[CR]Add night vision from perception, fix flashlight exploit

[Coolthulhu]

Night vision was bugged: the formulas used were calculated using wrong constants and also included rounding where none was expected.
The formulas had comments indicating expected ranges, meaning that author probably expected to keep the old (pre light rework) ranges, like 2 tiles for night vision.

New values are expressed through a clean function that takes expected range as argument and use the correct constants.

The ranges in total darkness are currently ([CR]):

• Base is 1 + (perception / 3) - (eye encumbrance / 10)
• Low night vision adds 2
• Medium night vision (upgraded, ursine, feline or elf) adds 4.5
• Full night vision (full, upgraded elf, cephalophod or nv goggles) adds 10
• Avian eye adds 1
• Low cap of 1

Night vision traits don't stack - best one applies. Avian eye stacks with everything except low cap.

You can still easily wear sunglasses even if your vision isn't augmented, but if you have "round" (to nearest multiple of 3) perception and no other encumbrance, that will be noticeable in total darkness.

The range here is a radius, meaning it scales really well and NV trait will help both the low perception characters who want to avoid tripping over everything and high perception ones who want to see everything during night raids.

So, for example:

Character	NV range
9 per + NV	6
8 per	3
20 per + full NV	20
10 per + goggles	9
4 per + ursine + ballistic glasses	6

Flashlight exploit is when you apply flashlight twice in the same turn to see without being seen. This is fixed by adding a "lit up" effect if your inventory provides more light than some low constant and also more than the ambient light. The effect in turn low caps your light by that low constant for the rest of the turn.

[mugling]

Overall these numbers look too generous, especially those from PER. I can see why you want to keep the scalar low to maintain granularity so it might be worth adding a lower bound so that the bonus is 1 in 2 above PER 8?

[Coolthulhu]

Overall these numbers look too generous, especially those from PER.

I'm trying to keep it conservative with the current generous numbers so that it doesn't result in going back to old (pre-rework) ones. What would be good numbers?

Current master has 1 for no NV trait and 6 or so with it.

adding a lower bound so that the bonus is 1 in 2 above PER 8

I'd rather avoid thresholds like that. They encourage dumping stats and create breakpoints, while also removing rewards for bumping stats from "bad" to "mediocre".

[mugling]

I see your point about breakpoints but the problem is a typical player (PER 10) now has fairly good out-of-box night vision of 4 tiles. You could drop the base 1 tile but retain the lower bound?

[mugling]

It's crude but I can't think of a better solution?

[Coolthulhu]

The worst part is that it is in the vision code.
The problem is, there is no callback like "on player's luminance changed", since luminance is recalculated once per turn and involves effects, items and bionics.

[mugling]

For an existing save if I reduced PER to 0 without other mutations I get a 1 tile radius (correct). Increasing PER sequentially gives no effect until PER 10 or above?

[mugling]

Lit-up effect works correctly though

[Coolthulhu]

Increasing PER sequentially gives no effect until PER 10 or above?

Eye encumbrance?
Are you in total darkness? Partial light will blind NV at a different rate than it grants regular vision. The numbers were never balanced against each other, so little light can be worse than no light.

[mugling]

Zero encumbrance, pitch black (basement)

[Coolthulhu]

Try debugging in NV and then removing it. It sometimes fails to update for some reason.

[mugling]

No change

[mugling]

Should that not be

float range = get_per() / 3.0f - encumb( bp_eyes ) / 10.0f;

[Coolthulhu]

Should probably be.

But that still doesn't explain the 10 per thing.

Is 10 the threshold or just the first value tested that worked?

[mugling]

If you adjust it to 3.0f you get a lower bound of PER 6 for the first increase to two tiles (which makes sense considering you get one point at PER 3 but this is masked by the default lower bound)

[Coolthulhu]

Shit, I'll need to look into it.

Is the rest working fine?