Fix pavg loading behaviour of QRTZ/GLAS/TUNG (fixes #607)

Those particles now save/load pavg if pressure is being saved/loaded.
This means they won't ever break again when being loaded as part of
a stamp.

They actually save pavg01 * 64 because pavg is saved as an integer and
these elements are too sensitive to pressure changes for integer pavg
values to be adequate.

src/client/GameSave.cpp

@@ -2254,14 +2254,37 @@ char * GameSave::serialiseOPS(unsigned int & dataLength)
 				}
 
 				//Pavg, 4 bytes
-				//Don't save pavg for things that break under pressure, because then they will break when the save is loaded, since pressure isn't also loaded
-				if ((particles[i].pavg[0] || particles[i].pavg[1]) && !(particles[i].type == PT_QRTZ || particles[i].type == PT_GLAS || particles[i].type == PT_TUNG))
+				// save pavg if there's useful pavg to save
+				// and either we save pressure data too
+				// or the current particle is not one that cares about pressure
+				if (particles[i].pavg[0] || particles[i].pavg[1])
 				{
-					fieldDesc |= 1 << 13;
-					partsData[partsDataLen++] = (int)particles[i].pavg[0];
-					partsData[partsDataLen++] = ((int)particles[i].pavg[0])>>8;
-					partsData[partsDataLen++] = (int)particles[i].pavg[1];
-					partsData[partsDataLen++] = ((int)particles[i].pavg[1])>>8;
+					float pavg0 = particles[i].pavg[0];
+					float pavg1 = particles[i].pavg[1];
+					switch (particles[i].type)
+					{
+						// List of elements that save pavg with a multiplicative bias of 2**6
+						// (or not at all if pressure is not saved).
+						// If you change this list, change it in Simulation::Load too!
+					case PT_QRTZ:
+					case PT_GLAS:
+					case PT_TUNG:
+						if (!hasPressure)
+						{
+							break;
+						}
+						pavg0 *= 64;
+						pavg1 *= 64;
+						// fallthrough!
+
+					default:
+						fieldDesc |= 1 << 13;
+						partsData[partsDataLen++] = (int)pavg0;
+						partsData[partsDataLen++] = ((int)pavg0)>>8;
+						partsData[partsDataLen++] = (int)pavg1;
+						partsData[partsDataLen++] = ((int)pavg1)>>8;
+						break;
+					}
 				}
 
 				//Write the field descriptor

src/simulation/Simulation.cpp

@@ -233,6 +233,24 @@ int Simulation::Load(int fullX, int fullY, GameSave * save, bool includePressure
 		case PT_SOAP:
 			soapList.insert(std::pair<unsigned int, unsigned int>(n, i));
 			break;
+
+			// List of elements that load pavg with a multiplicative bias of 2**6
+			// (or not at all if pressure is not loaded).
+			// If you change this list, change it in GameSave::serialiseOPS too!
+		case PT_QRTZ:
+		case PT_GLAS:
+		case PT_TUNG:
+			if (!includePressure)
+			{
+				parts[i].pavg[0] = 0;
+				parts[i].pavg[1] = 0;
+			}
+			else
+			{
+				parts[i].pavg[0] /= 64;
+				parts[i].pavg[1] /= 64;
+			}
+			break;
 		}
 	}
 	parts_lastActiveIndex = NPART-1;
@@ -437,11 +455,14 @@ GameSave * Simulation::Save(int fullX, int fullY, int fullX2, int fullY2, bool i
 				newSave->velocityX[saveBlockY][saveBlockX] = vx[saveBlockY+blockY][saveBlockX+blockX];
 				newSave->velocityY[saveBlockY][saveBlockX] = vy[saveBlockY+blockY][saveBlockX+blockX];
 				newSave->ambientHeat[saveBlockY][saveBlockX] = hv[saveBlockY+blockY][saveBlockX+blockX];
-				newSave->hasPressure = true;
-				newSave->hasAmbientHeat = true;
 			}
 		}
 	}
+	if (includePressure)
+	{
+		newSave->hasPressure = true;
+		newSave->hasAmbientHeat = true;
+	}
 
 	newSave->stkm.rocketBoots1 = player.rocketBoots;
 	newSave->stkm.rocketBoots2 = player2.rocketBoots;