How can I improve this gunner's defenses?

[Thom Blair III]

I have gunner stations at my main gates (see picture). I'd like to give them the best defenses possible. So far, here is what I've come up with:
- granite walls & gates for durabililty/flameproofing
- flagstone for flameproofing
- lots of firefoam poppers to protect from incendiary rounds (I've had a lot of those recently)
- one row of sandbags
- 3 lights for seeing attackers
- improvised turrets are far enough away from gunners that they won't hurt colonists when they explode (I can easily afford to replace them)

Things I'm wondering about:
- would more sandbags help? I just read sandbags can protect turrets...is that true?
- do multiple rows of sandbags provide more cover?
- I read in the wiki having lights near my gunners is bad...it should be dark there and bright where the attackers are. Is this still true?

[attachment deleted due to age]

[Yoshida Keiji]

I think you missed the Guide: https://rimworldwiki.com/wiki/Defense_structures

From that picture:

* You don't need that many foam poppers, in any case have one per pop bubble, as long as the foam is spread across the ground nothing will burn, except for if it rains and the water washes it off. So if you are scared of the Inferno Cannons, activate them before the battle starts, but only when you are sure were the battle will take place.

* I personally use turrets as support or last line of defense, not as front line.

* I don't use lights outside. They will probably get destroyed first, wasting your resources.

* Sandbags CAN protect turrets, yes. It is true that more are better but makes it hard to cross if it is a door you frequently use. Unless you have another access point.

[Thom Blair III]

Thanks! I hadn't seen that guide. That looks like a lot of good stuff. I also didn't realize the firefoam residue was flame retardant once on the ground...that's really good to know.

I'm interested in how much an extra layer of sandbags helps...do you have any data on how much more protection each layer adds? Does it max out at some point?

[EvadableMoxie]

I'm interested in how much an extra layer of sandbags helps...do you have any data on how much more protection each layer adds? Does it max out at some point?

You can check by putting a colonist into position, drafting them, then scrolling over the turret. It'll tell you the chance to hit and cover bonuses, so you can experiment with different set ups and see what works.  That said, I am fairly certain an extra layer of sandbags won't give an additional cover bonus, though it would slow down advancing melee.

[Thom Blair III]

You can check by putting a colonist into position, drafting them, then scrolling over the turret. It'll tell you the chance to hit and cover bonuses, so you can experiment with different set ups and see what works.

OH, that's awesome! I didn't know you could do that. Thanks!!

[Thom Blair III]

It'll tell you the chance to hit and cover bonuses

Actually, what is that feature/mouseover box called? I'd like to study it since I don't understand what each number means. I'm guessing:
- 550/550 - that's the hitpoints left on the turret
- Shot by Merandil: 48% - I don't understand this one...he's manning the turret and there are no attackers, so what is the percentage representing? Maybe it's the percentage of clear shots he has, since there are those 3 improvised turrets blocking some of his shots (shown in the first picture)
- Shooter 98% - is this how covered he is or how clear of a shot he has at attackers?
- Weapon 80% - is this saying the turret has 80% cover?
- Target size 68% - I don't understand this one
- Cover 90% - I'm guessing this means Merandil has 90% cover?

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[EvadableMoxie]

Shot by: Is the final percentage.  In this case, a 48% chance to hit.

Shooter is the contribution based on the shooter's skill and physical abilities.  In this case, a 98% chance.

Then modifiers come into play. You multiply the modifiers by your base chance.

Weapon is the contribution based on the weapon being used.  In this case, a 80% chance
Target size is the chance to hit bonus or penalty based on the size of the target.  In this case, 68%.
Cover is the chance based on the amount of cover.  In this case, a 90% chance.

So .98 x .80 x .68 x .90 = 0.479808 or a 48% chance to hit.

Keep in mind this is based of where your pawn is standing, so if you want to know the chance an attacker would actually have, you want to move them to where the attacker would be, rather than checking the stats from right next to the turret.

[fritzgryphon]

Cover is only considered for directly adjacent cells.  For example, the mini-turret in the bottom left gains no cover from those sandbags.

[Thom Blair III]

Thank you very much for the breakdown! Now it makes a lot more sense. One part I'm not clear on is the Target Size since there was no target selected and there were no enemies anywhere on the map. So, where does that data come from? Maybe it's just inaccurate/filler data until an actual target is selected?

Keep in mind this is based of where your pawn is standing, so if you want to know the chance an attacker would actually have, you want to move them to where the attacker would be, rather than checking the stats from right next to the turret.

Cover is only considered for directly adjacent cells.  For example, the mini-turret in the bottom left gains no cover from those sandbags.

These two things make me think it could be very useful to have a cover calculator similar to Environment Display that will tell you the cover for any point you mouseover. Something like in the attached picture. That way you could try new defenses easily and see how well they work without live testing them. Do you think that'd be a good feature or is there a mod that already does this?

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[fritzgryphon]

The accuracy values shown are for Merandil firing at the turret that you're hovering the mouse over.  His base accuracy is 98% (from shooting skill, manipulation and eyesight), the rifle is 80% accurate (at that distance), the target is 68% as big as a person, and the firefoam popper he's standing on is counting as 10% worth of cover by being adjacent to the target(normally a popper blocks 30%, but it's reduced because Merandil is right on top of it).

98% x 80% x 68% x 90% for a chance to hit of 48%.

[Thom Blair III]

The accuracy values shown are for Merandil firing at the turret that you're hovering the mouse over. 
98% x 80% x 68% x 90% for a chance to hit of 48%.

omg! I thought it was his chance for shooting WITH the turret, not shooting the turret itself! XD
And he's only got a 48% chance of shooting the turret he's manning?? No more stoneleaf for him! XD That is crazy.

[Thom Blair III]

Cover is only considered for directly adjacent cells.  For example, the mini-turret in the bottom left gains no cover from those sandbags.

Wait a second...does this mean someone manning the turret must have sandbags directly next to the manning cell? Mine didn't (see picture), so I'd have to add in some right around the cell?

[attachment deleted due to age]

[fritzgryphon]

Right.  If those two turrets are manned from the south, the operators would not have a cover modifier.

It's possible that the turrets themselves might intercept bullets passing through them, like workbenches or solar panels, but I'm not sure how the mod works.

e. the left turret operator would have one sandbag worth of cover, from attacks from the left, only.

[MoronicCinamun]

I am 99% certain that lighting no longer affects accuracy in current versions, was scrapped some version ago because of the exploit of just "haha let's just make a roof and have no lights in our bunker".
It certainly doesn't show up on the shot-percentage tooltip anymore.

[erdrik]

Cover is only considered for directly adjacent cells.  For example, the mini-turret in the bottom left gains no cover from those sandbags.

Wait a second...does this mean someone manning the turret must have sandbags directly next to the manning cell? Mine didn't (see picture), so I'd have to add in some right around the cell?

There is a difference between "cover bonus" and what Ive decided to call "obstruction chance"(since I don't know what it is actually called).
As I understand it:

• As mentioned, Cover Bonus is only applied to defenders that are directly adjacent to the cover, and the bonus is applied against the attackers Accuracy before the shot is fired.
• But Obstruction Chance, is the chance that a projectile will be stopped by a building it is traveling "over", after the Attacker has fired but before the projectile has actually finished traveling. Obstruction Chance will not be shown when you draft scroll over a target.

I believe multiple layers of sandbags, while not adding to Cover Bonus, does add to Obstruction Chance since there are more "buildings" the projectile has to pass to get to the target. Though, I admit I have not tested this under controlled conditions.