliber", "_bulletLength", "_bulletMass", "_transonicStabilityCoef", "_dragModel", "_ballisticCoefficients", "_velocityBoundaries", "_atmosphereModel", "_ammoTempMuzzleVelocityShifts", "_muzzleVelocityTable", "_barrelLengthTable"];
+                _AmmoCacheEntry params ["_airFriction", "_caliber", "_bulletLength", "_bulletMass", "_transonicStabilityCoef", "_dragModel", "_ballisticCoefficients", "_velocityBoundaries", "_atmosphereModel", "_ammoTempMuzzleVelocityShifts", "_muzzleVelocityTable", "_barrelLengthTable", "_muzzleVelocityVariationSD"];
                 _WeaponCacheEntry params ["_barrelTwist", "_twistDirection", "_barrelLength"];
 
                 private _barrelVelocityShift = [_barrelLength, _muzzleVelocityTable, _barrelLengthTable, _vanillaInitialSpeed] call FUNC(calculateBarrelLengthVelocityShift);

addons/advanced_ballistics/functions/fnc_handleFired.sqf

@@ -48,36 +48,36 @@ if (isNil "_WeaponCacheEntry") then {
      _WeaponCacheEntry = _weapon call FUNC(readWeaponDataFromConfig);
 };
 
-_AmmoCacheEntry params ["_airFriction", "_caliber", "_bulletLength", "_bulletMass", "_transonicStabilityCoef", "_dragModel", "_ballisticCoefficients", "_velocityBoundaries", "_atmosphereModel", "_ammoTempMuzzleVelocityShifts", "_muzzleVelocityTable", "_barrelLengthTable"];
+_AmmoCacheEntry params ["_airFriction", "_caliber", "_bulletLength", "_bulletMass", "_transonicStabilityCoef", "_dragModel", "_ballisticCoefficients", "_velocityBoundaries", "_atmosphereModel", "_ammoTempMuzzleVelocityShifts", "_muzzleVelocityTable", "_barrelLengthTable", "_muzzleVelocityVariationSD"];
 _WeaponCacheEntry params ["_barrelTwist", "_twistDirection", "_barrelLength"];
 
+private _temperature = nil; // We need the variable in this scope. So we need to init it here.
+
+private _ammoCount = _unit ammo _muzzle;
 
 private _bulletVelocity = velocity _projectile;
 private _muzzleVelocity = vectorMagnitude _bulletVelocity;
 
-private _barrelVelocityShift = 0;
 if (GVAR(barrelLengthInfluenceEnabled)) then {
-    _barrelVelocityShift = [_barrelLength, _muzzleVelocityTable, _barrelLengthTable, _muzzleVelocity] call FUNC(calculateBarrelLengthVelocityShift);
+    _muzzleVelocity = _muzzleVelocity + ([_barrelLength, _muzzleVelocityTable, _barrelLengthTable, _muzzleVelocity] call FUNC(calculateBarrelLengthVelocityShift));
 };
-
-private _ammoTemperatureVelocityShift = 0;
-private _temperature = nil; //Need the variable in this scope. So we need to init it here.
-
 if (GVAR(ammoTemperatureEnabled)) then {
     _temperature = ((getPosASL _unit) select 2) call EFUNC(weather,calculateTemperatureAtHeight);
-    _ammoTemperatureVelocityShift = ([_ammoTempMuzzleVelocityShifts, _temperature] call FUNC(calculateAmmoTemperatureVelocityShift));
+    _muzzleVelocity = _muzzleVelocity + ([_ammoTempMuzzleVelocityShifts, _temperature] call FUNC(calculateAmmoTemperatureVelocityShift));
 };
-
-if (GVAR(ammoTemperatureEnabled) || GVAR(barrelLengthInfluenceEnabled)) then {
-    private _muzzleVelocityShift = _barrelVelocityShift + _ammoTemperatureVelocityShift;
-    TRACE_4("shift",_muzzleVelocity,_muzzleVelocityShift, _barrelVelocityShift, _ammoTemperatureVelocityShift);
-    if (_muzzleVelocityShift != 0) then {
-        _muzzleVelocity = _muzzleVelocity + _muzzleVelocityShift;
-        _bulletVelocity = _bulletVelocity vectorAdd ((vectorNormalized _bulletVelocity) vectorMultiply (_muzzleVelocityShift));
-        _projectile setVelocity _bulletVelocity;
-    };
+if (GVAR(muzzleVelocityVariationEnabled)) then {
+    private _time = round (CBA_missionTime / 2);
+    // Generate seed from publicly known values (via Cantor pairing function)
+    private _seed = 0.5 * (_time + _ammoCount) * (_time + _ammoCount + 1) + _ammoCount;
+    // Generate normally distributed random number (via Box–Muller transform)
+    private _z = sqrt(-2.0 * log(0.00000001 max (-_seed random 1))) * cos(_seed random 360);
+
+    _muzzleVelocity = _muzzleVelocity * (_z * _muzzleVelocityVariationSD + 1);
 };
 
