DropTeam Engine Details

TECHNICAL DETAILS ON THE SIMULATION ENGINE BEHIND TBG’S REAL-TIME COMBAT SIMULATOR

PHYSICAL OBJECTS

All tangible objects in the game are called “PhysicalObjects.” This includes anything that plays a role in the game’s physical simulation. For example, vehicles, rocks, trees, projectiles, and buildings are all PhysicalObjects. Some examples of objects in the game world that are not PhysicalObjects include puffs of smoke and small pieces of debris that litter the ground. These are not PhysicalObjects because they do not play a direct role in the physical simulation.

PhysicalObjects are hierarchical. A PhysicalObject may have any number of other PhysicalObjects attached to it as children, and in turn those children may have their own children. A PhysicalObject is attached to another PhysicalObject via a “joint”, which constrains the relative positions of the two objects. The following types of joints are modeled:

Hinge joints

Ball and Socket joints

Slider joints

Suspension/Steering joints

For example, the chassis of a wheeled vehicle might have 5 children: 4 wheels and a turret. The wheels would be attached to the chassis via Suspension/Steering joints and the turret would be attached to the chassis via a hinge joint. The turret might have a single child of its own: a gun attached to the turret by a hinge joint. In this example, there are 6 PhysicalObjects comprising a single vehicle.

PhysicalObjects have hundreds of properties, but the most important ones are:

Mass and Moment of Inertia.

Total Armor Density – regardless of the actual material that comprises the object, this value is in the unit of measure of “millimeters of steel” – it tells us the equivalent number of millimeters of steel that an object’s skin provides. A 3D map of these armor thicknesses is supplied for each PhysicalObject (allowing them, for example, to have more armor on their “front” than on their “sides” and “rear.”)

A listing of InternalComponents, as described below.

Coefficient of friction for contact with ground and other objects.

3D map of the object’s surface to be used for projectile collisions and penetration.

INTERNAL COMPONENTS

PhysicalObjects may contain any number of embedded items called “InternalComponents.” These are items of interest that reside inside of the PhysicalObject, such as engines, ballistic computers, gunners, drivers, fuel tanks, ammo magazines, etc. When these items are inside of a PhysicalComponent and are functioning correctly, they imbue the PhysicalObject with capabilities that it wouldn’t otherwise have. For example, a ballistic computer inside of a turret allows the turret to automatically calculate trajectories for its guns. If the ballistic computer is destroyed, then the turret loses this capability.

InternalComponents have an actual position and size within the PhysicalObject that they are within, a rating of the component’s “toughness” and tendency (if any) to burn or explode when hit by a projectile, and certain properties related to its GUI display for a user who may be in control of the PhysicalObject containing that component.

To view some vehicle internal component schematics, click here!

PROJECTILE PENETRATION AND DAMAGE

When a projectile strikes a PhysicalObject, the engine first calculates whether or not the projectile is able to penetrate the object’s armor. If the projectile isn’t able to penetrate, then it will either ricochet off of the armor (potentially hitting something else afterward) or it will explode, depending on the type of projectile. If it does penetrate, the effect of the penetration is modeled in detail.

The decision about whether or not a projectile penetrates is based on 3 factors: the projectile’s penetrating power, the thickness of the armor being penetrated, and the angle at which the projectile has struck the armor, each of which is covered below.

PENETRATING POWER

There are 3 types of projectiles modeled by the engine: high velocity armor piercing slugs (AP), high explosive anti-tank (HEAT), and high explosive (HE.) Artillery and mortars combine multiple projectile types in one attack (their blast is modeled as HE and their fragmentation is modeled as a high number of small AP projectiles.) Each type of projectile has its own means of penetrating armor.

AP projectiles have a penetrating power that is dependent on the projectile’s velocity. These munitions are simply dense, heavy slugs that use kinetic energy to kill their targets. The projectiles have high penetrating power at short range, but gradually lose penetrating power as they fly through atmosphere because air drag slows them down during flight. Their penetrating power is therefore highly dependent on the atmospheric density of the scenario being played. With little or no atmosphere, AP rounds can kill at extreme ranges. In high density atmospheres, however, these projectiles lose penetrating power very quickly.

