fix?

code/___compile_options.dm

@@ -166,8 +166,9 @@
 // ## Atmospherics
 
 //? Gasmixtures
+
 /// Enable general assertions.
-#define GASMIXTURE_ASSERTIONS
+#define CF_ATMOS_DEBUG_ASSERTIONS
 
 
 //? ZAS (Environmental)

code/modules/atmospherics/environmental/turf-share.dm

@@ -15,14 +15,16 @@
  * * limit_ratio is provided so you can limit the amount of energy transferred to a single segment
  *   of say, a heat exchanging pipeline, as while the entire pipeline has a lot of heat capacity,
  *   an individual pipe segment does not.
-	// * someone please help do the algebra and see equalize_ratio and limit_ratio aren't just able to be collapsed into one term
+ * * someone please help do the algebra and see equalize_ratio and limit_ratio aren't just able to be collapsed into one term
  *
  * @params
  * * temperature - the temperature of the sharer
  * * heat_capacity - the specific heat of the sharer in J / K
  * * limit_ratio - a multiplier for the part of 'heat_capacity' that can be drawn from / added to this tick.
+ *                 The allowable values are: [0, 1].
  * * equalize_ratio - a limit to delta-energy; 0.5 means only transfer up to 50% of the energy needed to equalize.
  *                 Be very, very careful when setting high values of this!
+ *                 The allowable values are: [0, 1].
  * * cell_limit - the maximum effective volume in cells of the share. If we're in a zone with
  *                10 tiles and share_volume is only 2, we will at most equalize the energy
  *                in 1/5 of our zone. This is to artificially limit the effectiveness
@@ -31,26 +33,31 @@
  * @return the temperature change to the sharer
  */
 /turf/proc/air_thermal_superconduction(temperature, heat_capacity, limit_ratio, equalize_ratio, cell_limit)
-	#warn fix
+	#ifdef CF_ATMOS_DEBUG_ASSERTIONS
+	ASSERT(limit_ratio >= 0 && limit_ratio <= 1)
+	ASSERT(equalize_ratio >= 0 && equalize_ratio <= 1)
+	#endif
+	#warn test
 	// unsimulated mixtures
 	var/datum/gas_mixture/sharing_with_immutable = return_air_immutable()
 	// to avoid precision issues, we only want our singular heat capacity
-	var/our_heat_capacity = sharing_with_immutable.heat_capacity_singular()
+	var/our_singular_heat_capacity = sharing_with_immutable.heat_capacity_singular()
 	// then, we divide their capacity by cell limit instead of expand our relative capacity.
-	var/midpoint_t = ((our_heat_capacity * sharing_with_immutable.temperature) + ((heat_capacity / cell_limit) * temperature)) \
-		/ (our_heat_capacity + (heat_capacity / cell_limit))
-	// if this was an actual simulated turf, we'd need to calculate the change
-	// with equalize ratio, and then limit it with limit ratio
-	//
-	// since this is unsimulated, limit ratio is effectively just a secondary
-	// equalize ratio, as the total temperature change is tempered by the
-	// limit ratio limiting the availability of thermal energy to effect that change
-	// (we don't change but the opposite & equal change to the sharer still happens)
+	var/their_effective_capacity = (heat_capacity / cell_limit) * limit_ratio
+	// calculate midpoint temperature
+	var/midpoint_t = ((our_singular_heat_capacity * sharing_with_immutable.temperature) + (their_effective_capacity * temperature)) \
+		/ (our_heat_capacity + their_effective_capacity)
+	// since it's an unsimulated turf, we just care to change their temperature.
 	return (midpoint_t - temperature) * equalize_ratio * limit_ratio
 
