Tanks Config Guidelines – Arma 3

Intro

101 - How to set up a tank for Arma 3

Please be aware of our Arma 3 modding license: http://community.bistudio.com/wiki/Arma_3_Modding_License

Comparison to A2/OA tanks

• PhysX support
• Improved penetration materials
• More detailed Fire Geometry LODs
• Improved tweakability of HitPoints LODs

Comparison TankX vs. CarX

Arma_3_Cars_Config_Guidelines

• More wheels to be set up
• Few additional params used
• Less complicated Center of Mass tweaking
• Vehicle config parameter: tankTurnForce
• Wheel config parameter: side
• Importance of wheel config parameters: MOI, dampingRate, dampingRateInAir

Model requirements {p3d}

• A new PhysX LOD
  File:Test Tank 01: Geometry PhysX LOD.jpg

  Test_Tank_01: Geometry PhysX LOD
  • There needs to be a lod (4e13) consisting of convex components as simple as possible.
    • Current public Oxygen version doesn't support showing correct name of this lod and displays only Geometry instead. Don't be afraid of having two geometries, it's going to be fixed with new tools.
  • This lod should contain tank’s hull, turret and main gun only. Wheels representing the tracks are added by engine later

• Memory LOD
  File:Test Tank 01: Memory LOD PhysX Wheels.jpg

  Test_Tank_01: Memory LOD PhysX Wheels
  • There should be an axis for each wheel named wheel_X_Y_axis (X is 1 for left and 2 for right, Y is position of wheel from front), the name is defined in selected wheel as center.
  • There should be a point at the edge of each wheel named wheel_X_Y_bound which is used to determine wheel radius (distance from wheel axis is used for this) - there is no other need than placing the point at the edge, even memory points for tracks could be used for this, the name is defined in selected wheel as boundary

Model config changes {model.cfg}

• Similarly to PhysX related car changes, you will mostly need to change dampers:
  • Example:

 		{model.cfg}
 			class Wheel_podkoloL1 {
 				type = "translation";
 				source = "damper";
 				selection = "podkoloL1";
 				axis = "damper_axis"; // contains points [0,0,0] and [0,0,1]
 				animPeriod = 1;
 				minValue = 0;
 				maxValue = 1;
 				offset0 = 0.15; // = maxCompression
 				offset1 = -0.15; // = maxDroop
 				memory = 1;
 			};

• • Man-held turrets like commander’s gun on T-72 shouldn't be hidden until whole vehicle is destroyed - IK issues would crash the game

New config parameters {config.cpp}

Basic parameters

TankX uses most of the parameters present in cars. The tutorial will comment only parameters not described in car tutorial.

• <Type>: string
• <Default>: (required)
• simulation = "tankx";

Engine parameters

• <Type>: float
• <Default>: (required)
• tankTurnForce = 330000; // start from 11x vehicle mass and tweak until fine'

Wheel parameters

Wheels work almost exactly the same as in cars. However, please take note that the drive sprocket and idler wheels should not have suspension - set both maxDroop and maxCompression for them to 0. Remember to reset these values for road wheels so their dampers are active! Also you need to notify PhysX that the wheels are on either righ or left side, and that they are not steerable.

Wheel PX parameters

• steering = 0; - tank wheels are not turning
• side = “left”; - which side of tank the wheel belongs to
• dampingRate = 0.1; - damping rate while contacting with ground
• dampingRateInAir = 8000; - damping rate while in air. Use to tweak maximum speed. Tweak together with MOI.
• MOI = 50; - moment of inertia, set it so the tank does not accelerate or maintain speed indefinitely. Tweak together with dampingRateInAir.

Suspension parameters

• maxCompression = 0.15; // set to 0 for wheels that don’t have dampers
• maxDroop = 0.15;// set to 0 for wheels that don’t have dampers

Damage handling

Tanks offer differing protection levels for themselves and crew inside, depending on place you hit them. Balancing damage is usually most time-consuming task for armored vehicles.

Basic config

The tanks will usually have - at first sight - too much armor. But their vulnerable hitpoints will justify the effort, making it possible to destroy or neutralize armor with one shot.

Use armor to represent overall thickness of vehicle as seen by AI units, and armorStructural to finetune damage received.

Armour plates setup

Armour plates consist of convex components in Fire Geometry.

File:Test Tank 01: Fire Geometry LOD.jpg

Test_Tank_01: Fire Geometry LOD

Surface A3\Data_F\Penetration\armour.rvmat provides Rolled Homogenous Armour (RHA) equivalent in Arma world. For best results, create convex components with armour plates offering desired Line of Sight thicknesses. Refer to http://en.wikipedia.org/wiki/Sloped_armour for more details about real life side of the issue.

For example, T-72’s front armour should have protection level of 550mm RHA horizontally. As you can see in example model, the plate itself is much thinner. Due to sloping it can withstand penetration up to 550mm RHA.

If you have small components that otherwise are difficult to model, you can always make use of armour_plate.rvmat (30mm RHA), armour_plate_medium (80mm RHA) and armour_plate_heavy (110mm RHA). Just beware that components using such surface material will NOT stop projectiles after penetration.

You may also need a metalplate component inside free space inside, to catch bullets that otherwise shouldn’t even pass primary armour but for whatever reason (f.e. sticking gun’s muzzle into tank) it’s possible to bypass primary armour.

Hitpoints

Hitpoints represent weak points in structure of tanks: turret servos, ammo storages, engine. They can also improve internal penetration handling.

File:Test Tank 01: Hit Points LOD.jpg

Test_Tank_01: Hit Points LOD

Hitpoint categories

There are 3 common hitpoint categories in Arma 3's tracked vehicles:

• HitHull, handling internal penetration - when damaged over 0.9, vehicle will explode.
• HitEngine, handling damage of engine
• HitLTrack, HitRTrack, damage of tracks/drive sprockets/idlers

Turrets have their own class HitPoints, coontaining info about how easy it is to damage given turret:

• HitTurret, horizontal rotation
• HitGun, vertical rotation - this should handle any event that renders tank guns inoperable, f.e. hit to servos

New attributes

Hitpoints gained two important attributes in Arma 3:

• radius, defining size of “hitpoint sphere” around each vertice in HitPoints LOD assigned to given hitpoint’s selection
• explosionShielding, multiplying damage inflicted by explosive rounds. The smaller it is, the less damage hitpoint will receive.

Internal damage

Internal damage is handled by HitHull class. When KE round penetrates the armor plates, it passes the damage to HitHull hitpoints array as seen in example model. The hitpoint vertices are set up in such way that the nearest distance between them equals RADIUS attribute in HitHull class, and they cannot be activated by rounds that fail to penetrate armor.

File:Test Tank 01: HitHull vertices vs. Fire Geometry LOD.jpg

Test_Tank_01: HitHull vertices vs. Fire Geometry LOD

During implementation of internal damage handling it is important to tweak following attributes:

• armor
• explosionShielding
• radius

If the results of config tweakinng are unsatisfactory, consider adding greater detail to the hitpoints and fire geometry LOD.