Fix mirrored totem beckoning sometimes instakilling the player (tmewe…

…tt#498) This fixes the issue by reversing the bolt direction for the blinking triggered by beckoning, by swapping the bolt origin and target and then reversing the resulting list. This also makes the same adjustment to the behavior of wands of beckoning. This seems to make the wand's behavior more closely match what you'd expect from the path displayed when targeting it. For instance, it makes it easier to target enemies that are behind other enemies.
pdpol · Jan 16, 2023 · 1505d71 · 1505d71
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commit 1505d71
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Showing 6 changed files with 38 additions and 9 deletions.
diff --git a/changes/beckoning.md b/changes/beckoning.md
@@ -0,0 +1 @@
+Fixed that mirrored totem beckoning could instakill the player in some situations, and modified the wand of beckoning to more easily target enemies behind obstacles.
diff --git a/src/brogue/Combat.c b/src/brogue/Combat.c
@@ -508,7 +508,7 @@ boolean forceWeaponHit(creature *defender, item *theItem) {
     }
     theBolt = boltCatalog[BOLT_BLINKING];
     theBolt.magnitude = max(1, netEnchant(theItem) / FP_FACTOR);
-    zap(oldLoc, newLoc, &theBolt, false);
+    zap(oldLoc, newLoc, &theBolt, false, false);
     if (!(defender->bookkeepingFlags & MB_IS_DYING)
         && distanceBetween(oldLoc.x, oldLoc.y, defender->loc.x, defender->loc.y) > 0
         && distanceBetween(oldLoc.x, oldLoc.y, defender->loc.x, defender->loc.y) < weaponForceDistance(netEnchant(theItem))) {

diff --git a/src/brogue/Items.c b/src/brogue/Items.c
@@ -4241,7 +4241,7 @@ void beckonMonster(creature *monst, short x, short y) {
     pos from = monst->loc;
     pos to = (pos){ .x = x, .y = y };
     theBolt.magnitude = max(1, (distanceBetween(x, y, monst->loc.x, monst->loc.y) - 2) / 2);
-    zap(from, to, &theBolt, false);
+    zap(from, to, &theBolt, false, true);
     if (monst->ticksUntilTurn < player.attackSpeed+1) {
         monst->ticksUntilTurn = player.attackSpeed+1;
     }
@@ -4713,7 +4713,7 @@ void detonateBolt(bolt *theBolt, creature *caster, short x, short y, boolean *au
 }
 
 // returns whether the bolt effect should autoID any staff or wand it came from, if it came from a staff or wand
-boolean zap(pos originLoc, pos targetLoc, bolt *theBolt, boolean hideDetails) {
+boolean zap(pos originLoc, pos targetLoc, bolt *theBolt, boolean hideDetails, boolean reverseBoltDir) {
     pos listOfCoordinates[MAX_BOLT_LENGTH];
     short i, j, k, x, y, x2, y2, numCells, blinkDistance = 0, boltLength, initialBoltLength, lights[DCOLS][DROWS][3];
     creature *monst = NULL, *shootingMonst;
@@ -4741,7 +4741,34 @@ boolean zap(pos originLoc, pos targetLoc, bolt *theBolt, boolean hideDetails) {
     y = originLoc.y;
 
