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Stop ship and land unit movement on interdiction with no damage

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Movement stops when shp_interdict() or lnd_interdict() report
interdiction.  However, they reported it only when there was
interdiction damage.

Zero interdiction damage commonly happens when interdicting missiles
miss, or all bombers abort.  Stopping regardless of damage makes more
sense there.

Moreover, not stopping is buggy: do_unit_move() needs to take care not
to wipe out updates made by interdiction to the moving ships or land
units.  It does so only when it stops.  Updates made by interdiction
without interdiction damage could get wiped out, triggering a seqno
mismatch oops.

Known ways moving ships and land units can get updated by interdiction
despite there is no interdiction damage:

* Interdicting bombers get intercepted by planes based on a navigating
  carrier, carrier gets charged petrol.  The bug wipes out the petrol
  use.

* Marching land units get interdicted by planes, but all planes miss.
  Sufficiently large collateral damage to the sector can still damage
  the land units.  The bug wipes out the damage to land units.

To make shp_interdict() and lnd_interdict() report interdiction
regardless of damage, change lnd_missile_interdiction(),
lnd_fort_interdiction(), lnd_mission_interdiction(),
shp_missile_interdiction(), shp_fort_interdiction(),
shp_mission_interdiction() to return whether there was interdiction.
Before, they returned whether there was damage.

Change unit_interdict(), perform_mission(), perform_mission_land(),
perform_mission_ship(), perform_mission_msl(), and
perform_mission_bomb() to return -1 for no interdiction, so that
callers can distinguish no interdiction from interdiction with no
damage.
This commit is contained in:
Markus Armbruster 2010-01-09 16:21:40 +01:00
parent 05b56fa942
commit 227854bca2
3 changed files with 62 additions and 45 deletions
Download patch file Download diff file Expand all files Collapse all files

23
src/lib/subs/lndsub.c
View file

@ -721,6 +721,7 @@ lnd_missile_interdiction(struct emp_qelem *list, coord newx, coord newy,
int mindam = lnd_count(list) * 20;
int hardtarget = lnd_easiest_target(list);
int dam, newdam, sublaunch;
int stopping = 0;
struct plist *plp;
struct emp_qelem msl_list, *qp, *newqp;
@ -735,6 +736,7 @@ lnd_missile_interdiction(struct emp_qelem *list, coord newx, coord newy,
if (msl_launch(&plp->plane, EF_LAND, "troops",
newx, newy, victim, &sublaunch) < 0)
goto use_up_msl;
stopping = 1;
if (msl_hit(&plp->plane, hardtarget, EF_LAND,
N_LND_MISS, N_LND_SMISS, sublaunch, victim)) {
newdam = pln_damage(&plp->plane, 'p', 1);
@ -754,8 +756,9 @@ lnd_missile_interdiction(struct emp_qelem *list, coord newx, coord newy,
if (dam) {
mpr(victim, "missile interdiction mission does %d damage!\n", dam);
collateral_damage(newx, newy, dam);
lnd_damage(list, dam);
}
return lnd_damage(list, dam);
return stopping;
}
#if 0
@ -771,6 +774,7 @@ lnd_fort_interdiction(struct emp_qelem *list,
double guneff;
int shell, gun;
int dam;
int stopping = 0;
int totdam = 0;
int i;
@ -790,6 +794,7 @@ lnd_fort_interdiction(struct emp_qelem *list,
putsect(&fsect);
if (dam < 0)
continue;
stopping = 1;
totdam += dam;
mpr(victim, "Incoming fire does %d damage!\n", dam);
wu(0, fsect.sct_own,
@ -800,8 +805,8 @@ lnd_fort_interdiction(struct emp_qelem *list,
nreport(fsect.sct_own, N_SCT_SHELL, victim, 1);
}
if (totdam > 0)
return lnd_damage(list, totdam);
return 0;
lnd_damage(list, totdam);
return stopping;
}
#endif
@ -809,10 +814,14 @@ static int
lnd_mission_interdiction(struct emp_qelem *list, coord x, coord y,
natid victim)
{
return lnd_damage(list,
unit_interdict(x, y, victim, "land units",
lnd_easiest_target(list),
MI_INTERDICT));
int dam;
dam = unit_interdict(x, y, victim, "land units",
lnd_easiest_target(list),
MI_INTERDICT);
if (dam >= 0)
lnd_damage(list, dam);
return dam >= 0;
}
int