cpp/openttd-patchpack/source Changeset - r12227:937c28c992ae

Changeset - r12227:937c28c992ae

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smatz - 15 years ago 2009-06-24 23:59:20
smatz@openttd.org

(svn r16652) -Codechange: use less strict, but faster check for quickly bailing out in FindTrainCollideEnum() (Bilbo)
-Codechange: shuffle the code a bit

1 file changed with 40 insertions and 37 deletions:

src/train_cmd.cpp

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src/train_cmd.cpp

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@@ @@ -3530,6 +3530,16 @@ static uint CountPassengersInTrain(const @@
  */
 static uint TrainCrashed(Train *v)
+{
 	/* Try to re-reserve track under already crashed train too */
 	for (const Train *u = v; u != NULL; u = u->Next()) {
 		TrackBits trackbits = u->track;
 		if (trackbits == TRACK_BIT_WORMHOLE) {
 			/* Vehicle is inside a wormhole, v->track contains no useful value then. */
 			trackbits = DiagDirToDiagTrackBits(GetTunnelBridgeDirection(u->tile));
+		}
 		TryReserveRailTrack(u->tile, TrackBitsToTrack(trackbits));
+	}
 	/* do not crash train twice */
 	if (v->vehstatus & VS_CRASHED) return 0;
@@ @@ -3543,51 +3553,44 @@ static uint TrainCrashed(Train *v) @@
+}
 struct TrainCollideChecker {
 	Vehicle *v;  ///< vehicle we are testing for collision
 	uint num;    ///< number of dead if train collided
 	Train *v; ///< vehicle we are testing for collision
 	uint num; ///< number of victims if train collided
 };
 static Vehicle *FindTrainCollideEnum(Vehicle *v, void *data)
+{
 	TrainCollideChecker *tcc = (TrainCollideChecker*)data;
 	if (v->type != VEH_TRAIN) return NULL;
 	/* not a train or in depot */
 	if (v->type != VEH_TRAIN || Train::From(v)->track == TRACK_BIT_DEPOT) return NULL;
 	/* get first vehicle now to make most usual checks faster */
 	Vehicle *coll = v->First();
 	/* can't collide with own wagons && can't crash in depot && the same height level */
 	if (coll != tcc->v && Train::From(v)->track != TRACK_BIT_DEPOT && abs(v->z_pos - tcc->v->z_pos) < 6) {
 		int x_diff = v->x_pos - tcc->v->x_pos;
 		int y_diff = v->y_pos - tcc->v->y_pos;
 		/* Needed to disable possible crash of competitor train in station by building diagonal track at its end.
 		 * The second check is false when (abs(first), abs(second)) is: a) 5, 0  b) 4, <=3  c) 3, <=4, d) 2-, <=5
 		 * Sum of these two is at most 2 + 5 == 4 + 3 == 7. So we can just test if sum of abs() is > 7 to prevent
 		 * multiplying. Simply, when sum of abs() is >= 8, the sum of squares can't be <= 25.
 		 * Even gcc3.4 seems to do abs() branchless (using arithmetics or conditional moves). */
 		if (abs(x_diff) + abs(y_diff) > 7 || x_diff * x_diff + y_diff * y_diff > 25) return NULL;
 		/* crash both trains */
 		tcc->num += TrainCrashed(Train::From(tcc->v));
 		tcc->num += TrainCrashed(Train::From(coll));
 		/* Try to reserve all tiles directly under the crashed trains.
 		 * As there might be more than two trains involved, we have to do that for all vehicles */
 		const Train *u;
 		FOR_ALL_TRAINS(u) {
 			if ((u->vehstatus & VS_CRASHED) && u->track != TRACK_BIT_DEPOT) {
 				TrackBits trackbits = u->track;
 				if (trackbits == TRACK_BIT_WORMHOLE) {
 					/* Vehicle is inside a wormhole, v->track contains no useful value then. */
 					trackbits = DiagDirToDiagTrackBits(GetTunnelBridgeDirection(u->tile));
+				}
 				TryReserveRailTrack(u->tile, TrackBitsToTrack(trackbits));
+			}
+		}
+	}
 	return NULL;
 	Train *coll = Train::From(v)->First();
 	/* can't collide with own wagons */
 	if (coll == tcc->v) return NULL;
 	int x_diff = v->x_pos - tcc->v->x_pos;
 	int y_diff = v->y_pos - tcc->v->y_pos;
 	/* Do fast calculation to check whether trains are not in close vicinity
 	 * and quickly reject trains distant enough for any collision.
 	 * Differences are shifted by 7, mapping range [-7 .. 8] into [0 .. 15]
 	 * Differences are then ORed and then we check for any higher bits */
 	uint hash = (y_diff + 7) | (x_diff + 7);
 	if (hash & ~15) return NULL;
 	/* Slower check using multiplication */
 	if (x_diff * x_diff + y_diff * y_diff > 25) return NULL;
 	/* Happens when there is a train under bridge next to bridge head */
 	if (abs(v->z_pos - tcc->v->z_pos) > 5) return NULL;
 	/* crash both trains */
 	tcc->num += TrainCrashed(tcc->v);
 	tcc->num += TrainCrashed(coll);
 	return NULL; // continue searching
+}
 /**

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