Re-adds and reworks fusion. (#37384)

add: Fusion is back
add: Fusion now happens with large quantities of hot plasma and CO2, consuming all the plasma rapidly and producing large amounts of energy. Other gases can also effect the performance of the reaction.
add: Fusion now produces radiation. Be careful around reactors.
fix: fixes fusion dividing by zero and destroying everything
code: Gas reactions now have access to where they are occurring
fix: Prevents some other reactions from producing matter from nothing

code/__DEFINES/atmospherics.dm

@@ -9,7 +9,7 @@
 #define META_GAS_OVERLAY		4
 #define META_GAS_DANGER			5
 #define META_GAS_ID				6
-
+#define META_GAS_FUSION_POWER   7
 //ATMOS
 //stuff you should probably leave well alone!
 #define R_IDEAL_GAS_EQUATION	8.31	//kPa*L/(K*mol)

code/game/objects/items/tanks/tanks.dm

@@ -241,9 +241,9 @@
 			message_admins("Explosive tank rupture! Last key to touch the tank was [src.fingerprintslast].")
 			log_game("Explosive tank rupture! Last key to touch the tank was [src.fingerprintslast].")
 		//Give the gas a chance to build up more pressure through reacting
-		air_contents.react()
+		air_contents.react(src)
-		air_contents.react()
+		air_contents.react(src)
-		air_contents.react()
+		air_contents.react(src)
 		pressure = air_contents.return_pressure()
 		var/range = (pressure-TANK_FRAGMENT_PRESSURE)/TANK_FRAGMENT_SCALE
 		var/turf/epicenter = get_turf(loc)

code/modules/atmospherics/environmental/LINDA_fire.dm

@@ -87,7 +87,7 @@
 	else
 		var/datum/gas_mixture/affected = location.air.remove_ratio(volume/location.air.volume)
 		affected.temperature = temperature
-		affected.react()
+		affected.react(src)
 		temperature = affected.temperature
 		volume = affected.reaction_results["fire"]*FIRE_GROWTH_RATE
 		location.assume_air(affected)

code/modules/atmospherics/gasmixtures/gas_mixture.dm

@@ -410,7 +410,7 @@ GLOBAL_LIST_INIT(nonreactive_gases, typecacheof(list(/datum/gas/oxygen, /datum/g
 
 	return ""
 
-/datum/gas_mixture/react(turf/open/dump_location)
+/datum/gas_mixture/react(datum/holder)
 	. = NO_REACTION
 	var/list/cached_gases = gases
 	if(!cached_gases.len)
@@ -459,7 +459,7 @@ GLOBAL_LIST_INIT(nonreactive_gases, typecacheof(list(/datum/gas/oxygen, /datum/g
 			//at this point, all requirements for the reaction are satisfied. we can now react()
 			*/
 
-			. |= reaction.react(src, dump_location)
+			. |= reaction.react(src, holder)
 			if (. & STOP_REACTIONS)
 				break
 	if(.)

code/modules/atmospherics/gasmixtures/gas_types.dm

@@ -3,7 +3,7 @@ GLOBAL_LIST_INIT(hardcoded_gases, list(/datum/gas/oxygen, /datum/gas/nitrogen, /
 /proc/meta_gas_list()
 	. = subtypesof(/datum/gas)
 	for(var/gas_path in .)
-		var/list/gas_info = new(6)
+		var/list/gas_info = new(7)
 		var/datum/gas/gas = gas_path
 
