Model static fires equalizing with the local atmosphere #32760

IProduceWidgets · 2024-10-12T00:50:28Z

About the PR

Previously, burning things would become very hot, however, and then they might break from taking heat damage. This was about all that happened.

Now, burning things heat up to a maximum temperature, while doing so, they emit heat into the local atmosphere. The local atmosphere can also cool flammable entities, effectively equalizing their temperature over time. This means being near burning things could be a bad idea, it also means you can use burning things to heat a cold room, or a cold room to cool burning things down.

Why / Balance

If you're burning, you're still gonna die, and the damage from actually burning has not changed. The difference is you will no longer become the surface of the sun hot from being briefly on fire. This might lead to less ashings as high temperature (which are very hard to alleviate in game) also cause heat damage. However, although you are not on fire, burning things may still heat up the room, and a hot room may still hurt you.

The big balance change here, is that now the temperature is more realistically simulated, which means, Atmos now needs to pay attention to what the temperature is in different parts of the station. If the only thing contributing to temperature changes is player homeostasis rooms should equalize to ~37C, and no one will likely notice. However, flaming things may be way more dangerous.

Technical details

I changed the logic of how the flammable component handled increasing heat. Previously it was just additive and lead to absurd temperatures approaching - or surpassing - the surface of the sun in a matter of minutes. Now that doesn't happen.

I added a limit to the temperature that a burning entity will increase to. This limit can be changed, and might be a good idea to do so depending on accelerants splashed or other factors, but I leave that as an exercise for the reader.

Part of this was enuring that flammable entities are AtmosExposed.

I also changed how AtmosExposed works to make the temperature of the entity not just be effected by the gas around it, but force them to find an equilibrium by conserving the energy when the atmos tile tries to heat an entity. This might mean that its more likely for atmos tiles to become and stay excited.

Media

Requirements

I have read and am following the Pull Request and Changelog Guidelines.
I have added media to this PR or it does not require an ingame showcase.

Breaking changes

Flammable prototypes may need to have their Temperature and Flammable component setting adjusted to account for heat transfer between them and the local atmosphere.

Changelog

🆑

add: Static fires are now modeled, lighting things on fire in a room will cause it to heat up.

Partmedia · 2024-10-12T03:05:34Z

Please be aware that our pull request guidelines ask that you split up unrelated refactoring changes (e.g. removing [ViewVariables] for unrelated fields) in a separate PR. This makes reviewing your actual PR easier, reduces merge conflicts, and makes it easier to revert if things go wrong.

Partmedia · 2024-10-12T03:08:08Z

In place of RequiresOxygen, perhaps it would generalize better to have an GasMixture? InputGasMix similar to how you define a new GasMixture? EmissiveGasMix. This could help this generalize better to different types of burning things.

Content.Server/Atmos/EntitySystems/FlammableSystem.cs

Resources/Prototypes/Entities/Objects/Misc/candles.yml

Resources/Prototypes/Entities/Objects/Specific/atmos.yml

Content.Server/Atmos/EntitySystems/FlammableSystem.cs

Partmedia · 2024-10-12T17:12:15Z

Stepping back a bit and considering gameplay design issues: What problem does this solve? If it's about finding a way to supply the station with gas that isn't a miner, isn't this like a super beefed gas canister? Now I can see why you want to make burning the candles require a bit more work. But I see two issues here:

Functionally, candles are still pretty much still just less useful canisters (even canisters have pressure limits)
The source of gas (via these candles) is still cargo, which several folks have objected to in the past

daevidos · 2024-10-12T18:01:50Z

Would it be possible to name the candles something realistic? Like real Oxygen candles used in submarines are sodium chlorate that on burning produce oxygen and salt. For nitrogen it could be ammonium nitrate since it thermally decomposes into nitrogen and water.
A different PR could make it be possible for chemistry to produce them in a way similar to plastic (upon mixing proper reagents it pops out of the beaker). I envision medical trying to keep people alive in a situation where station atmos is fucked and chemists can make these oxygen candles to pressurize the medical area and save the day.
The canisters have the unfortunate tendency to be accidentally emptied when people refill their tanks so a constant supply of oxygen filling a room would be a nice alternative to deal with station wide atmos issues.

