Merge pull request #6171 from mwerezak/gas-entropy

Fixes gas entropy calculation + engine pump/injector flow imbalance issue

code/ATMOSPHERICS/components/unary/vent_pump.dm

@@ -169,7 +169,7 @@
 			var/transfer_moles = pressure_delta*output_volume/(air_temperature * R_IDEAL_GAS_EQUATION)
 			
 			//limit flow rate from turfs
-			transfer_moles = min(transfer_moles, environment.total_moles*MAX_SIPHON_FLOWRATE/environment.volume)	//group_multiplier gets divided out here
+			transfer_moles = min(transfer_moles, environment.total_moles*air_contents.volume/environment.volume)	//group_multiplier gets divided out here
 			
 			power_draw = pump_gas(src, environment, air_contents, transfer_moles, active_power_usage)
 

code/ZAS/_gas_mixture_xgm.dm

@@ -128,15 +128,27 @@
 		. += ratio * specific_entropy_gas(g)
 	. /= total_moles
 
-//Returns the ideal gas specific entropy of a specific gas in the mix. This is the entropy due to that gas per mole of /that/ gas in the mixture, not the entropy due to that gas per mole of gas mixture.
+/*
+	Returns the ideal gas specific entropy of a specific gas in the mix. This is the entropy due to that gas per mole of /that/ gas in the mixture, not the entropy due to that gas per mole of gas mixture.
+	
+	For the purposes of SS13, the specific entropy is just a number that tells you how hard it is to move gas. You can replace this with whatever you want.
+	Just remember that returning a SMALL number == adding gas to this gas mix is HARD, taking gas away is EASY, and that returning a LARGE number means the opposite (so a vacuum would approach infinity).
+
+	So returning a constant/(partial pressure) would probably do what most players expect. Although the version I have implemented below is a bit more nuanced than simply 1/P in that it scales in a way 
+	which is bit more realistic (natural log), and returns a fairly accurate entropy around room temperatures and pressures.
+*/
 /datum/gas_mixture/proc/specific_entropy_gas(var/gasid)
 	if (!(gasid in gas) || gas[gasid] == 0)
 		return SPECIFIC_ENTROPY_VACUUM	//that gas isn't here
 	
 	var/molar_mass = gas_data.molar_mass[gasid]
 	var/specific_heat = gas_data.specific_heat[gasid]
-	//group_multiplier gets divided out in volume/gas[gasid]
-	return R_IDEAL_GAS_EQUATION * ( log( (IDEAL_GAS_ENTROPY_CONSTANT*volume/gas[gasid]) * sqrt((molar_mass*specific_heat*temperature)**3) + 1 ) +  5/2 )
+	
+	//group_multiplier gets divided out in volume/gas[gasid] - also, V/(m*T) = R/(partial pressure)
+	//This equation is not accurate at all, but should work well enough for a game. 
+	//Based on the form of Sackur-Tetrode + some curve fitting to specific entropy tables for N2 gas + some adjustments to make it work down to 0 K 
+	//(the real S-T equation does not work at low temperatures, you need quantum mechanics to do it, but screw that) and with the specific power atmos machinery calculations.
+	return R_IDEAL_GAS_EQUATION * ( log( (IDEAL_GAS_ENTROPY_CONSTANT*volume/(gas[gasid] * temperature)) * (molar_mass*specific_heat*temperature)**(2/3) + 1 ) +  15 )
 
 //Updates the total_moles count and trims any empty gases.
 /datum/gas_mixture/proc/update_values()

code/modules/power/singularity/collector.dm

@@ -13,6 +13,7 @@ var/global/list/rad_collectors = list()
 //	use_power = 0
 	var/obj/item/weapon/tank/phoron/P = null
 	var/last_power = 0
+	var/last_power_new = 0
 	var/active = 0
 	var/locked = 0
 	var/drainratio = 1
@@ -26,6 +27,11 @@ var/global/list/rad_collectors = list()
 	..()
 
 /obj/machinery/power/rad_collector/process()
+	//so that we don't zero out the meter if the SM is processed first.
+	last_power = last_power_new
+	last_power_new = 0
+	
+
 	if(P)
 		if(P.air_contents.gas["phoron"] == 0)
 			investigate_log("<font color='red'>out of fuel</font>.","singulo")
@@ -50,10 +56,7 @@ var/global/list/rad_collectors = list()
 
 
 /obj/machinery/power/rad_collector/attackby(obj/item/W, mob/user)
-	if(istype(W, /obj/item/device/analyzer))
-		user << "\blue The [W.name] detects that [last_power]W were recently produced."
-		return 1
-	else if(istype(W, /obj/item/weapon/tank/phoron))
+	if(istype(W, /obj/item/weapon/tank/phoron))
 		if(!src.anchored)
 			user << "\red The [src] needs to be secured to the floor first."
 			return 1
@@ -96,6 +99,11 @@ var/global/list/rad_collectors = list()
 		..()
 		return 1
 
+/obj/machinery/power/rad_collector/examine()
+	..()
+	if (get_dist(usr, src) <= 3)
+		usr << "The meter indicates that \the [src] is collecting [last_power] W."
+		return 1
 
 /obj/machinery/power/rad_collector/ex_act(severity)
 	switch(severity)
@@ -122,7 +130,7 @@ var/global/list/rad_collectors = list()
 		var/power_produced = 0
 		power_produced = P.air_contents.gas["phoron"]*pulse_strength*20
 		add_avail(power_produced)
-		last_power = power_produced
+		last_power_new = power_produced
 		return
 	return
 

code/modules/power/singularity/emitter.dm

@@ -1,4 +1,4 @@
-#define EMITTER_DAMAGE_POWER_TRANSFER 400 //used to transfer power to containment field generators
+#define EMITTER_DAMAGE_POWER_TRANSFER 450 //used to transfer power to containment field generators
 
 /obj/machinery/power/emitter
 	name = "Emitter"

code/setup.dm

@@ -837,8 +837,8 @@ var/list/RESTRICTED_CAMERA_NETWORKS = list( //Those networks can only be accesse
 
 //These balance how easy or hard it is to create huge pressure gradients with pumps and filters. Lower values means it takes longer to create large pressures differences.
 //Has no effect on pumping gasses from high pressure to low, only from low to high. Must be between 0 and 1.
-#define ATMOS_PUMP_EFFICIENCY	0.6
-#define ATMOS_FILTER_EFFICIENCY	0.45
+#define ATMOS_PUMP_EFFICIENCY	1.0
+#define ATMOS_FILTER_EFFICIENCY	1.0
 
 //will not bother pumping or filtering if the gas source as fewer than this amount of moles, to help with performance.
 #define MINUMUM_MOLES_TO_PUMP	0.01