Differentiating Between Cover and Concealment

[Surrealistik]

Okay, we all know that destructible terrain is largely eliminated as a possibility due to engine limitations. Unfortunately, the removal of destructible terrain also means that the important tactical difference between cover and concealment has been effectively eliminated.

The solution?

Impliment wall and obstacle penetration.

The underlying system is simple conceptually. Each wall/obstacle would have a certain 'absorption' value. This represents how much damage an obstacle can absorb from a projectile capable of penetration. If the absorption value for a given obstacle is exceeded by a penetration capable projectile, that projectile will travel through the obstacle, and its damage will be diminished by an amount equal to the exceeded absorption value.

Note that not all projectiles are capable of penetration (most plasma based ones for example), and those that are not will not travel through an obstacle regardless of how much that barrier's absorption value is exceeded.

Furthermore, attempting to fire at a target through an obstacle with a soldier that does not have a line of sight to the target will result in signifigant accuracy penalties for obvious reasons. The spread of shots made against targets by a soldier who does not have LoS to them will be increased dramatically (2-4x).

In conclusion, this system promises to substantially increase gameplay depth by introducing differentiation between cover and concealment, which in turn requires players to be much more tactically aware to be optimally effective. Furthermore, this is accomplished without signifigantly, or at the very least infeasibly, increasing consumption of computing resources.

[Sophisanmus]

Varying penetration potentials for different ammunition types would be wonderful.  An AT rocket, for example, could pierce multiple 'soft' buildings, while an HE wouldn't make it through anything remotely sturdy, but its shockwave could rip through targets behind whatever it hits. 

There also needs to be consideration of the distance to the obstacle(s) from the shooter compared to the distance of the target from the shooter.  Attempting to fire through the wall your soldier is crouching behind to hit an alien half the map away should be penalized more than firing at the same distance at an alien behind the wall...

[Surrealistik]

Yes, both are good ideas for refining the penetration system.

The mathematical basis for accuracy loss/spread as defined by distance from a penetrated obstacle might be (250 - Distance) / 125 = Spread Multiplier. I selected 250 as this is the maximum possible range for most weapons, and 125 as the divisor to limit the max/min range to 2-0. This spread multiplier would 'stack' with the base penalty for attempting to shoot at a target you do not have LoS to through an obstacle. For example:

Base spread with an aimed assault rifle shot is 1/1. Trying to shoot an alien through a wall would increase the spread by a factor of 2, to 2/2. Then, because the distance between you and that wall is 4, the spread would be multiplied again by 1.968 ((250 - 4) / 125) to 3.936/3.936. If dynamic spread is possible though, spread should change by a given amount after contact with an obstacle, 2 let's say, if fixed.


As for varying types of ammunition being better able to penetrate, perhaps a set of coefficients could be used to determine the specifics of penetration. For example, a 'power' coefficient of 2 for a round would mean that round has twice its regular power for the purposes of penetration, while an 'efficiency' coefficient of 0.75 for a round would mean that only 75% of an obstacle's absorption value applies for the purposes of reducing that round's damage.

Alternatively, both coefficients might conceivably be merged into one, this singular value determining 'power' for the purposes of penetration, while its inverse determines how much of the absoption value is deducted.

[Sophisanmus]

I prefer the idea of a single coefficient, keep it simple.  If there becomes need of a second value later to tweak certain weapons' behavior, such as something governing explosive penetration or related situations, you will still have one less value stored.

I can see the primary concern for implementing this would be factoring in the varying widths of potential map items, and different values for different textures.  I could see a general formula based on asset thickness and some feature(s) of the object; a simplified version could shore up older maps that are not designed with this consideration.

The biggest concern I have right now of what could go wrong with this idea would be HE/IC/other explosive/spread munitions.  The HE rocket, for instance, should do 100% of the appropriate damage to those caught in the blast regardless of how many windows it has gone through along the way.  I don't know if explosive weapons have separate values for their primary and splash damages; if so, this point may be moot.

[Lord Valdez]

So it is an engine limitation. Pity. I really miss it. It was a real fun to demolish buildings
I agree that penetration system mitigates the problem.
Rockets are big and slow objects compared to bullets, so they shouldn't have good penetration properties and the explosion is triggered by contact.
I imagine that blasts should have good penetration, especially HE types, while IC shouldn't be so good.
Armor-piercing ammunition obviously should have good piercing ability, because they can maintain the movement energy.
In similar logic, flechettes are heavy and hard, they should be able to punch through a thin wall, while shrapnel not, because the energy is distributed between the particles.
So I basically agree.

[Sophisanmus]

Now, if there was a way to perform some limited environmental reduction (someone mentioned some "bubble" thing), it could be applied only to certain, sufficiently powerful/explosive weapons, such as HE rockets.  Now, anti-tank rounds, which I'm hoping will appear once needed, would have more of a penetration effect.  Grenades can probably be excluded, fragmentations probably won't have the house-busting effects like the original X-COMs...

[Telok]

Penetration values for terrain and weapons is a nice compromise between the mapping engine limitations and players lust for property damage. As a bonus it will also make limited use weapons like bolters and particle cannons more attractive is support roles, particularly combined with the IR goggles limited ability to see through walls. I think the accuracy issue can be addressed by simply adding a decent "to-hit" penalty to targets that the soldier does not have a valid LoS to. Multiplying the normal accuracy by .35 to .15 depending on fire mode or skill used would probably work as a starting point, it should be easy to code too.