+_bulletVelocity = (vectorNormalized _bulletVelocity) vectorMultiply _muzzleVelocity;
+_projectile setVelocity _bulletVelocity;
+
 if (_abort) exitWith {
     if (missionNamespace getVariable [QEGVAR(windDeflection,enabled), false]) then {
         EGVAR(windDeflection,trackedBullets) pushBack [_projectile, getNumber(configFile >> "CfgAmmo" >> _ammo >> "airFriction")];
@@ -108,8 +108,6 @@ if (_caliber * _bulletLength * _bulletMass * _barrelTwist > 0) then {
 
 GVAR(currentbulletID) = (GVAR(currentbulletID) + 1) % 10000;
 
-private _ammoCount = _unit ammo _muzzle;
-
 "ace_advanced_ballistics" callExtension format["new:%1:%2:%3:%4:%5:%6:%7:%8:%9:%10:%11:%12:%13:%14:%15:%16:%17:%18", GVAR(currentbulletID), _ammoCount, _airFriction, _ballisticCoefficients, _velocityBoundaries, _atmosphereModel, _dragModel, _stabilityFactor, _twistDirection, _transonicStabilityCoef, getPosASL _projectile, _bulletVelocity, EGVAR(common,mapLatitude), EGVAR(weather,currentTemperature), EGVAR(common,mapAltitude), EGVAR(weather,currentHumidity), EGVAR(weather,currentOvercast), CBA_missionTime toFixed 6];
 
 GVAR(allBullets) pushBack [_projectile, _caliber, _bulletTraceVisible, GVAR(currentbulletID)];

addons/advanced_ballistics/functions/fnc_initModuleSettings.sqf

@@ -22,6 +22,7 @@ params ["_logic","_units", "_activated"];
 if !(_activated) exitWith {};
 
 [_logic, QGVAR(enabled), "enabled"] call EFUNC(common,readSettingFromModule);
+[_logic, QGVAR(muzzleVelocityVariationEnabled), "muzzleVelocityVariationEnabled"] call EFUNC(common,readSettingFromModule);
 [_logic, QGVAR(ammoTemperatureEnabled), "ammoTemperatureEnabled"] call EFUNC(common,readSettingFromModule);
 [_logic, QGVAR(barrelLengthInfluenceEnabled), "barrelLengthInfluenceEnabled"] call EFUNC(common,readSettingFromModule);
 [_logic, QGVAR(bulletTraceEnabled), "bulletTraceEnabled"] call EFUNC(common,readSettingFromModule);

