A preliminary implementation of chem gases

code/modules/reagents/chemistry/reagents.dm

@@ -54,6 +54,9 @@ GLOBAL_LIST_INIT(name2reagent, build_name2reagent())
 	var/chemical_flags // See fermi/readme.dm REAGENT_DEAD_PROCESS, REAGENT_DONOTSPLIT, REAGENT_ONLYINVERSE, REAGENT_ONMOBMERGE, REAGENT_INVISIBLE, REAGENT_FORCEONNEW, REAGENT_SNEAKYNAME
 	var/value = REAGENT_VALUE_NONE //How much does it sell for in cargo?
 	var/datum/material/material //are we made of material?
+	var/gas //do we have an associated gas?
+	var/boiling_point = null // point at which this gas boils; if null, will never boil (and thus not become a gas)
+	var/condensation_amount = 1
 
 /datum/reagent/New()
 	. = ..()
@@ -80,8 +83,18 @@ GLOBAL_LIST_INIT(name2reagent, build_name2reagent())
 /datum/reagent/proc/reaction_obj(obj/O, volume)
 	return
 
-/datum/reagent/proc/reaction_turf(turf/T, volume)
-	return
+/datum/reagent/proc/reaction_turf(turf/T, volume, show_message, from_gas)
+	if(!from_gas && boiling_point)
+		var/temp = holder?.chem_temp
+		if(!temp)
+			if(isopenturf(T))
+				var/turf/open/O = T
+				var/datum/gas_mixture/air = O.return_air()
+				temp = air.return_temperature()
+			else
+				temp = T20C
+		if(temp > boiling_point)
+			T.atmos_spawn_air("[get_gas()]=[volume/2];TEMP=[temp]")
 
 /datum/reagent/proc/on_mob_life(mob/living/carbon/M)
 	current_cycle++
@@ -231,6 +244,46 @@ GLOBAL_LIST_INIT(name2reagent, build_name2reagent())
 
 	return rs.Join(" | ")
 
+/datum/reagent/proc/define_gas()
+	if(reagent_state == SOLID)
+		return null // doesn't make that much sense
+	var/list/cached_reactions = GLOB.chemical_reactions_list
+	for(var/reaction in cached_reactions[src.type])
+		var/datum/chemical_reaction/C = reaction
+		if(!istype(C))
+			continue
+		if(C.required_reagents.len < 2) // no reagents that react on their own
+			return null
+	var/datum/gas/G = new
+	G.id = "[src.type]"
+	G.name = name
+	G.specific_heat = specific_heat / 10
+	G.color = color
+	G.breath_reagent = src.type
+	G.turf_reagent = src.type
+	return G
+
+/datum/reagent/proc/create_gas()
+	var/datum/gas/G = define_gas()
+	if(istype(G)) // if this reagent should never be a gas, define_gas may return null
+		GLOB.gas_data.add_gas(G)
+
+/datum/reagent/proc/get_gas()
+	if(gas)
+		return gas
+	else
+		var/datum/auxgm/cached_gas_data = GLOB.gas_data
+		. = "[src.type]"
+		if(!(. in cached_gas_data.ids))
+			var/datum/gas/G = define_gas()
+			if(istype(G))
+				cached_gas_data.add_gas(G)
+			else // this codepath should probably not happen at all, since we never use get_gas() on anything with no boiling point
+				return null
+
+
+
+
 //For easy bloodsucker disgusting and blood removal
 /datum/reagent/proc/disgust_bloodsucker(mob/living/carbon/C, disgust, blood_change, blood_puke = TRUE, force)
 	if(AmBloodsucker(C))