IProduceWidgets · 2024-10-14T00:34:50Z

Okay, so I got clued into more of this bug with the run away temps when I noticed that the temperatures between the flammable entities and the local atmos weren't equalizing at all. It turns out that AtmosExposed entities were just creating energy and not conserving it with the atmos tile they were on. I addressed that, so although this isn't "superconduction" its... conduction lmao.

Stepping back a bit from the gas candles specifically, and thinking more about what this means for flammable things -- ya know, big ol' fires -- with these changes fires will now be scary not just because you might catch fire, but they can be scary just to be near them.

Partmedia · 2024-10-15T19:00:33Z

Content.Server/Atmos/EntitySystems/AtmosphereSystem.cs

@@ -107,7 +107,7 @@ public override void Update(float frameTime)
        var query = EntityQueryEnumerator<AtmosExposedComponent, TransformComponent>();
        while (query.MoveNext(out var uid, out _, out var transform))
        {
-            var air = GetContainingMixture((uid, transform));
+            var air = GetContainingMixture((uid, transform), false, true);


This would need to be in a separate PR if we make this change. I need to spend some time looking at this and see if exciting the mixture is really needed to get temperature to transfer correctly with AtmosExposed, but this may have significant detrimental performance impacts.

As a nitpick, please name the optional non-default arguments (e.g. GetContainingMixture((uid, transform), excite: true). This makes it a lot more apparent what the argument is, especially if someone is reviewing from a diff/GitHub/anything but Rider.

When I tested it without exciting it did work, but then the room's gas mix could have different temperatures in different tiles that wouldn't change until something else excited the gas in the room.

This would need to be in a separate PR if we make this change.

In the interest of fixing the bug, Ill move the gas emission stuff to another PR, I think for it to work I need burning to have temperature behave reasonably so it makes more sense to start there. I do agree that its kind of soaped into something else in supporting making static fires modeled now.

Content.Server/Atmos/EntitySystems/FlammableSystem.cs

IProduceWidgets · 2024-10-15T20:05:15Z

This is pretty closely related to #319 because it implements temperature as a more interactive atmos mechanic.

Partmedia · 2024-10-15T20:54:01Z

Content.Server/Atmos/EntitySystems/AtmosphereSystem.cs

@@ -107,7 +107,7 @@ public override void Update(float frameTime)
        var query = EntityQueryEnumerator<AtmosExposedComponent, TransformComponent>();
        while (query.MoveNext(out var uid, out _, out var transform))
        {
-            var air = GetContainingMixture((uid, transform));
+            var air = GetContainingMixture((uid, transform), ignoreExposed: false, excite: true);


Default arguments need not be re-specified.

Not all atmos exposed devices necessarily need to be excited. Things only need to be excited if the mixture is changed. So this call should be delayed until it's guaranteed that the mix is changed.

Partmedia · 2024-10-15T20:57:28Z

Content.Server/Atmos/EntitySystems/FlammableSystem.cs

+                            var tempBump = MathF.Sqrt(maxDeltaT * temp.SpecificHeat * physics.Mass) * flammable.FireStacks; //monotonic function, slows as it reaches maxT
+                            _temperatureSystem.ChangeHeat(uid, tempBump, false, temp);


This is a really roundabout way to do _temperatureSystem.ForceChangeTemperature.

I still don't think this is necessarily the right way to do this, because it does not respect energy conservation in terms of energy supplied by the candle.

I looked into this a bit more, if we do this (which is something like was originally there):

It does eventually equalize like we would expect, and so we can output a constant* amount of energy while burning into the room, and as long as something is burning the room will continue to get arbitrarily hotter.
However, as it turns out, most things contain a simply ludicrous amount of energy. irl we're talking like 15,000,000j (15megajoules) per kg of wood. In irl this doesnt turn your fireplace into a nuclear bomb because most of the heat is lost to the sky, but a spacestation is an enclosed box, so it conserves all the energy. This would mean if we used real values almost any fire is immediately ultra-deadly.

Understanding that, I think we have two alternatives.

We can go with a constant joule output, and just make up (much lower than irl) joule quantities for entities to make fires not immediately awful, but rooms will continue to heat if you burn more stuff.

We can do some sort of asymptoting function and have the room reach a maximum temperature based on whatever the burned entity is.

Both solutions seem fine to me, I do think the asymtote would be easier to maintain and harder to abuse.

Yeah, so superconduction is the thing that makes the station not an ideal enclosed box. The built-in "asymptoting function"

Or I guess we can do a hybrid, and have it asymptote with a smaller minimum joule gain.

