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Ideas

General ideas for damage model mechanics. Not necessarily good ideas!

Impact Weapon Types​

  • Proximity Trigger (e.g. RPF flak)
    • On detonation, does damage in a cone along velocity vector.
      • AOE damage
      • Spawn lots of rays and test each
    • When the game detects that the bullet has hit the target, spawn explosive VFX back along the approach vector
      • May need a modification to bullet rendering
        • Or a modification to collision system, to do fat raycast
  • Contact Explosive Trigger
    • On impact:
      • If shell shatters, apply kinetic damage
      • If intact, apply blast and fragmentation damage
  • Armour Penetrating
    • On impact:
      • Compute penetration based on shell/armour characteristics and impact properties (angle, speed)
      • If it penetrates:
        • Trace line through internal colliders, applying the same logic
        • If there's a timed/delayed fuse, detonate that at the right time (depth / speed = fuse time)
      • If it fails to penetrate:
        • Ricochet or shatter

Examples​

RPF Flak Shell​

  • No direct penetration - damage is limited to the surface only
  • Fat raycast ahead of the actual bullet location, radius is the proximity distance
  • When collision is detected:
    • Spawn VFX back at the bullet location
    • Apply damage within a cone, probability of hit based on fragmentation density, range and angle
    • Each hit generates a small kinetic impact, minor armour damage
      • Pitting on thick armour, possible penetration on thin armour
      • Damage to antennas/sensors/other exposed equipment

Contact High Explosive​

  • When the shell hits, trigger an explosion at the surface (see explosive damage type below)
    • Explosion falls off with distance. Deformation, spalling, breaking a hole all possible.
    • Shrapnel shards fly off at explosive speed, do not slow down with distance.

Armour Penetrating​

  • When a shell hits, calculate penetration results:
    • Shatters, apply minor kinetic damage
    • Fails to penetrate, explodes on surface (see contact explosive)
    • Penetrates, reduce energy of shell and repeat on next layer down
      • After some time, trigger an internal explosion (assuming the shell has a warhead)

Damage Types​

Weapons can apply one or more of the following damage types:

  • Kinetic
    • Surface cratering (weaken for future hits)
    • Penetration, repeat call on next layer
  • Explosive
    • Shockwave dissipates very rapidly in vacuum
      • If pressure exceeds yield strength, deform
      • If this exceeds some spalling threshold, do damage internally
      • If it exceeds some destruction threshold punch a hole, repeat on the next layer
    • Explosive fragments do not slow down, can cause kinetic damage at range
    • Shaped explosives are a thing, feels like an entirely different damage type
  • Thermal

Penetration Equations​

DeMarre Equation​

Calculates penetration depth of a shell, based on known penetration for another similar shell. Could be used to interpolate between pre-calculated penetration depths (e.g. do expensive depth calculations in ship editor). Ref: https://www.tankarchives.com/2014/10/penetration-equations.html

P=Ref(P)∗(V/Ref(V))1.4283∗(D/Ref(D))1.0714∗(W/D)0.7143(Ref(W)/Ref(D))0.7143P = \frac{Ref(P) * (V / Ref(V))^{1.4283} * (D/Ref(D))^{1.0714} * (W/D)^{0.7143}}{(Ref(W) / Ref(D))^{0.7143}} Where Ref(X) means the value of X for some known reference.

  • P: Thickness of armour that a shell will penetrate.
  • V: Velocity
  • D: Diameter
  • W: Weight

Krupp Formula​

Estimates penetration depth for battleship armour. If a good K value can be calculated (e.g. offline through testing, or just as a material parameter) this could be useful. Ref: https://www.tankarchives.com/2014/10/penetration-equations.html

B=V∗PK∗DB = \frac{V * \sqrt{P}}{K * \sqrt{D}}

  • B: Depth of penetration (in decimeters)
  • V: Velocity
  • P: Mass
  • K: Armour resistance constant, default to 2400.

Lanz Odermatt Equation​

Calculates penetration depth of a long-rod penetrator, used for modern tank shells. Ref: https://www.longrods.ch/perfeq.php