Today we’re going to talk about combat geometry with our resident Sins designer, Conor Harris.

The basic combat model of Sins of a Solar Empire II is held up on two primary pillars: The first is an obvious one - mathematical interactions between weapons and defenses. The second is the physics simulation - a more complex topic we will be discussing in detail today.

The physics side of balance is most relevant to corvettes, strike craft and missiles, although it does extend upwards to bigger ships too. Today we’ll be focusing more on how weapons hit corvettes engaging in their signature orbit-strafe attack pattern.

To begin with, an obvious but important statement:

Easy to understand, not always easy to do when the target won't sit still. There are two types of direct fire weapons in Sins II:

• Fixed Weapons: Sometimes also called ‘spinal’ weapons, they are built into the hull of a ship, usually pointing forward. These weapons must be aimed by maneuvering the entire ship to point at the target.
  
• Turreted Weapons: Mounted in an independently tracking turret that can bring the weapon to bear on the target independently of the facing of the ship it is attached to.

The Cobalt Light Frigate and Kalev Gauss Frigate are good examples of ships with Fixed weapons. Some of the Marza’s weapons are also fixed.

Turreted weapons do not just snap to their target in Sins II, instead rotating at a speed defined by their Tracking Rate stat. A higher tracking rate means a turret is more likely to be able to keep firing at a single moving target, with lighter weapons having better tracking rates compared to large, heavy turrets.

Fixed weapons, as mentioned earlier, require pointing the entire ship to aim - which means they functionally use the turn rate of the ship they are mounted on as a substitute for tracking rate. Most ships turn far slower than a turret, which means fixed weapons on large ships can be difficult to use against moving targets.

Meanwhile, the Harcka Heavy Cruiser and Kol Battleship are excellent demonstrations of turreted weapons.

Thanks to some complicated math, it’s not just tracking rate that defines whether a turret can point at a moving target - range to target also matters a great deal. The further away a target is, the less it is moving relative to a turret’s frame of reference, while a very close target moving laterally to the turret might be able to outrun even the most extreme of tracking rates simply by its proximity. Think of how you can look at a jetliner far above you in the sky and barely move your head to follow its path across the sky, but a fly buzzing around you can be hard to keep looking at even though it is moving much slower than a speeding aircraft.

This principle is replicated in Sins II, where fast moving units at long range can be easily tracked by even slow turning Gauss Cannon turrets, but a corvette speeding past a ship at point blank range will evade even a high tracking PD Autocannon, at least until it gains some distance again.

In practical terms, this makes a single corvette nearly immune to attack from a slow tracking turret like a Gauss Cannon or a slow maneuvering ship with fixed weapons like a Kalev - as long as it is engaged in its orbital-strafe attack.

However, there are two other factors that complicate Sins II physics-based gameplay as it applies to turrets and corvettes.

First, a weapon only really needs to be pointing at a target in the moment that it reloads. This is because it doesn’t really matter if a weapon currently in a reload cycle is pointing at a target or not - it can’t fire anyway… it’s reloading.

Second, Sins II isn’t a game about honorable one on one ship duels, it's a game about huge fleet battles featuring hundreds or thousands of ships. One corvette orbit-strafing around a ship might be in an excellent position to evade most of its attacks, but one hundred corvettes orbiting the same target form a giant spherical cloud of targets.

The practical result of these two factors is that weapons with slow tracking rates aren’t really prevented from doing nearly full DPS in a large-scale battle, as even if their preferred target isn’t in their sights, something worth firing on will be. Meanwhile slow reload rates can actually be a good thing for such weapons, as even in smaller battles it won’t matter how badly a target is being tracked if the gun is busy reloading; and there is a good chance something will be at least near the direction the gun is pointing by the time it is reloaded.

We can’t possibly miss them!

Of course, while large battles tend to partially negate tracking of targets in terms of achieving full DPS, slow tracking weapons will still struggle to focus their damage output on a single target. This is important for corvettes when fielded in number. A swarm of corvettes may be a target rich environment, but the damage they take will also tend to be distributed between the many ships in the swarm, giving the whole force a degree of longevity beyond what the tiny hit point pools of the individual ships would suggest.

Because of this, repair abilities, especially area of effect repair, go a long way in keeping a corvette swarm operational - even if the repair rate per ship is quite low. Intrinsic regeneration, such as Shield Burst or the in-combat regeneration accessed by the Vasari also has an outsized effect on keeping corvettes alive.

On the other side of things, slowing down a moving target with abilities that impact speed cannot just make it easier for heavier weapons to hit a target, but crucially makes it easier to focus single targets to complete destruction. Equally, increasing turret tracking rate or ship turn rate can similarly enable more focus fire and therefore secure more kills.

For people modding their own factions into Sins II, there are some important takeaways for balance if you want your turrets to have a meaningful impact on gameplay.

• Tracking rate is not the name of the stat in the .weapon file - “pitch_speed” and “yaw_speed” are the two stats that I have been referring to as tracking rate for purposes of this article.
  
• The faster a weapon reloads the more tracking rate matters for sustaining maximum DPS against a moving target.
  
• The longer the range, the less tracking rate is needed to keep a weapon pointed at a moving target.
  
• Ships using an Orbit attack pattern actually benefit from shorter range, as the closer they are to the target the more tracking / turn rate is needed to keep them targeted.
  
• Tracking rate can usually be quite low and still stay on target.
  
• Tracking rate buffs are always relevant for bringing a weapon on to a new target faster, thereby wasting less firing time.

In the next Combat Geometry dev diary, we’ll dive into the complexity of Missile and Point Defense balance, building on the principles outlined today to explain why your capital ships always die to Kanrak Assailants (and maybe how to avoid that)!