power: Also calculate the construction ETA.

This ETA of course depends on the number of trucks helping with construction.

src/droid.cpp

@@ -1137,7 +1137,7 @@ bool droidUpdateBuild(DROID *psDroid)
 	pointsToAdd = constructPoints * (gameTime - psDroid->actionStarted) /
 		GAME_TICKS_PER_SEC;
 
-	structureBuild(psStruct, psDroid, pointsToAdd - psDroid->actionPoints);
+	structureBuild(psStruct, psDroid, pointsToAdd - psDroid->actionPoints, constructPoints);
 
 	//store the amount just added
 	psDroid->actionPoints = pointsToAdd;

src/intdisplay.cpp

@@ -227,7 +227,12 @@ void intUpdateProgressBar(WIDGET *psWidget, W_CONTEXT *psContext)
 					}
 					else
 					{
-						BarGraph->text.clear();  // TODO Hard to estimate time remaining, since number of trucks can vary.
+						BarGraph->text.clear();
+						if (Structure->lastBuildRate > 0)
+						{
+							int timeToBuild = (Structure->pStructureType->buildPoints - Structure->currentBuildPts) / Structure->lastBuildRate;
+							BarGraph->text = formatTime(timeToBuild);
+						}
 					}
 
 					if (BuildPoints > Range)

src/structure.cpp

@@ -866,7 +866,7 @@ int32_t getStructureDamage(const STRUCTURE *psStructure)
 
 /// Add buildPoints to the structures currentBuildPts, due to construction work by the droid
 /// Also can deconstruct (demolish) a building if passed negative buildpoints
-void structureBuild(STRUCTURE *psStruct, DROID *psDroid, int buildPoints)
+void structureBuild(STRUCTURE *psStruct, DROID *psDroid, int buildPoints, int buildRate)
 {
 	if (psDroid && !aiCheckAlliances(psStruct->player,psDroid->player))
 	{
@@ -888,7 +888,7 @@ void structureBuild(STRUCTURE *psStruct, DROID *psDroid, int buildPoints)
 			}
 		}
 	}
-	psStruct->builtThisTick = true;
+	psStruct->buildRate += buildRate;  // buildRate = buildPoints/GAME_UPDATES_PER_SEC, but might be rounded up or down each tick, so can't use buildPoints to get a stable number.
 	if (psStruct->currentBuildPts <= 0 && buildPoints > 0)
 	{
 		// Just starting to build structure, need power for it.
@@ -1845,7 +1845,7 @@ STRUCTURE* buildStructureDir(STRUCTURE_STATS *pStructureType, UDWORD x, UDWORD y
 			psBuilding->currentBuildPts = 0;
 			//start building again
 			psBuilding->status = SS_BEING_BUILT;
-			psBuilding->builtThisTick = true;  // Don't abandon the structure first tick.
+			psBuilding->buildRate = 1;  // Don't abandon the structure first tick, so set to nonzero.
 			if (psBuilding->player == selectedPlayer && !FromSave)
 			{
 				intRefreshScreen();
@@ -3737,11 +3737,12 @@ void structureUpdate(STRUCTURE *psBuilding, bool mission)
 		}
 	}
 
-	if (psBuilding->status == SS_BEING_BUILT && psBuilding->currentBuildPts == 0 && !psBuilding->builtThisTick && !structureHasModules(psBuilding))
+	if (psBuilding->status == SS_BEING_BUILT && psBuilding->currentBuildPts == 0 && psBuilding->buildRate == 0 && !structureHasModules(psBuilding))
 	{
 		removeStruct(psBuilding, true);  // If giving up on building something, remove the structure (and remove it from the power queue).
 	}
-	psBuilding->builtThisTick = false;
+	psBuilding->lastBuildRate = psBuilding->buildRate;
+	psBuilding->buildRate = 0;  // Reset to 0, each truck building us will add to our buildRate.
 
 	/* Only add smoke if they're visible and they can 'burn' */
 	if (!mission && psBuilding->visible[selectedPlayer] && canSmoke(psBuilding))
@@ -3874,7 +3875,8 @@ void structureUpdate(STRUCTURE *psBuilding, bool mission)
 STRUCTURE::STRUCTURE(uint32_t id, unsigned player)
 	: BASE_OBJECT(OBJ_STRUCTURE, id, player)
 	, pFunctionality(NULL)
-	, builtThisTick(true)
+	, buildRate(1)  // Initialise to 1 instead of 0, to make sure we don't get destroyed first tick due to inactivity.
+	, lastBuildRate(0)
 	, psCurAnim(NULL)
 {}
 

src/structure.h

@@ -113,7 +113,7 @@ extern bool	structureStatsShutDown(void);
 int requestOpenGate(STRUCTURE *psStructure);
 
 int32_t structureDamage(STRUCTURE *psStructure, UDWORD damage, WEAPON_CLASS weaponClass, WEAPON_SUBCLASS weaponSubClass, HIT_SIDE impactSide);
-extern void structureBuild(STRUCTURE *psStructure, DROID *psDroid, int buildPoints);
+extern void structureBuild(STRUCTURE *psStructure, DROID *psDroid, int buildPoints, int buildRate = 1);
 extern void structureDemolish(STRUCTURE *psStructure, DROID *psDroid, int buildPoints);
 extern bool structureRepair(STRUCTURE *psStruct, DROID *psDroid, int buildPoints);
 /* Set the type of droid for a factory to build */

src/structuredef.h

@@ -253,7 +253,8 @@ struct STRUCTURE : public BASE_OBJECT
 	SWORD               resistance;                 /* current resistance points, 0 = cannot be attacked electrically */
 	UDWORD              lastResistance;             /* time the resistance was last increased*/
 	FUNCTIONALITY       *pFunctionality;            /* pointer to structure that contains fields necessary for functionality */
-	bool                builtThisTick;              ///< True iff someone tried building the structure this tick. If construction hasn't started, remove the structure.
+	int                 buildRate;                  ///< Rate that this structure is being built, calculated each tick. Only meaningful if status == SS_BEING_BUILT. If construction hasn't started and build rate is 0, remove the structure.
+	int                 lastBuildRate;              ///< Needed if wanting the buildRate between buildRate being reset to 0 each tick and the trucks calculating it.
 
 	/* The weapons on the structure */
 	UWORD		numWeaps;