Allow TUNG melting point to be changed from Lua

Also set lava LowTemperature threshold to MAX_TEMP, to simplify changing melting points from Lua.

src/simulation/Simulation.cpp

@@ -3618,7 +3618,9 @@ void Simulation::UpdateParticles(int start, int end)
 									s = 0;
 								else if (parts[i].ctype==PT_TUNG)
 								{
-									if (pt>=3695.0)
+									// TUNG does its own melting in its update function, so HighTemperatureTransition is not LAVA so it won't be handled by the code for HighTemperatureTransition==PT_LAVA below
+									// However, the threshold is stored in HighTemperature to allow it to be changed from Lua
+									if (pt>=elements[parts[i].ctype].HighTemperature)
 										s = 0;
 								}
 								else if (elements[parts[i].ctype].HighTemperatureTransition == PT_LAVA)

src/simulation/elements/LAVA.cpp

@@ -37,7 +37,7 @@ Element_LAVA::Element_LAVA()
 	LowPressureTransition = NT;
 	HighPressure = IPH;
 	HighPressureTransition = NT;
-	LowTemperature = 3695.0f;// Highest temperature at which any type of lava can solidify
+	LowTemperature = MAX_TEMP;// check for lava solidification at all temperatures
 	LowTemperatureTransition = ST;
 	HighTemperature = ITH;
 	HighTemperatureTransition = NT;

src/simulation/elements/TUNG.cpp

@@ -40,22 +40,20 @@ Element_TUNG::Element_TUNG()
 	HighPressureTransition = NT;
 	LowTemperature = ITL;
 	LowTemperatureTransition = NT;
-	HighTemperature = ITH;
+	HighTemperature = 3695.0f;// TUNG melts in its update function instead of in the normal way, but store the threshold here so that it can be changed from Lua
 	HighTemperatureTransition = NT;
-	/*HighTemperature = 3895.0f;
-	HighTemperatureTransition = PT_LAVA;*/
 
 	Update = &Element_TUNG::update;
 	Graphics = &Element_TUNG::graphics;
 
 }
 
-#define MELTING_POINT	3695.0
-
 //#TPT-Directive ElementHeader Element_TUNG static int update(UPDATE_FUNC_ARGS)
 int Element_TUNG::update(UPDATE_FUNC_ARGS)
 {
 	bool splode = false;
+	const float MELTING_POINT = sim->elements[PT_TUNG].HighTemperature;
+
 	if(parts[i].temp > 2400.0)
 	{
 		int r, rx, ry;
@@ -90,7 +88,7 @@ int Element_TUNG::update(UPDATE_FUNC_ARGS)
 		}
 		if(splode)
 		{
-			parts[i].temp = MELTING_POINT + (rand()%600) + 200;
+			parts[i].temp = restrict_flt(MELTING_POINT + (rand()%600) + 200, MIN_TEMP, MAX_TEMP);
 		}
 		parts[i].vx += (rand()%100)-50;
 		parts[i].vy += (rand()%100)-50;
@@ -111,6 +109,7 @@ int Element_TUNG::update(UPDATE_FUNC_ARGS)
 //#TPT-Directive ElementHeader Element_TUNG static int graphics(GRAPHICS_FUNC_ARGS)
 int Element_TUNG::graphics(GRAPHICS_FUNC_ARGS)
 {
+	const float MELTING_POINT = ren->sim->elements[PT_TUNG].HighTemperature;
 	double startTemp = (MELTING_POINT - 1500.0);
 	double tempOver = (((cpart->temp - startTemp)/1500.0)*M_PI) - (M_PI/2.0);
 	if(tempOver > -(M_PI/2.0))