In contrast, HEAT and HE projectiles have fixed penetrating power that doesn’t change over distance. These types of projectile derive their penetrating power from explosive warheads. HEAT rounds are shaped charge warheads that spray hot plasma in a forward-facing cone when they explode. This configuration is ideal for penetrating as much armor as possible but severely limits the warhead’s area effect. HE rounds rely on concussion and fragmentation to cause damage in a wide area, though it has little chance of ever penetrating well armored targets, even in the case of a direct hit. Both HEAT and AP rounds are generally less accurate than AP simply because they fire at much lower velocities.

In summary, AP rounds have the highest penetrating power, at least at short ranges. Depending on the scenario’s atmospheric density, at some range HEAT rounds will become more effective than AP. HE rounds are best used against soft or scattered targets.

ARMOR THICKNESS AND ANGLE

The penetrating power of a projectile must be greater than the Effective Armor Thickness of the target in order to penetrate its armor. The Effective Armor Thickness is determined by the actual thickness of the target’s armor at the impact point and also by the angle at which the projectile is striking that armor.

If a projectile hits a slanted surface, then it must penetrate more armor than if it had surface at a perpendicular angle. Therefore, the more “sloped” the impact point is on the target, the higher the Effective Armor Thickness will be.

These calculations of penetration normals by projectiles against armor are done on the literal triangles that you see rendered for the unit itself. Therefore, that nice sloped glacis on the front of the Paladin really does help it survive. When you're shooting at a Paladin, you might see your shots bouncing off of its glacis up into the air, but if you lower your aim a little to the flatter area under the glacis, you might find that those same projectiles are now penetrating and doing damage. This is because you're hitting the armor at a more perpendicular angle, so you have less armor to penetrate.

EFFECTS OF PENETRATION

When a projectile penetrates a unit's armor, the simulation actually traces its path through the interior of the PhysicalObject to see which, if any, InternalComponents are hit by the projectile. Every InternalComponent has a "Toughness Factor" and projectiles have their own "Direct Kill Factor" (this value is different for each type of projectile.) These values together decide if the projectile damages, kills, or fails to significantly harm an InternalComponent that it hits.

In addition to this kind of direct kill, projectiles which penetrate also cause fragmentation damage. Each type of projectile has a "Fragmentation Factor." This factor combined with the amount of armor that was penetrated determines how much fragmentation is caused by the projectile's entrance into the interior of the unit. Fragmentation will usually only damage the squishy InternalComponents, such as drivers and gunners. It can damage InternalComponents that are not directly in the projectile's flight path (but they still need to be relatively close to the flight path.)

Each InternalComponent and each type of projectile also have their own "Burn Factors." For example, fuel and ammo magazines have high burn factors, engines have a very low one, and most other components have zero. Based on the burn factor of the projectile and the InternalComponent being hit, there is a chance that the unit will be ignited and burn, and a smaller chance that the unit will catastrophically explode.

Also, AP projectiles with extremely high velocity have their own chance of igniting a PhysicalObject that they penetrate due to kinetic friction. This ignites the unit regardless of which InternalComponents are hit.

ION BEAM WEAPONS

Ion beam weapons use a particle accelerator to speed up heavy ions to a sizeable fraction of the speed of light and then hurl them at a target. The resultant energy transfer heats the target up enough to vaporize metal. In practice against armored targets, this means that one must steadily hit the target in the same area, ablating away layers of armor by vaporizing it, digging into the armor until the beam is able to reach into the interior of the target. At this point hits on the target will be totally catastrophic - you're now pumping millions of charged ions at astronomical speed into the interior of the vehicle where transferred energy is unable to escape effectively from the inside of the hull. The target generally blows up and at least suffers greatly.

This means that ion beams, unlike normal projectiles, deal lasting damage to a target on each hit (even hits which don’t penetrate) because it ablates away some of the target’s armor in the area that was hit. Future hits in that area, even by conventional projectiles, will have less armor to stop penetration. Contrast this with conventional projectiles where, if the projectile fails to penetrate the target, no lasting damage is done.