     initialBoltLength = boltLength = 5 * theBolt->magnitude;
-    numCells = getLineCoordinates(listOfCoordinates, originLoc, targetLoc, (hideDetails ? &boltCatalog[BOLT_NONE] : theBolt));
+    if (reverseBoltDir) {
+        // Beckoning (from mirrored totems and the wand) is implemented as two bolts, one going from
+        // the totem/player to the target, and another from the target back to the source, to blink
+        // them adjacent. However, bolt paths are asymmetric; the path from A to B isn't necessarily
+        // the same as the path from B to A. If the second bolt (the blink) follows a different
+        // path, it's possible for the target not to be blinked all the way back to the source
+        // because it hits an obstacle (usually a monster). This results in issue #497, as well as
+        // unintuitive behavior for the wand of beckoning. As a workaround, for the second bolt, we
+        // compute it as if it went from the source to the target, and then reverse the list of
+        // coordinates. This ensures that the two bolts will include exactly the same coordinates,
+        // so the target won't get stuck on any obstacles while being beckoned.
+        pos listOfCoordinatesTmp[MAX_BOLT_LENGTH];
+        short numCellsTmp = getLineCoordinates(listOfCoordinatesTmp, targetLoc, originLoc, (hideDetails ? &boltCatalog[BOLT_NONE] : theBolt));
+        numCells = -1;
+        for (int i = 0; i < numCellsTmp; i++) {
+            if (listOfCoordinatesTmp[i].x == originLoc.x && listOfCoordinatesTmp[i].y == originLoc.y) {
+                numCells = i+1;
+                break;
+            }
+        }
+        brogueAssert(numCells > -1);
+        for (int i = 0; i < numCells-1; i++) {
+            listOfCoordinates[i] = listOfCoordinatesTmp[numCells-2-i];
+        }
+        listOfCoordinates[numCells-1] = targetLoc;
+    } else {
+        numCells = getLineCoordinates(listOfCoordinates, originLoc, targetLoc, (hideDetails ? &boltCatalog[BOLT_NONE] : theBolt));
+    }
     shootingMonst = monsterAtLoc(originLoc.x, originLoc.y);
 
     if (hideDetails) {
@@ -6412,7 +6439,8 @@ boolean useStaffOrWand(item *theItem, boolean *commandsRecorded) {
         if (theItem->charges > 0) {
             autoID = zap(originLoc, zapTarget,
                          &theBolt,
-                         !boltKnown);   // hide bolt details
+                         !boltKnown,   // hide bolt details
+                         false);
             if (autoID) {
                 if (!tableForItemCategory(theItem->category)[theItem->kind].identified) {
                     itemName(theItem, buf2, false, false, NULL);

diff --git a/src/brogue/Monsters.c b/src/brogue/Monsters.c
@@ -2339,7 +2339,7 @@ boolean monsterBlinkToPreferenceMap(creature *monst, short **preferenceMap, bool
         }
         monst->ticksUntilTurn = monst->attackSpeed * (monst->info.flags & MONST_CAST_SPELLS_SLOWLY ? 2 : 1);
         theBolt = boltCatalog[theBoltType];
-        zap(origin, bestTarget, &theBolt, false);
+        zap(origin, bestTarget, &theBolt, false, false);
         return true;
     }
     return false;
@@ -2677,7 +2677,7 @@ void monsterCastSpell(creature *caster, creature *target, enum boltType boltInde
     theBolt = boltCatalog[boltIndex];
     pos originLoc = caster->loc;
     pos targetLoc = target->loc;
-    zap(originLoc, targetLoc, &theBolt, false);
+    zap(originLoc, targetLoc, &theBolt, false, false);
 
     if (player.currentHP <= 0) {
         gameOver(monsterCatalog[caster->info.monsterID].monsterName, false);

diff --git a/src/brogue/Movement.c b/src/brogue/Movement.c
@@ -613,7 +613,7 @@ boolean handleWhipAttacks(creature *attacker, enum directions dir, boolean *abor
         attacker->bookkeepingFlags &= ~MB_SUBMERGED;
         theBolt = boltCatalog[BOLT_WHIP];
         theBolt.theChar = boltChar[dir];
-        zap(originLoc, targetLoc, &theBolt, false);
+        zap(originLoc, targetLoc, &theBolt, false, false);
         return true;
     }
     return false;

diff --git a/src/brogue/Rogue.h b/src/brogue/Rogue.h
@@ -3062,7 +3062,7 @@ extern "C" {
     void checkForMissingKeys(short x, short y);
     enum boltEffects boltEffectForItem(item *theItem);
     enum boltType boltForItem(item *theItem);
-    boolean zap(pos originLoc, pos targetLoc, bolt *theBolt, boolean hideDetails);
+    boolean zap(pos originLoc, pos targetLoc, bolt *theBolt, boolean hideDetails, boolean reverseBoltDir);
     boolean nextTargetAfter(short *returnX,
                             short *returnY,
                             short targetX,
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		Fixed that mirrored totem beckoning could instakill the player in some situations, and modified the wand of beckoning to more easily target enemies behind obstacles.