addons/advanced_ballistics/functions/fnc_readAmmoDataFromConfig.sqf

@@ -49,6 +49,10 @@ private _atmosphereModel = getText(_ammoConfig >> "ACE_standardAtmosphere");
 if (_atmosphereModel isEqualTo "") then {
     _atmosphereModel = "ICAO";
 };
+private _muzzleVelocityVariationSD = DEFAULT_MUZZLE_VELOCITY_VARIATION_SD;
+if (isNumber (_ammoConfig >> "ACE_muzzleVelocityVariationSD")) then {
+    _muzzleVelocityVariationSD = getNumber(_ammoConfig >> "ACE_muzzleVelocityVariationSD") / 100;
+};
 private _ammoTempMuzzleVelocityShifts = getArray(_ammoConfig >> "ACE_ammoTempMuzzleVelocityShifts");
 private _muzzleVelocityTable = getArray(_ammoConfig >> "ACE_muzzleVelocities");
 private _barrelLengthTable = getArray(_ammoConfig >> "ACE_barrelLengths");
@@ -89,7 +93,7 @@ if ((_typicalSpeed > 0) && {_typicalSpeed < 360}) then {
     };
 };
 
-private _result = [_airFriction, _caliber, _bulletLength, _bulletMass, _transonicStabilityCoef, _dragModel, _ballisticCoefficients, _velocityBoundaries, _atmosphereModel, _ammoTempMuzzleVelocityShifts, _muzzleVelocityTable, _barrelLengthTable];
+private _result = [_airFriction, _caliber, _bulletLength, _bulletMass, _transonicStabilityCoef, _dragModel, _ballisticCoefficients, _velocityBoundaries, _atmosphereModel, _ammoTempMuzzleVelocityShifts, _muzzleVelocityTable, _barrelLengthTable, _muzzleVelocityVariationSD];
 
 uiNamespace setVariable [format[QGVAR(%1), _this], _result];
 

addons/advanced_ballistics/script_component.hpp

@@ -28,4 +28,7 @@
 #define STD_AIR_DENSITY_ICAO 1.22498
 #define STD_AIR_DENSITY_ASM 1.20885
 
+ // Standard deviation of the default muzzle velocity variation (0.3%)
+#define DEFAULT_MUZZLE_VELOCITY_VARIATION_SD 0.003
+
 #define EXTENSION_REQUIRED_VERSION "1.0"

addons/advanced_ballistics/stringtable.xml

@@ -241,6 +241,14 @@
             <Chinese>在全自動模式開火時,關閉先進彈道系統</Chinese>
             <Chinesesimp>在全自动模式开火时,关闭先进弹道系统</Chinesesimp>
         </Key>
+        <Key ID="STR_ACE_Advanced_Ballistics_muzzleVelocityVariationEnabled_DisplayName">
+            <English>Enable Muzzle Velocity Variation</English>
+            <German>Variation der Mündungsgeschwindigkeit aktivieren</German>
+        </Key>
+        <Key ID="STR_ACE_Advanced_Ballistics_muzzleVelocityVariationEnabled_Description">
+            <English>Simulates slight variations in muzzle velocity between each shot</English>
+            <German>Simuliert leichte Variationen der Mündungsgeschwindigkeit zwischen jedem Schuss.</German>
+        </Key>
         <Key ID="STR_ACE_Advanced_Ballistics_ammoTemperatureEnabled_DisplayName">
             <English>Enable Ammo Temperature Simulation</English>
             <Polish>Symulacja temp. amunicji</Polish>

