Make RFGL and RFRG a bit more realistic (#366)

* Make RFGL and RFRG a bit more realistic.

This means that they both more or less follow Gay-Lussac's law: T2 = T1 * P2 / P1. Simple heat transer mechanism, no playing around with .life, shared update function.

* Ditch weird pressure scale

* No /0 pls

src/simulation/elements/RFGL.cpp

@@ -27,66 +27,21 @@ Element_RFGL::Element_RFGL()
 	Weight = 10;
 
 	Temperature = R_TEMP + 273.15f;
-	HeatConduct = 0;
+	HeatConduct = 3;
 	Description = "Liquid refrigerant.";
 
 	Properties = TYPE_LIQUID|PROP_DEADLY;
 
-	LowPressure = IPL;
-	LowPressureTransition = NT;
+	LowPressure = 2;
+	LowPressureTransition = PT_RFRG;
 	HighPressure = IPH;
 	HighPressureTransition = NT;
 	LowTemperature = ITL;
 	LowTemperatureTransition = NT;
 	HighTemperature = ITH;
 	HighTemperatureTransition = NT;
 
-	Update = &Element_RFGL::update;
-}
-
-//#TPT-Directive ElementHeader Element_RFGL static int update(UPDATE_FUNC_ARGS)
-int Element_RFGL::update(UPDATE_FUNC_ARGS)
-{
-	float pressure = sim->pv[y/CELL][x/CELL];
-	if (pressure > parts[i].tmp)
-		parts[i].tmp = (int)pressure;
-
-	if (pressure > -1 && pressure < 15 && parts[i].life > 0)
-		parts[i].life --;
-
-	if (parts[i].temp >= 363.15f + (pressure * 6.0f))
-		sim->part_change_type(i, x, y, PT_RFRG);
-
-	int r, rx, ry;
-	for (rx=-1; rx<2; rx++)
-		for (ry=-1; ry<2; ry++)
-			if (BOUNDS_CHECK && (rx || ry))
-			{
-				r = pmap[y+ry][x+rx];
-				if (!r)
-					continue;
-				if ((r&0xFF) == PT_RFGL || (r&0xFF) == PT_RFRG)
-				{
-					float avgTemp = (parts[r>>8].temp + parts[i].temp) / 2;
-					parts[r>>8].temp = avgTemp;
-					parts[i].temp = avgTemp;
-				}
-				else
-				{
-					if (pressure > 20 && parts[i].temp > 273.15f + 2.0f - (pressure - 20.0f) && sim->elements[r&0xFF].HeatConduct)
-					{
-						parts[r>>8].temp = restrict_flt(parts[r>>8].temp + 80.0f, 0.0f, MAX_TEMP);
-						parts[i].temp = restrict_flt(parts[i].temp - 80.0f, 0.0f, MAX_TEMP);
-					}
-					else if (parts[i].life == 0 && parts[r>>8].temp > 273.15f - 50.0f - (parts[i].tmp - 20.0f) && sim->elements[r&0xFF].HeatConduct)
-					{
-						parts[r>>8].temp = restrict_flt(parts[r>>8].temp - 80.0f, 273.15f - 50.0f - (parts[i].tmp - 20.0f), MAX_TEMP);
-						parts[i].temp = restrict_flt(parts[i].temp + 80.0f, 0.0f, 383.15f);
-					}
-				}
-			}
-
-	return 0;
+	Update = &Element_RFRG::update;
 }
 
 Element_RFGL::~Element_RFGL() {}

src/simulation/elements/RFRG.cpp

@@ -28,14 +28,14 @@ Element_RFRG::Element_RFRG()
 
 	Temperature = R_TEMP + 273.15f;
 	HeatConduct = 3;
-	Description = "Refrigerant. Liquifies and transfers heat to other particles under pressure.";
+	Description = "Refrigerant. Heats up and liquifies under pressure.";
 
 	Properties = TYPE_GAS|PROP_DEADLY;
 
 	LowPressure = IPL;
 	LowPressureTransition = NT;
-	HighPressure = IPH;
-	HighPressureTransition = NT;
+	HighPressure = 2;
+	HighPressureTransition = PT_RFGL;
 	LowTemperature = ITL;
 	LowTemperatureTransition = NT;
 	HighTemperature = ITH;
@@ -47,16 +47,15 @@ Element_RFRG::Element_RFRG()
 //#TPT-Directive ElementHeader Element_RFRG static int update(UPDATE_FUNC_ARGS)
 int Element_RFRG::update(UPDATE_FUNC_ARGS)
 {
-	if (sim->pv[y/CELL][x/CELL] > 15)
-	{
-		parts[i].temp += (sim->pv[y/CELL][x/CELL] - 15.0f) / 2.0f;
-		if (parts[i].temp >= 343.15f)
-		{
-			sim->part_change_type(i, x, y, PT_RFGL);
-			parts[i].life = 20;
-		}
-	}
-
+	float new_pressure = sim->pv[y/CELL][x/CELL];
+	float *old_pressure = (float *)&parts[i].tmp;
+
+	// * 0 bar seems to be pressure value -256 in TPT, see Air.cpp. Also, 1 bar seems to be pressure value 0.
+	//   With those two values we can set up our pressure scale which states that ... the highest pressure
+	//   we can achieve in TPT is 2 bar. That's not particularly realistic, but good enough for TPT.
+
+	parts[i].temp = restrict_flt(parts[i].temp * ((new_pressure + 257.f) / (*old_pressure + 257.f)), 0, MAX_TEMP);
+	*old_pressure = new_pressure;
 	return 0;
 }