 		gas_info[META_GAS_SPECIFIC_HEAT] = initial(gas.specific_heat)
@@ -11,6 +11,7 @@ GLOBAL_LIST_INIT(hardcoded_gases, list(/datum/gas/oxygen, /datum/gas/nitrogen, /
 		gas_info[META_GAS_MOLES_VISIBLE] = initial(gas.moles_visible)
 		if(initial(gas.moles_visible) != null)
 			gas_info[META_GAS_OVERLAY] = new /obj/effect/overlay/gas(initial(gas.gas_overlay))
+		gas_info[META_GAS_FUSION_POWER] = initial(gas.dangerous)
 		gas_info[META_GAS_DANGER] = initial(gas.dangerous)
 		gas_info[META_GAS_ID] = initial(gas.id)
 		.[gas_path] = gas_info
@@ -40,7 +41,7 @@ GLOBAL_LIST_INIT(hardcoded_gases, list(/datum/gas/oxygen, /datum/gas/nitrogen, /
 	var/gas_overlay = "" //icon_state in icons/effects/tile_effects.dmi
 	var/moles_visible = null
 	var/dangerous = FALSE //currently used by canisters
-
+	var/fusion_power = 0 //How much the gas accelerates a fusion reaction
 /datum/gas/oxygen
 	id = "o2"
 	specific_heat = 20
@@ -55,6 +56,7 @@ GLOBAL_LIST_INIT(hardcoded_gases, list(/datum/gas/oxygen, /datum/gas/nitrogen, /
 	id = "co2"
 	specific_heat = 30
 	name = "Carbon Dioxide"
+	fusion_power = 2
 
 /datum/gas/plasma
 	id = "plasma"
@@ -86,6 +88,7 @@ GLOBAL_LIST_INIT(hardcoded_gases, list(/datum/gas/oxygen, /datum/gas/nitrogen, /
 	gas_overlay = "nitrous_oxide"
 	moles_visible = 1
 	dangerous = TRUE
+	fusion_power = 2
 
 /datum/gas/nitryl
 	id = "no2"
@@ -94,6 +97,7 @@ GLOBAL_LIST_INIT(hardcoded_gases, list(/datum/gas/oxygen, /datum/gas/nitrogen, /
 	gas_overlay = "nitryl"
 	moles_visible = MOLES_GAS_VISIBLE
 	dangerous = TRUE
+	fusion_power = 1.5
 
 /datum/gas/tritium
 	id = "tritium"
@@ -102,23 +106,24 @@ GLOBAL_LIST_INIT(hardcoded_gases, list(/datum/gas/oxygen, /datum/gas/nitrogen, /
 	gas_overlay = "tritium"
 	moles_visible = MOLES_GAS_VISIBLE
 	dangerous = TRUE
-
+	fusion_power = 2
 /datum/gas/bz
 	id = "bz"
 	specific_heat = 20
 	name = "BZ"
 	dangerous = TRUE
-
+	fusion_power = 2
 /datum/gas/stimulum
 	id = "stim"
 	specific_heat = 5
 	name = "Stimulum"
+	fusion_power = 7
 
 /datum/gas/pluoxium
 	id = "pluox"
 	specific_heat = 80
 	name = "Pluoxium"
-
+	fusion_power = 10
 /obj/effect/overlay/gas
 	icon = 'icons/effects/tile_effects.dmi'
 	mouse_opacity = MOUSE_OPACITY_TRANSPARENT

code/modules/atmospherics/gasmixtures/reactions.dm

@@ -66,6 +66,7 @@
 	priority = INFINITY
 	name = "Hyper-Noblium Reaction Supression"
 	id = "nobstop"
+
 /datum/gas_reaction/nobliumsupression/init_reqs()
 	min_requirements = list(/datum/gas/hypernoblium = REACTION_OPPRESSION_THRESHOLD)
 
@@ -81,7 +82,8 @@
 /datum/gas_reaction/water_vapor/init_reqs()
 	min_requirements = list(/datum/gas/water_vapor = MOLES_GAS_VISIBLE)
 
-/datum/gas_reaction/water_vapor/react(datum/gas_mixture/air, turf/open/location)
+/datum/gas_reaction/water_vapor/react(datum/gas_mixture/air, datum/holder)
+	var/turf/open/location = isturf(holder) ? holder : null
 	. = NO_REACTION
 	if (air.temperature <= WATER_VAPOR_FREEZE)
 		if(location && location.freon_gas_act())
@@ -99,13 +101,14 @@
 /datum/gas_reaction/fire/init_reqs()
 	min_requirements = list("TEMP" = FIRE_MINIMUM_TEMPERATURE_TO_EXIST) //doesn't include plasma reqs b/c of other, rarer, burning gases.
 