addons/ballistics/CfgAmmo.hpp

@@ -27,6 +27,7 @@ class CfgAmmo {
         ACE_caliber=5.69;
         ACE_bulletLength=23.012;
         ACE_bulletMass=4.9896;
+        ACE_muzzleVelocityVariationSD=0.4;
         ACE_ammoTempMuzzleVelocityShifts[]={-26.55, -25.47, -22.85, -20.12, -16.98, -12.80, -7.64, -1.53, 5.96, 15.17, 26.19};
         ACE_ballisticCoefficients[]={0.361};
         ACE_velocityBoundaries[]={};
@@ -123,6 +124,7 @@ class CfgAmmo {
         ACE_caliber=6.706;
         ACE_bulletLength=34.646;
         ACE_bulletMass=9.0072;
+        ACE_muzzleVelocityVariationSD=0.35;
         ACE_ammoTempMuzzleVelocityShifts[]={-26.55, -25.47, -22.85, -20.12, -16.98, -12.80, -7.64, -1.53, 5.96, 15.17, 26.19};
         ACE_ballisticCoefficients[]={0.290};
         ACE_velocityBoundaries[]={};
@@ -137,6 +139,7 @@ class CfgAmmo {
         ACE_caliber=6.706;
         ACE_bulletLength=36.22;
         ACE_bulletMass=9.072;
+        ACE_muzzleVelocityVariationSD=0.3;
         ACE_ammoTempMuzzleVelocityShifts[]={-26.55, -25.47, -22.85, -20.12, -16.98, -12.80, -7.64, -1.53, 5.96, 15.17, 26.19};
         ACE_ballisticCoefficients[]={0.317};
         ACE_velocityBoundaries[]={};
@@ -177,6 +180,7 @@ class CfgAmmo {
         ACE_caliber=7.823;
         ACE_bulletLength=31.496;
         ACE_bulletMass=11.34;
+        ACE_muzzleVelocityVariationSD=0.4;
         ACE_ammoTempMuzzleVelocityShifts[]={-26.55, -25.47, -22.85, -20.12, -16.98, -12.80, -7.64, -1.53, 5.96, 15.17, 26.19};
         ACE_ballisticCoefficients[]={0.243};
         ACE_velocityBoundaries[]={};
@@ -193,6 +197,7 @@ class CfgAmmo {
         ACE_caliber=7.823;
         ACE_bulletLength=31.496;
         ACE_bulletMass=11.34;
+        ACE_muzzleVelocityVariationSD=0.45;
         ACE_ammoTempMuzzleVelocityShifts[]={-5.3, -5.1, -4.6, -4.2, -3.4, -2.6, -1.4, -0.3, 1.4, 3.0, 5.2};
         ACE_ballisticCoefficients[]={0.243};
         ACE_velocityBoundaries[]={};
@@ -209,6 +214,7 @@ class CfgAmmo {
         ACE_caliber=7.823;
         ACE_bulletLength=31.496;
         ACE_bulletMass=8.424;
+        ACE_muzzleVelocityVariationSD=0.45;
         ACE_ammoTempMuzzleVelocityShifts[]={-2.655, -2.547, -2.285, -2.012, -1.698, -1.280, -0.764, -0.153, 0.596, 1.517, 2.619};
         ACE_ballisticCoefficients[]={0.377};
         ACE_velocityBoundaries[]={};
@@ -257,6 +263,7 @@ class CfgAmmo {
         ACE_caliber=7.823;
         ACE_bulletLength=34.366;
         ACE_bulletMass=12.312;
+        ACE_muzzleVelocityVariationSD=0.45;
         ACE_ammoTempMuzzleVelocityShifts[]={-5.3, -5.1, -4.6, -4.2, -3.4, -2.6, -1.4, -0.3, 1.4, 3.0, 5.2};
         ACE_ballisticCoefficients[]={0.268};
         ACE_velocityBoundaries[]={};
@@ -273,6 +280,7 @@ class CfgAmmo {
         ACE_caliber=7.823;
         ACE_bulletLength=37.821;
         ACE_bulletMass=14.256;
+        ACE_muzzleVelocityVariationSD=0.45;
         ACE_ammoTempMuzzleVelocityShifts[]={-5.3, -5.1, -4.6, -4.2, -3.4, -2.6, -1.4, -0.3, 1.4, 3.0, 5.2};
         ACE_ballisticCoefficients[]={0.310};
         ACE_velocityBoundaries[]={};
@@ -289,6 +297,7 @@ class CfgAmmo {
         ACE_caliber=7.823;
         ACE_bulletLength=40.691;
         ACE_bulletMass=14.904;
+        ACE_muzzleVelocityVariationSD=0.35;
         ACE_ammoTempMuzzleVelocityShifts[]={-26.55, -25.47, -22.85, -20.12, -16.98, -12.80, -7.64, -1.53, 5.96, 15.17, 26.19};
         ACE_ballisticCoefficients[]={0.368};
         ACE_velocityBoundaries[]={};
@@ -376,6 +385,7 @@ class CfgAmmo {
