Adds gas filtering proc

code/ATMOSPHERICS/atmospherics_helpers.dm

@@ -2,22 +2,26 @@
 	Atmos processes
 	
 	These procs generalize various processes used by atmos machinery, such as pumping, filtering, or scrubbing gas, allowing them to be reused elsewhere.
+	If no gas was moved/pumped/filtered/whatever, they return a negative number.
+	Otherwise they return the amount of energy needed to do whatever it is they do (equivalently power if done over 1 second).
+	In the case of free-flowing gas you can do things with gas and still use 0 power, hence the distinction between negative and non-negative return values.
 */
 
 
+/obj/machinery/atmospherics/var/last_flow_rate = 0	//Can't return multiple values, unfortunately
+
 //Generalized gas pumping proc.
 //Moves gas from one gas_mixture to another and returns the amount of power needed (assuming 1 second), or -1 if no gas was pumped.
 //transfer_moles - Limits the amount of moles to transfer. The actual amount of gas moved may also be limited by available_power, if given.
 //available_power - the maximum amount of power that may be used when moving gas. If null then the transfer is not limited by power.
-
-/obj/machinery/atmospherics/var/last_flow_rate = 0	//Can't return multiple values, unfortunately...
-
 /obj/machinery/atmospherics/proc/pump_gas(var/datum/gas_mixture/source, var/datum/gas_mixture/sink, var/transfer_moles = null, var/available_power = null)
-	if (source.total_moles < MINUMUM_MOLES_TO_PUMP)
+	if (source.total_moles < MINUMUM_MOLES_TO_PUMP) //if we cant transfer enough gas just stop to avoid further processing
 		return -1
 	
 	if (!transfer_moles)
 		transfer_moles = source.total_moles
+	else
+		transfer_moles = min(source.total_moles, transfer_moles)
 	
 	//Calculate the amount of energy required and limit transfer_moles based on available power
 	var/specific_power = calculate_specific_power(source, sink)/ATMOS_PUMP_EFFICIENCY //this has to be calculated before we modify any gas mixtures
@@ -30,7 +34,7 @@
 	last_flow_rate = (transfer_moles/source.total_moles)*source.volume //group_multiplier gets divided out here
 	
 	var/datum/gas_mixture/removed = source.remove(transfer_moles)
-	if (isnull(removed)) //not sure why this would happen, but it does at the very beginning of the game
+	if (!removed) //Just in case
 		return -1
 	
 	var/power_draw = specific_power*transfer_moles
@@ -47,7 +51,7 @@
 //total_transfer_moles - Limits the amount of moles to scrub. The actual amount of gas scrubbed may also be limited by available_power, if given.
 //available_power - the maximum amount of power that may be used when scrubbing gas. If null then the scrubbing is not limited by power.
 /obj/machinery/atmospherics/proc/scrub_gas(var/list/filtering, var/datum/gas_mixture/source, var/datum/gas_mixture/sink, var/total_transfer_moles = null, var/available_power = null)
-	if (source.total_moles < MINUMUM_MOLES_TO_FILTER)
+	if (source.total_moles < MINUMUM_MOLES_TO_FILTER) //if we cant transfer enough gas just stop to avoid further processing
 		return -1
 
 	filtering &= source.gas		//only filter gasses that are actually there.
@@ -63,12 +67,12 @@
 		specific_power_gas[g] = specific_power
 		total_filterable_moles += source.gas[g]
 	
-	if (total_filterable_moles < MINUMUM_MOLES_TO_FILTER)
+	if (total_filterable_moles < MINUMUM_MOLES_TO_FILTER) //if we cant transfer enough gas just stop to avoid further processing
 		return -1
 	
 	var/total_specific_power = 0		//the power required to remove one mole of filterable gas
 	for (var/g in filtering)
-		var/ratio = source.gas[g]/total_filterable_moles //converts the specific power per mole of pure gas to specific power per mole of filterable gas mix
+		var/ratio = source.gas[g]/total_filterable_moles //this converts the specific power per mole of pure gas to specific power per mole of filterable gas mix
 		total_specific_power = specific_power_gas[g]*ratio
 	
 	//Figure out how much of each gas to filter
@@ -81,7 +85,7 @@
 	if (available_power && total_specific_power > 0)
 		total_transfer_moles = min(total_transfer_moles, available_power/total_specific_power)
 	
-	if (total_transfer_moles < MINUMUM_MOLES_TO_FILTER) //we check this repeatedly so that we do as little processing as possible
+	if (total_transfer_moles < MINUMUM_MOLES_TO_FILTER) //if we cant transfer enough gas just stop to avoid further processing
 		return -1
 	
 	var/power_draw = 0
@@ -91,19 +95,101 @@
 		//filter gas in proportion to the mole ratio
 		transfer_moles = min(transfer_moles, total_transfer_moles*(source.gas[g]/total_filterable_moles))
 		
