From 1eec1b11ddd449cf7e0f77f049d834102cbbd38b Mon Sep 17 00:00:00 2001
From: r4d6 <50276533+r4d6@users.noreply.github.com>
Date: Sat, 18 Jan 2020 20:00:07 -0500
Subject: [PATCH 1/2] Update passive_vent.dm

---
 .../components/unary_devices/passive_vent.dm  | 52 +++++++++++++------
 1 file changed, 35 insertions(+), 17 deletions(-)

diff --git a/code/modules/atmospherics/machinery/components/unary_devices/passive_vent.dm b/code/modules/atmospherics/machinery/components/unary_devices/passive_vent.dm
index 94d8959987..e01632c379 100644
--- a/code/modules/atmospherics/machinery/components/unary_devices/passive_vent.dm
+++ b/code/modules/atmospherics/machinery/components/unary_devices/passive_vent.dm
@@ -20,28 +20,46 @@
 /obj/machinery/atmospherics/components/unary/passive_vent/process_atmos()
 	..()
 
-	var/datum/gas_mixture/environment = loc.return_air()
-	var/environment_pressure = environment.return_pressure()
-	var/pressure_delta = abs(environment_pressure - airs[1].return_pressure())
+	var/active = FALSE
 
-	if((environment.temperature || airs[1].temperature) && pressure_delta > 0.5)
-		if(environment_pressure < airs[1].return_pressure())
-			var/air_temperature = (environment.temperature > 0) ? environment.temperature : airs[1].temperature
-			var/transfer_moles = (pressure_delta * environment.volume) / (air_temperature * R_IDEAL_GAS_EQUATION)
-			var/datum/gas_mixture/removed = airs[1].remove(transfer_moles)
-			loc.assume_air(removed)
-			air_update_turf()
+	var/datum/gas_mixture/external = loc.return_air()
+	var/datum/gas_mixture/internal = airs[1]
+	var/external_pressure = external.return_pressure()
+	var/internal_pressure = internal.return_pressure()
+	var/pressure_delta = abs(external_pressure - internal_pressure)
+
+	if(pressure_delta > 0.5)
+		if(external_pressure < internal_pressure)
+			var/air_temperature = (external.temperature > 0) ? external.temperature : internal.temperature
+			var/transfer_moles = (pressure_delta * external.volume) / (air_temperature * R_IDEAL_GAS_EQUATION)
+			var/datum/gas_mixture/removed = internal.remove(transfer_moles)
+			external.merge(removed)
 		else
-			var/air_temperature = (airs[1].temperature > 0) ? airs[1].temperature : environment.temperature
-			var/output_volume = airs[1].volume
-			var/transfer_moles = (pressure_delta * output_volume) / (air_temperature * R_IDEAL_GAS_EQUATION)
-			transfer_moles = min(transfer_moles, environment.total_moles()*airs[1].volume/environment.volume)
-			var/datum/gas_mixture/removed = loc.remove_air(transfer_moles)
+			var/air_temperature = (internal.temperature > 0) ? internal.temperature : external.temperature
+			var/transfer_moles = (pressure_delta * internal.volume) / (air_temperature * R_IDEAL_GAS_EQUATION)
+			transfer_moles = min(transfer_moles, external.total_moles() * internal.volume / external.volume)
+			var/datum/gas_mixture/removed = external.remove(transfer_moles)
 			if(isnull(removed))
 				return
 			airs[1].merge(removed)
-			air_update_turf()
-	update_parents()
+			internal.merge(removed)
+
+		active = TRUE
+
+	if(abs(external.temperature - internal.temperature) > MINIMUM_TEMPERATURE_DELTA_TO_CONSIDER)
+		var/external_heat_capacity = external.heat_capacity()
+		var/internal_heat_capacity = internal.heat_capacity()
+		var/combined_heat_capacity = external_heat_capacity + internal_heat_capacity
+		if(combined_heat_capacity)
+			var/temperature = (internal.temperature * internal_heat_capacity + external.temperature * external_heat_capacity) / combined_heat_capacity
+			external.temperature = temperature
+			internal.temperature = temperature
+
+			active = TRUE
+
+	if(active)
+		air_update_turf()
+		update_parents()
 
 /obj/machinery/atmospherics/components/unary/passive_vent/can_crawl_through()
 	return TRUE

From c78944c5bc0fbd4b1f95f8b591d1e61d14e1c076 Mon Sep 17 00:00:00 2001
From: r4d6 <david.moussette@gmail.com>
Date: Wed, 22 Jan 2020 13:47:57 -0500
Subject: [PATCH 2/2] Update

---
 .../components/unary_devices/passive_vent.dm         | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/code/modules/atmospherics/machinery/components/unary_devices/passive_vent.dm b/code/modules/atmospherics/machinery/components/unary_devices/passive_vent.dm
index e01632c379..d1daa720ca 100644
--- a/code/modules/atmospherics/machinery/components/unary_devices/passive_vent.dm
+++ b/code/modules/atmospherics/machinery/components/unary_devices/passive_vent.dm
@@ -41,21 +41,11 @@
 			var/datum/gas_mixture/removed = external.remove(transfer_moles)
 			if(isnull(removed))
 				return
-			airs[1].merge(removed)
 			internal.merge(removed)
 
 		active = TRUE
 
-	if(abs(external.temperature - internal.temperature) > MINIMUM_TEMPERATURE_DELTA_TO_CONSIDER)
-		var/external_heat_capacity = external.heat_capacity()
-		var/internal_heat_capacity = internal.heat_capacity()
-		var/combined_heat_capacity = external_heat_capacity + internal_heat_capacity
-		if(combined_heat_capacity)
-			var/temperature = (internal.temperature * internal_heat_capacity + external.temperature * external_heat_capacity) / combined_heat_capacity
-			external.temperature = temperature
-			internal.temperature = temperature
-
-			active = TRUE
+	active = internal.temperature_share(external, OPEN_HEAT_TRANSFER_COEFFICIENT) ? TRUE : active
 
 	if(active)
 		air_update_turf()