-/datum/gas_reaction/fire/react(datum/gas_mixture/air, turf/open/location)
+/datum/gas_reaction/fire/react(datum/gas_mixture/air, datum/holder)
 	var/energy_released = 0
 	var/old_heat_capacity = air.heat_capacity()
 	var/list/cached_gases = air.gases //this speeds things up because accessing datum vars is slow
 	var/temperature = air.temperature
 	var/list/cached_results = air.reaction_results
 	cached_results[id] = 0
+	var/turf/open/location = isturf(holder) ? holder : null
 
 	//General volatile gas burn
 	if(cached_gases[/datum/gas/tritium] && cached_gases[/datum/gas/tritium][MOLES])
@@ -184,55 +187,76 @@
 
 	return cached_results[id] ? REACTING : NO_REACTION
 
-//fusion: a terrible idea that was fun but broken. Now reworked to be less broken and more interesting.
+//fusion: a terrible idea that was fun but broken. Now reworked to be less broken and more interesting. Again.
 /datum/gas_reaction/fusion
-	exclude = TRUE
+	exclude = FALSE
 	priority = 2
 	name = "Plasmic Fusion"
 	id = "fusion"
 
+
 /datum/gas_reaction/fusion/init_reqs()
 	min_requirements = list(
-		"ENER" = PLASMA_BINDING_ENERGY * 10,
+		"ENER" = PLASMA_BINDING_ENERGY * 1000,
-		/datum/gas/plasma = MINIMUM_HEAT_CAPACITY,
+		/datum/gas/plasma = 50,
-		/datum/gas/tritium = MINIMUM_HEAT_CAPACITY
+		/datum/gas/carbon_dioxide = 1
 	)
 
-/datum/gas_reaction/fusion/react(datum/gas_mixture/air, turf/open/location)
+/datum/gas_reaction/fusion/react(datum/gas_mixture/air, datum/holder)
 	var/list/cached_gases = air.gases
 	var/temperature = air.temperature
-
+	var/turf/open/location
-	if(((cached_gases[/datum/gas/plasma][MOLES]+cached_gases[/datum/gas/tritium][MOLES])/air.total_moles() < FUSION_PURITY_THRESHOLD) || air.return_pressure() < 10*ONE_ATMOSPHERE)
+	if (istype(holder,/datum/pipeline)) //Find the tile the reaction is occuring on, or a random part of the network if it's a pipenet.
-		//Fusion wont occur if the level of impurities is too high or if there is too little pressure.
+		var/datum/pipeline/fusion_pipenet = holder
-		return NO_REACTION
+		location = get_turf(pick(fusion_pipenet.members))
+	else
+		location = get_turf(holder)
 
 	var/old_heat_capacity = air.heat_capacity()
-	var/catalyst_efficency = max(min(cached_gases[/datum/gas/plasma][MOLES]/cached_gases[/datum/gas/tritium][MOLES],MAX_CATALYST_EFFICENCY)-(temperature/FUSION_HEAT_DROPOFF),1)
+	var/reaction_energy
-	var/reaction_energy = THERMAL_ENERGY(air)
+	var/mediation = 100*(air.heat_capacity()-(cached_gases[/datum/gas/plasma][MOLES]*cached_gases[/datum/gas/plasma][GAS_META][META_GAS_SPECIFIC_HEAT]))/(air.total_moles()-cached_gases[/datum/gas/plasma][MOLES]) //This is the average heat capacity of the mixture,not including plasma.
-	var/moles_impurities = max(air.total_moles()-(cached_gases[/datum/gas/plasma][MOLES]+cached_gases[/datum/gas/tritium][MOLES]),1) //This makes it assume a minimum of 1 mol impurities so the reaction energy doesn't divide by 0
+	var/gas_power = 0
+	for (var/id in cached_gases)
+		gas_power += cached_gases[id][GAS_META][META_GAS_FUSION_POWER]*cached_gases[id][MOLES]
+	var/plasma_fused = 0
+	var/power_ratio = min(gas_power/mediation,100)//100 is a lot, we really don't want to go over this.
+	if (power_ratio > 10) //Super-fusion. Fuses everything into one big atom which then turns to tritium instantly. Very dangerous, but super cool.
+		var/gases_fused = air.total_moles()
+		reaction_energy += gases_fused*PLASMA_BINDING_ENERGY*(gas_power/(mediation*100))
+		for (var/id in cached_gases)
+			cached_gases[id][MOLES] = 0
+		air.assert_gas(/datum/gas/tritium)
+		cached_gases[/datum/gas/tritium][MOLES] += gases_fused
+		if (prob(power_ratio)) //You really don't want this to happen
+			empulse(location, power_ratio*0.5, power_ratio)
+			radiation_pulse(location, power_ratio*2000)
+			explosion(location,0,1,power_ratio*0.5,power_ratio,TRUE,TRUE)//Bypasses cap. Doesn't blow large hole in station, but produces moderate devestation for long ranges. Be careful with this.
 