-		source.gas[g] -= transfer_moles
-		sink.gas[g] += transfer_moles		//do we need to check if g is in sink.gas first?
+		//use update=0. All the filtered gasses get added simultaneously, so we update after the for loop.
+		source.adjust_gas(g, -transfer_moles, update=0)
+		sink.adjust_gas_temp(g, transfer_moles, source.temperature, update=0)
+		
 		power_draw += specific_power_gas[g]*transfer_moles
 	
-	if (power_draw > 0)
-		sink.add_thermal_energy(power_draw)	//gotta conserve that energy
-	
 	//Remix the resulting gases
 	sink.update_values()
 	source.update_values()
 	
+	if (power_draw > 0)
+		sink.add_thermal_energy(power_draw)	//gotta conserve that energy
+	
 	return power_draw
 
+//Generalized gas filtering proc.
+//Filtering is a bit different from scrubbing. Instead of selectively moving the targeted gas types from one gas mix to another, filtering splits 
+//the input gas into two outputs: one that contains /only/ the targeted gas types, and another that completely clean of the targeted gas types.
+//filtering - A list of gasids to be filtered. These gasses get moved to sink_filtered, while the other gasses get moved to sink_clean.
+//total_transfer_moles - Limits the amount of moles to input. The actual amount of gas filtered may also be limited by available_power, if given.
+//available_power - the maximum amount of power that may be used when filtering gas. If null then the filtering is not limited by power.
+/obj/machinery/atmospherics/proc/filter_gas(var/list/filtering, var/datum/gas_mixture/source, var/datum/gas_mixture/sink_filtered, var/datum/gas_mixture/sink_clean, var/total_transfer_moles = null, var/available_power = null)
+	if (source.total_moles < MINUMUM_MOLES_TO_FILTER) //if we cant transfer enough gas just stop to avoid further processing
+		return -1
+
+	filtering &= source.gas		//only filter gasses that are actually there.
+	var/list/not_filtering = source.gas - filtering
+	
+	var/total_filterable_moles = 0
+	var/total_unfilterable_moles = 0
+	var/list/specific_power_gas = list()	//the power required to remove one mole of pure gas, for each gas type
+	for (var/g in source.gas)
+		if (source.gas[g] < MINUMUM_MOLES_TO_FILTER)
+			continue
+		
+		if (g in filtering)
+			specific_power_gas[g] = calculate_specific_power_gas(g, source, sink_filtered)/ATMOS_FILTER_EFFICIENCY
+			total_filterable_moles += source.gas[g]
+		else
+			specific_power_gas[g] = calculate_specific_power_gas(g, source, sink_clean)/ATMOS_FILTER_EFFICIENCY
+			total_unfilterable_moles += source.gas[g]
+	
+	var/total_specific_power = 0		//the power required to remove one mole of input gas
+	for (var/g in source.gas)
+		var/ratio = source.gas[g]/source.total_moles //converts the specific power per mole of pure gas to specific power per mole of input gas mix
+		total_specific_power = specific_power_gas[g]*ratio
+	
+	//Figure out how much of each gas to filter
+	if (!total_transfer_moles)
+		total_transfer_moles = source.total_moles
+	else
+		total_transfer_moles = min(total_transfer_moles, source.total_moles)
+	
+	//limit transfer_moles based on available power
+	if (available_power && total_specific_power > 0)
+		total_transfer_moles = min(total_transfer_moles, available_power/total_specific_power)
+	
+	if (total_transfer_moles < MINUMUM_MOLES_TO_FILTER) //if we cant transfer enough gas just stop to avoid further processing
+		return -1
+	
+	last_flow_rate = (total_transfer_moles/source.total_moles)*source.volume //group_multiplier gets divided out here
+	
+	var/datum/gas_mixture/removed = source.remove(total_transfer_moles)
+	if (!removed) //Just in case
+		return -1
+	
+	var/filtered_power_used = 0
+	var/unfiltered_power_used = 0
+	for (var/g in removed.gas)
+		var/power_used = specific_power_gas[g]*removed.gas[g]
+		
+		//use update=0. All the filtered gasses get added simultaneously, so we update after the for loop.
+		if (g in filtering)
+			sink_filtered.adjust_gas_temp(g, removed.gas[g], removed.temperature, update=0)
+			filtered_power_used += power_used
+		else
+			sink_clean.adjust_gas_temp(g, removed.gas[g], removed.temperature, update=0)
+			unfiltered_power_used += power_used
+	
+	sink_filtered.update_values()
+	sink_clean.update_values()
+	
+	del(removed) //removed should have nothing in it now, so we can just get rid of it.
+	
+	if (filtered_power_used > 0)
+		sink_filtered.add_thermal_energy(filtered_power_used) //1st law - energy is conserved
+	if (unfiltered_power_used > 0)
+		sink_clean.add_thermal_energy(unfiltered_power_used) //1st law - energy is conserved
+	
+	return filtered_power_used + unfiltered_power_used
+
+/*
+	Helper procs for various things.
+*/
+
 //Calculates the amount of power needed to move one mole from source to sink.
 /obj/machinery/atmospherics/proc/calculate_specific_power(datum/gas_mixture/source, datum/gas_mixture/sink)
 	//Calculate the amount of energy required