         ACE_caliber=9.296;
         ACE_bulletLength=34.29;
         ACE_bulletMass=14.904;
+        ACE_muzzleVelocityVariationSD=0.4;
         ACE_ammoTempMuzzleVelocityShifts[]={-26.55, -25.47, -22.85, -20.12, -16.98, -12.80, -7.64, -1.53, 5.96, 15.17, 26.19};
         ACE_ballisticCoefficients[]={0.368};
         ACE_velocityBoundaries[]={};
@@ -392,6 +402,7 @@ class CfgAmmo {
         ACE_bulletLength=55.1942;
         ACE_bulletMass=27.1507; // 419 gr
         ACE_transonicStabilityCoef=1;
+        ACE_muzzleVelocityVariationSD=0.2;
         ACE_ammoTempMuzzleVelocityShifts[]={-26.55, -25.47, -22.85, -20.12, -16.98, -12.80, -7.64, -1.53, 5.96, 15.17, 26.19};
         ACE_ballisticCoefficients[]={0.434};
         ACE_velocityBoundaries[]={};
@@ -409,6 +420,7 @@ class CfgAmmo {
         ACE_bulletLength=41.4528;
         ACE_bulletMass=19.7637; // 305 gr
         ACE_transonicStabilityCoef=1;
+        ACE_muzzleVelocityVariationSD=0.2;
         ACE_ammoTempMuzzleVelocityShifts[]={-26.55, -25.47, -22.85, -20.12, -16.98, -12.80, -7.64, -1.53, 5.96, 15.17, 26.19};
         ACE_ballisticCoefficients[]={0.279};
         ACE_velocityBoundaries[]={};
@@ -423,6 +435,7 @@ class CfgAmmo {
         ACE_caliber=8.585;
         ACE_bulletLength=39.573;
         ACE_bulletMass=16.2;
+        ACE_muzzleVelocityVariationSD=0.3;
         ACE_ammoTempMuzzleVelocityShifts[]={-26.55, -25.47, -22.85, -20.12, -16.98, -12.80, -7.64, -1.53, 5.96, 15.17, 26.19};
         ACE_ballisticCoefficients[]={0.322};
         ACE_velocityBoundaries[]={};
@@ -451,6 +464,7 @@ class CfgAmmo {
         ACE_caliber=8.585;
         ACE_bulletLength=43.18;
         ACE_bulletMass=19.44;
+        ACE_muzzleVelocityVariationSD=0.3;
         ACE_ammoTempMuzzleVelocityShifts[]={-26.55, -25.47, -22.85, -20.12, -16.98, -12.80, -7.64, -1.53, 5.96, 15.17, 26.19};
         ACE_ballisticCoefficients[]={0.368};
         ACE_velocityBoundaries[]={};
@@ -467,6 +481,7 @@ class CfgAmmo {
         ACE_caliber=8.585;
         ACE_bulletLength=38.989;
         ACE_bulletMass=16.3941242;
+        ACE_muzzleVelocityVariationSD=0.4;
         ACE_ammoTempMuzzleVelocityShifts[]={-26.55, -25.47, -22.85, -20.12, -16.98, -12.80, -7.64, -1.53, 5.96, 15.17, 26.19};
         ACE_ballisticCoefficients[]={0.290};
         ACE_velocityBoundaries[]={};
@@ -499,6 +514,7 @@ class CfgAmmo {
         ACE_caliber=12.954;
         ACE_bulletLength=58.674;
         ACE_bulletMass=41.9256;
+        ACE_muzzleVelocityVariationSD=0.35;
         ACE_ammoTempMuzzleVelocityShifts[]={-26.55, -25.47, -22.85, -20.12, -16.98, -12.80, -7.64, -1.53, 5.96, 15.17, 26.19};
         ACE_ballisticCoefficients[]={0.670};
         ACE_velocityBoundaries[]={};
@@ -516,6 +532,7 @@ class CfgAmmo {
         ACE_caliber=12.954;
         ACE_bulletLength=58.674;
         ACE_bulletMass=41.9904;
+        ACE_muzzleVelocityVariationSD=0.4;
         ACE_ammoTempMuzzleVelocityShifts[]={-26.55, -25.47, -22.85, -20.12, -16.98, -12.80, -7.64, -1.53, 5.96, 15.17, 26.19};
         ACE_ballisticCoefficients[]={0.670};
         ACE_velocityBoundaries[]={};
@@ -531,6 +548,7 @@ class CfgAmmo {
         ACE_caliber=12.954;
         ACE_bulletLength=64.516;
         ACE_bulletMass=48.6;
+        ACE_muzzleVelocityVariationSD=0.2;
         ACE_ammoTempMuzzleVelocityShifts[]={-26.55, -25.47, -22.85, -20.12, -16.98, -12.80, -7.64, -1.53, 5.96, 15.17, 26.19};
         ACE_ballisticCoefficients[]={1.050};
         ACE_velocityBoundaries[]={};