-	var/plasma_fused = min((PLASMA_FUSED_COEFFICENT*catalyst_efficency)*(temperature/PLASMA_BINDING_ENERGY)/10,cached_gases[/datum/gas/plasma][MOLES]) //Preserve matter
+	else if (power_ratio > 1) //Mediation is overpowered, fusion reaction starts to break down.
-	var/tritium_catalyzed = min((CATALYST_COEFFICENT*catalyst_efficency)*(temperature/PLASMA_BINDING_ENERGY)/40,cached_gases[/datum/gas/tritium][MOLES]) //Ditto
+		plasma_fused = cached_gases[/datum/gas/plasma][MOLES]
-	var/oxygen_added = tritium_catalyzed
+		reaction_energy += plasma_fused*PLASMA_BINDING_ENERGY
-	var/waste_added = max((plasma_fused-oxygen_added)-((air.total_moles()*air.heat_capacity())/PLASMA_BINDING_ENERGY),0)
+		cached_gases[/datum/gas/plasma][MOLES] -= plasma_fused
-	reaction_energy = max(reaction_energy+((catalyst_efficency*cached_gases[/datum/gas/plasma][MOLES])/((moles_impurities/catalyst_efficency)+2)*10)+((plasma_fused/(moles_impurities/catalyst_efficency))*PLASMA_BINDING_ENERGY),0)
+		cached_gases[/datum/gas/carbon_dioxide][MOLES] = 0
-
+		air.assert_gases(/datum/gas/bz,/datum/gas/nitrous_oxide)
-	air.assert_gases(/datum/gas/oxygen, /datum/gas/carbon_dioxide, /datum/gas/water_vapor, /datum/gas/nitrous_oxide, /datum/gas/nitryl)
+		cached_gases[/datum/gas/bz][MOLES] += gas_power*0.05
-	//Fusion produces an absurd amount of waste products now, requiring active filtration.
+		cached_gases[/datum/gas/nitrous_oxide][MOLES] += gas_power*0.05
-	cached_gases[/datum/gas/plasma][MOLES] = max(cached_gases[/datum/gas/plasma][MOLES] - plasma_fused,0)
+		if (location)
-	cached_gases[/datum/gas/tritium][MOLES] = max(cached_gases[/datum/gas/tritium][MOLES] - tritium_catalyzed,0)
+			empulse(location, mediation*0.002, mediation*0.004)
-	cached_gases[/datum/gas/oxygen][MOLES] += oxygen_added
+			radiation_pulse(location, power_ratio*(reaction_energy)/(0.3*PLASMA_BINDING_ENERGY))
-	cached_gases[/datum/gas/water_vapor][MOLES] += waste_added
+	else
-	cached_gases[/datum/gas/nitrous_oxide][MOLES] += waste_added
+		reaction_energy += cached_gases[/datum/gas/plasma][MOLES]*PLASMA_BINDING_ENERGY*(gas_power/mediation)
-	cached_gases[/datum/gas/nitryl][MOLES] += waste_added
+		air.assert_gas(/datum/gas/oxygen)
-	cached_gases[/datum/gas/carbon_dioxide][MOLES] += waste_added
+		cached_gases[/datum/gas/oxygen][MOLES] += gas_power + cached_gases[/datum/gas/plasma][MOLES]
-	if (location)
+		cached_gases[/datum/gas/plasma][MOLES] = 0
-		radiation_pulse(location, reaction_energy/(PLASMA_BINDING_ENERGY*MAX_CATALYST_EFFICENCY))
+		for (var/gas in cached_gases)
+			if (cached_gases[gas][GAS_META][META_GAS_FUSION_POWER])
+				cached_gases[gas][MOLES] = 0
+		if (location)
+			radiation_pulse(location, (reaction_energy)/(0.3*PLASMA_BINDING_ENERGY))
 	if(reaction_energy > 0)
 		var/new_heat_capacity = air.heat_capacity()
 		if(new_heat_capacity > MINIMUM_HEAT_CAPACITY)
 			air.temperature = max(((temperature*old_heat_capacity + reaction_energy)/new_heat_capacity),TCMB)
-			//Prevents whatever mechanism is causing it to hit negative temperatures.
 		return REACTING
 