 /turf/simulated/air_thermal_superconduction(temperature, heat_capacity, limit_ratio, equalize_ratio, cell_limit)
-	#warn fix
+	#ifdef CF_ATMOS_DEBUG_ASSERTIONS
+	ASSERT(limit_ratio >= 0 && limit_ratio <= 1)
+	ASSERT(equalize_ratio >= 0 && equalize_ratio <= 1)
+	#endif
+	#warn test
 	// simulated mixtures
+	//
 	// the trick is the rest of this proc works regardless of if we're in a zone or not,
 	// because we're using group multiplier manually with cell unit
 	var/datum/gas_mixture/sharing_with_mutable = return_air_mutable()
@@ -63,13 +70,18 @@
 	// also apply limit ratio here to make them even smaller than they are
 	var/their_effective_capacity = (heat_capacity / our_size_multiplier) * limit_ratio
 	// get the temperature 'goal'
+	// this is only taking into account the portion of them (limit_ratio is used)
+	// that we're equalizing with, **not** the whole part!
 	var/midpoint_t = ((our_singular_heat_capacity * sharing_with_mutable.temperature) + (their_effective_capacity * temperature)) / (their_effective_capacity + our_singular_heat_capacity)
-	// equalize ratio is a delta-energy modifier
-	// we don't want equalize ratio to affect the 'true' target temperature,
-	// only how much is actually transferred
-	// we also don't want to not multiply full energy transfer because it'll get precision issues
+	// this is the temperature change to the part of them that limit_ratio allows for.
+	// so this has the heat capacity of `heat_capacity * limit_ratio`.
+	// this does not care about our effective size multiplier,
+	// as that is used to bias the temperature change, as opposed to representing
+	// any change to the total energy being transferred.
 	var/temperature_change_to_them = (midpoint_t - temperature) * equalize_ratio
 	// impart temperature change on us
-	sharing_with_mutable.temperature += (-temperature_change_to_them * (their_effective_capacity / our_singular_heat_capacity)) / our_size_multiplier
+	// this is calculated with the energy imparted by their temperature change
+	// this is grouped in a specific way to avoid float imprecision!
+	sharing_with_mutable.temperature += -temperature_change_to_them * heat_capacity / sharing_with_mutable.group_multiplier * limit_ratio / our_singular_heat_capacity
 	// return temperature change to them
-	return temperature_change_to_them * (their_effective_capacity / heat_capacity)
+	return temperature_change_to_them * limit_ratio

code/modules/atmospherics/gasmixtures/gas_mixture-environmental.dm

@@ -12,7 +12,7 @@
  * based on connecting tiles. Is just a wrapper to use a lookup table.
  */
 /datum/gas_mixture/proc/environmental_share_simulated(datum/gas_mixture/other, tiles)
-#ifdef GASMIXTURE_ASSERTIONS
+#ifdef CF_ATMOS_DEBUG_ASSERTIONS
 	ASSERT(tiles > 0)
 #endif
 	var/static/list/lookup_table = list(

code/modules/atmospherics/gasmixtures/gas_mixture-share.dm

@@ -18,7 +18,7 @@
  * @return TRUE if we are near-equivalent to the other, FALSE if we are still different.
  */
 /datum/gas_mixture/proc/share_with_mixture(datum/gas_mixture/other, ratio)
-#ifdef GASMIXTURE_ASSERTIONS
+#ifdef CF_ATMOS_DEBUG_ASSERTIONS
 	ASSERT(ratio > 0 && ratio <= 1)
 	// todo: volume based, not group multiplier based. is it worth it?
 	ASSERT(volume == other.volume)
@@ -89,7 +89,7 @@
  * @return TRUE if we are near-equivalent to the other, FALSE if we are still different.
  */
 /datum/gas_mixture/proc/share_with_immutable(list/gases, group_multiplier, temperature, ratio)
-#ifdef GASMIXTURE_ASSERTIONS
+#ifdef CF_ATMOS_DEBUG_ASSERTIONS
 	ASSERT(ratio > 0 && ratio <= 1)
 	ASSERT(temperature >= TCMB)
 	ASSERT(group_multiplier >= 1)