My biggest concern is whether or not the mapping engine can be modified for this (probably true) and what it will do to existing maps. Every object on every map will have to have this new value added to it, that's going to take time and effort. A possible alternative could be to assign the penetration value for objects to the textures used in the maps. This way we would end up with stone, metal, cardboard, etc. textures with their own penetration values. Added bonus here would be portability between maps and a more consistent set of values across all the maps.

It is a good idea.

[Mayhem]

The biggest snag I can see is the Alien AI.

If shooting through walls is possible, it should be possible for everyone.

The aliens already clairvoyantly know exactly where your men are.  If hiding behind a wall becomes no defence against a particle rifle, things are going to get rather difficult for us poor beleagured earthmen.

[Surrealistik]

Yeah, the alien AI would need revision such that it isn't always infallibly aware of your troop's positions, but from what I understand, that fix is well on its way, and should be implimented soon.

[JerryLove]

The simplest mechanic I can think off.

Add a single variable to a weapon/ammo that represents "penetration".
When weapons fire hits a barrier, the penetration is compared to the barrier's hardness.

X = hardness / penetration

The (initial) damage and range of that shot are now multiplied by X. (if that lowers the damage below zero or range below how far the fire has already traveled, it stops).

I say "initial", because it's additive. If I shoot a bullet with a penetration in a line that goes through two walls with a resistance of 4, it should loose half it's damage/range at the first wall and the other half at the second (as opposed to half of the remainder).

This is better than simply using the damage value alone as it allows some weapons to be better at penetrating barriers than others. Interestingly, armor could also be considered a barrier. It's not perfect, but I propose that it offers a good balance of simplicity, "realism" and flexability.

[Destructavator]

Penetration is affected by the ammunition type - I recall from my last job in the law enforcement area that some officers had different ammunition in the magazines of the handguns they carried on duty, and sometimes bullets that had less penetration were favored because of situations where if they had to shoot someone they didn't want a bullet to go straight through a suspect and keep going.

On the other hand, fighting aliens with military weapons of the future is of course a different situation.

If penetration was implemented with some rules, the coilgun could very well become even more cool - I can envision shooting several aliens lined up in a tight corridor and taking them all down with one shot, or if a spotter sees an alien near a wall, a soldier with a coilgun could perhaps shoot through the wall and take down the alien.

Then again, I don't know exactly how the coilgun works or much about the technology it's based upon, last time I checked there was no UFOPedia text for it (yet).

One barrier that definitely needs things to pass through IMO is the fences in farm maps, it's bad enough soldiers can't really see through them, but when aliens are spotted on the other side they can't be shot through the gaps as the fences are treated as walls.

[Surrealistik]

Penetration is affected by the ammunition type - I recall from my last job in the law enforcement area that some officers had different ammunition in the magazines of the handguns they carried on duty, and sometimes bullets that had less penetration were favored because of situations where if they had to shoot someone they didn't want a bullet to go straight through a suspect and keep going.

Yes. Currently this kind of penetration discrepancy is crudely implimented in differences between certain munition types such as slugs and flechettes, as well as damage subtypes (normal damage for example, is divided into light/medium/heavy/etc...). In any case, different munitions should certainly feature differing powers of penetration, at least for the purposes of penetrating walls/terrain. Anyways, that all said, it is certainly possible for a penetration system to use the existing armour/damage mechanics, and perform with reasonable plausibility, with walls effectively having 'armour' that determines the penetrative effectiveness of differing damage sources and weapons.

Then again, I don't know exactly how the coilgun works or much about the technology it's based upon, last time I checked there was no UFOPedia text for it (yet).

It's another form of electromagnetic propulsion technology that utilizes literal charged coils (or circles) rather than rails, to accelerate a projectile.

One barrier that definitely needs things to pass through IMO is the fences in farm maps, it's bad enough soldiers can't really see through them, but when aliens are spotted on the other side they can't be shot through the gaps as the fences are treated as walls.

I completely agree. Apparently this is being rectified though.

[JerryLove]

Anyways, that all said, it is certainly possible for a penetration system to use the existing armour/damage mechanics, and perform with reasonable plausibility, with walls effectively having 'armour' that determines the penetrative effectiveness of differing damage sources and weapons.

So the existing system would allow for a jacketed round to do less base damage than a blossoming round while maintaining the same damage type, and yet be more capable of penetrating barriers?

You had seemed to indicate earlier that simply using the damage/type information would end up requiring exception coding.

[Surrealistik]

So the existing system would allow for a jacketed round to do less base damage than a blossoming round while maintaining the same damage type, and yet be more capable of penetrating barriers?

Yes, due to damage subtypes. For example, soft rounds less adept at armour penetration might be classified as 'normal_light', while harder, penetrating ones would be 'normal_heavy'. These subtypes determine how the rounds interact with armour, and more specifically, the extent of a given armour's damage reduction. Typically, armour deducts more damage from subtypes classified as 'light'.

You had seemed to indicate earlier that simply using the damage/type information would end up requiring exception coding.

Are you sure you aren't confusing this with my statements concerning the game's engine limitations? Adapting the AI to take advantage of this new feature without exploiting it might require signifigant additional coding.

[Sophisanmus]

I'm a proponent of using a new value for penetration rating, as opposed to calculating it from some factor of ammunition damage intensity and type.  Calculating it from the existing stats on-the-fly not only demands the assignment of additional values to the damage types, but the result of the calculations will still need to be stored or re-calculated at every firing.  All in all, it demands more processing and more resources, while offering the weapon tweaker less control over the behavior of the projectile. 

In terms of terrain "armor", a single value may be enough.  We can simply handle penetration as a single concept, and thus need only one value from each participant.  We don't need to factor damage types here, as the terrain will not be degrading; the only considerations are whether the projectile passes through, and, if so, how much it is diminished in the process.