 /datum/gas_reaction/nitrylformation //The formation of nitryl. Endothermic. Requires N2O as a catalyst.
@@ -256,7 +280,8 @@
 	var/heat_efficency = min(temperature/(FIRE_MINIMUM_TEMPERATURE_TO_EXIST*100),cached_gases[/datum/gas/oxygen][MOLES],cached_gases[/datum/gas/nitrogen][MOLES])
 	var/energy_used = heat_efficency*NITRYL_FORMATION_ENERGY
 	ASSERT_GAS(/datum/gas/nitryl,air)
-
+	if ((cached_gases[/datum/gas/oxygen][MOLES] - heat_efficency < 0 )|| (cached_gases[/datum/gas/nitrogen][MOLES] - heat_efficency < 0)) //Shouldn't produce gas from nothing.
+		return NO_REACTION
 	cached_gases[/datum/gas/oxygen][MOLES] -= heat_efficency
 	cached_gases[/datum/gas/nitrogen][MOLES] -= heat_efficency
 	cached_gases[/datum/gas/nitryl][MOLES] += heat_efficency*2
@@ -287,11 +312,12 @@
 	var/old_heat_capacity = air.heat_capacity()
 	var/reaction_efficency = min(1/((pressure/(0.1*ONE_ATMOSPHERE))*(max(cached_gases[/datum/gas/plasma][MOLES]/cached_gases[/datum/gas/tritium][MOLES],1))),cached_gases[/datum/gas/tritium][MOLES],cached_gases[/datum/gas/plasma][MOLES]/2)
 	var/energy_released = 2*reaction_efficency*FIRE_CARBON_ENERGY_RELEASED
-
+	if ((cached_gases[/datum/gas/tritium][MOLES] - reaction_efficency < 0 )|| (cached_gases[/datum/gas/plasma][MOLES] - (2*reaction_efficency) < 0)) //Shouldn't produce gas from nothing.
+		return NO_REACTION
 	ASSERT_GAS(/datum/gas/bz,air)
-	cached_gases[/datum/gas/bz][MOLES]+= reaction_efficency
+	cached_gases[/datum/gas/bz][MOLES] += reaction_efficency
-	cached_gases[/datum/gas/tritium][MOLES] = max(cached_gases[/datum/gas/tritium][MOLES]- reaction_efficency,0)
+	cached_gases[/datum/gas/tritium][MOLES] -= reaction_efficency
-	cached_gases[/datum/gas/plasma][MOLES] = max(cached_gases[/datum/gas/plasma][MOLES] - (2*reaction_efficency),0)
+	cached_gases[/datum/gas/plasma][MOLES]  -= 2*reaction_efficency
 
 
 	if(energy_released > 0)
@@ -320,10 +346,12 @@
 	var/stim_energy_change = heat_scale + STIMULUM_FIRST_RISE*(heat_scale**2) - STIMULUM_FIRST_DROP*(heat_scale**3) + STIMULUM_SECOND_RISE*(heat_scale**4) - STIMULUM_ABSOLUTE_DROP*(heat_scale**5)
 
 	ASSERT_GAS(/datum/gas/stimulum,air)
+	if ((cached_gases[/datum/gas/tritium][MOLES] - heat_scale < 0 )|| (cached_gases[/datum/gas/plasma][MOLES] - heat_scale < 0) || (cached_gases[/datum/gas/nitryl][MOLES] - heat_scale < 0)) //Shouldn't produce gas from nothing.
+		return NO_REACTION
 	cached_gases[/datum/gas/stimulum][MOLES]+= heat_scale/10
-	cached_gases[/datum/gas/tritium][MOLES] = max(cached_gases[/datum/gas/tritium][MOLES]- heat_scale,0)
+	cached_gases[/datum/gas/tritium][MOLES] -= heat_scale
-	cached_gases[/datum/gas/plasma][MOLES] = max(cached_gases[/datum/gas/plasma][MOLES]- heat_scale,0)
+	cached_gases[/datum/gas/plasma][MOLES] -= heat_scale
-	cached_gases[/datum/gas/nitryl][MOLES] = max(cached_gases[/datum/gas/nitryl][MOLES]- heat_scale,0)
+	cached_gases[/datum/gas/nitryl][MOLES] -= heat_scale
 