Well hold on. That might be total joules contained in the entity. So then, ~3hr burn time, we would get something like 1,400j/s Thats still pretty high, but not as high.

Okay sure, lets try it just with no asymptote, and just see how it feels.

Partmedia · 2024-10-15T20:59:23Z

Content.Server/Temperature/Systems/TemperatureSystem.cs

+        ChangeHeat(uid, heat * temperature.AtmosTemperatureTransferEfficiency, temperature: temperature); // move heat to entity
+        _atmosphere.AddHeat(args.GasMixture, -1 * heat * temperature.AtmosTemperatureTransferEfficiency); // remove heat from air


Separate PR, because this is a bug fix to TemperatureSystem.

Its necessary for temp-emitting fires.
Without it, temperatures cant equalize and run away.

Content.Shared/Atmos/GasMixture.cs

Partmedia · 2024-10-15T21:03:43Z

Resources/Prototypes/Entities/Objects/Misc/candles.yml

      firestackFade: -0.01
      damage:
        types:
          Heat: 0.1
+    - type: Temperature
+    - type: AtmosExposed


This does not need to be added here, because you EnsureComp it when it gets lit.

Its not strictly necessary, and probably fine if we drop it, but it does mean that the temperature of flammable things will be wrong when they initially catch fire. Could lead to weird behavior like catching fire initially cooling the room before heating it again.

Why is that?

This would mean that every single candle gets called in the AtmosUpdate event.

They would have whatever the prototype temperature is (usually 20C) until they gain the AtmosExposedComponent and equalize. So if the room is already hot, say 50C, when the candle is lit it will initially be colder than the room and pull heat from the air until it reaches room temp.

Although now I'm saying that, I can probably just fake it by setting the entitie's temperature to the air temp when it first ignites.

Resources/Prototypes/Entities/Objects/Specific/atmos.yml

Partmedia · 2024-10-16T23:44:07Z

Everything said, I think the presently-PR'd heat-addition approach (_temperatureSystem.ChangeHeat(uid, flammable.JoulesPerFirestack * flammable.FireStacks, false, temp);) is the right way to go. Thanks for working on this and your patience while we clean up the last bits.

IProduceWidgets added 3 commits October 11, 2024 06:33

gas candles proof of concept

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gas candles

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cargo stuff

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IProduceWidgets requested a review from Partmedia as a code owner October 12, 2024 00:50

IProduceWidgets changed the title ~~Allow gas to escape frm buring things and add gas emitting candles.~~ Allow gas to escape from burning things and add gas emitting candles. Oct 12, 2024

github-actions bot added the S: Needs Review Status: Requires additional reviews before being fully accepted label Oct 12, 2024

IProduceWidgets added 5 commits October 11, 2024 20:55

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Partmedia added the Changes: Atmospherics Code Changes: Might require knowledge of atmospherics code & calculations. label Oct 12, 2024

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Partmedia self-assigned this Oct 12, 2024

Make flammable things equalize temp with the atmosphere.

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IProduceWidgets added 3 commits October 15, 2024 15:24

Yoink out gas emissions for later PR.

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yoink gas emission stuff p2

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Reviews, and regular candles as debug item.

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IProduceWidgets changed the title ~~Allow gas to escape from burning things and add gas emitting candles.~~ Model static fires equalizing with the local atmosphere Oct 15, 2024

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Model static fires equalizing with the local atmosphere #32760

Model static fires equalizing with the local atmosphere #32760

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		var tempBump = MathF.Sqrt(maxDeltaT * temp.SpecificHeat * physics.Mass) * flammable.FireStacks; //monotonic function, slows as it reaches maxT
		_temperatureSystem.ChangeHeat(uid, tempBump, false, temp);

		ChangeHeat(uid, heat * temperature.AtmosTemperatureTransferEfficiency, temperature: temperature); // move heat to entity
		_atmosphere.AddHeat(args.GasMixture, -1 * heat * temperature.AtmosTemperatureTransferEfficiency); // remove heat from air

Model static fires equalizing with the local atmosphere #32760

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IProduceWidgets commented Oct 12, 2024 • edited Loading

About the PR

Why / Balance

Technical details

Media

Requirements

Breaking changes

Partmedia commented Oct 12, 2024

Partmedia commented Oct 12, 2024

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