addons/scopes/functions/fnc_calculateZeroAngleCorrection.sqf

@@ -53,7 +53,7 @@ private _trueZero = if (!_advancedBallistics) then {
          _WeaponCacheEntry = _weapon call EFUNC(advanced_ballistics,readWeaponDataFromConfig);
     };
 
-    _AmmoCacheEntry params ["_airFriction", "_caliber", "_bulletLength", "_bulletMass", "_transonicStabilityCoef", "_dragModel", "_ballisticCoefficients", "_velocityBoundaries", "_atmosphereModel", "_ammoTempMuzzleVelocityShifts", "_muzzleVelocityTable", "_barrelLengthTable"];
+    _AmmoCacheEntry params ["_airFriction", "_caliber", "_bulletLength", "_bulletMass", "_transonicStabilityCoef", "_dragModel", "_ballisticCoefficients", "_velocityBoundaries", "_atmosphereModel", "_ammoTempMuzzleVelocityShifts", "_muzzleVelocityTable", "_barrelLengthTable", "_muzzleVelocityVariationSD"];
     _WeaponCacheEntry params ["_barrelTwist", "_twistDirection", "_barrelLength"];
 
     if (missionNamespace getVariable [QEGVAR(advanced_ballistics,barrelLengthInfluenceEnabled), false]) then {

docs/wiki/framework/advanced-ballistics-framework.md

@@ -56,11 +56,15 @@ class CfgAmmo {
         ACE_bulletLength = 23.012;  // Bullet Length in mm
         ACE_bulletMass = 4.0176;  // Mass in grams (example is roughly 62 grains)
 
+        // Standard deviation of the muzzle velocity variation in percent
+        // Example: With a muzzle velocity of 850 m/s and a standard deviation of 0.35%, 68% of the shots will be between 847 m/s and 853 m/s
+        ACE_muzzleVelocityVariationSD = 0.35;
+
         // Array of muzzle velocity shifts in m/s with 11 data points from -15 °C to 35 °C
         // Example: At 0°C the shift will be -21.0
         ACE_ammoTempMuzzleVelocityShifts[] = {-27.20, -26.44, -23.76, -21.00, -17.54, -13.10, -7.95, -1.62, 6.24, 15.48, 27.75};
 
-        //Array of ballistic coefficients (contains one element more than the velocity boundary array)
+        // Array of ballistic coefficients (contains one element more than the velocity boundary array)
         ACE_ballisticCoefficients[] = {0.151};
 
         ACE_velocityBoundaries[] = {};  // Array of velocity boundaries