 	if(stim_energy_change)
 		var/new_heat_capacity = air.heat_capacity()
@@ -348,6 +376,8 @@
 	var/old_heat_capacity = air.heat_capacity()
 	var/nob_formed = min((cached_gases[/datum/gas/nitrogen][MOLES]+cached_gases[/datum/gas/tritium][MOLES])/100,cached_gases[/datum/gas/tritium][MOLES]/10,cached_gases[/datum/gas/nitrogen][MOLES]/20)
 	var/energy_taken = nob_formed*(NOBLIUM_FORMATION_ENERGY/(max(cached_gases[/datum/gas/bz][MOLES],1)))
+	if ((cached_gases[/datum/gas/tritium][MOLES] - 10*nob_formed < 0) || (cached_gases[/datum/gas/nitrogen][MOLES] - 20*nob_formed < 0))
+		return NO_REACTION
 	cached_gases[/datum/gas/tritium][MOLES] = max(cached_gases[/datum/gas/tritium][MOLES]- 10*nob_formed,0)
 	cached_gases[/datum/gas/nitrogen][MOLES] = max(cached_gases[/datum/gas/nitrogen][MOLES]- 20*nob_formed,0)
 	cached_gases[/datum/gas/hypernoblium][MOLES]+= nob_formed

code/modules/atmospherics/machinery/datum_pipeline.dm

@@ -27,7 +27,7 @@
 	if(update)
 		update = FALSE
 		reconcile_air()
-	update = air.react()
+	update = air.react(src)
 
 /datum/pipeline/proc/build_pipeline(obj/machinery/atmospherics/base)
 	var/volume = 0

code/modules/atmospherics/machinery/portable/portable_atmospherics.dm

@@ -35,7 +35,7 @@
 
 /obj/machinery/portable_atmospherics/process_atmos()
 	if(!connected_port) // Pipe network handles reactions if connected.
-		air_contents.react()
+		air_contents.react(src)
 	else
 		update_icon()
 

code/modules/projectiles/guns/misc/blastcannon.dm

@@ -65,7 +65,7 @@
 	temp.merge(bomb.tank_one.air_contents.remove_ratio(1))
 	temp.merge(bomb.tank_two.air_contents.remove_ratio(2))
 	for(var/i in 1 to 6)
-		temp.react()
+		temp.react(src)
 	var/pressure = temp.return_pressure()
 	qdel(temp)
 	if(pressure < TANK_FRAGMENT_PRESSURE)

code/modules/reagents/chemistry/reagents/food_reagents.dm

@@ -438,7 +438,7 @@
 	if(hotspot)
 		var/datum/gas_mixture/lowertemp = T.remove_air(T.air.total_moles())
 		lowertemp.temperature = max( min(lowertemp.temperature-2000,lowertemp.temperature / 2) ,0)
-		lowertemp.react()
+		lowertemp.react(src)
 		T.assume_air(lowertemp)
 		qdel(hotspot)
 

code/modules/reagents/chemistry/reagents/other_reagents.dm

@@ -146,7 +146,7 @@
 		if(T.air)
 			var/datum/gas_mixture/G = T.air
 			G.temperature = max(min(G.temperature-(CT*1000),G.temperature/CT),0)
-			G.react()
+			G.react(src)
 			qdel(hotspot)
 	var/obj/effect/acid/A = (locate(/obj/effect/acid) in T)
 	if(A)

code/modules/reagents/chemistry/reagents/pyrotechnic_reagents.dm

@@ -273,7 +273,7 @@
 			var/datum/gas_mixture/G = T.air
 			if(G.temperature > T20C)
 				G.temperature = max(G.temperature/2,T20C)
-			G.react()
+			G.react(src)
 			qdel(hotspot)
 
 /datum/reagent/firefighting_foam/reaction_obj(obj/O, reac_volume)