Fix for whip/pike attack invisible but revealed enemies

changes/issue-516.md

@@ -0,0 +1,2 @@
+-
+  The whip, spear, and rapier now work against invisible enemies when you are telepathic.

src/brogue/Items.c

@@ -639,7 +639,7 @@ void populateItems(pos upstairs) {
         } else if (rogue.depthLevel > gameConst->amuletLevel) {
             theCategory = GEM;
         } else {
-            
+
             for (int j = 0; j < gameConst->numberMeteredItems; j++) {
                 // Create any metered items that reach generation thresholds
                 if (meteredItemsGenerationTable[j].levelScaling != 0 &&
@@ -3491,13 +3491,13 @@ void getImpactLoc(pos *returnLoc, const pos originLoc, const pos targetLoc,
     pos coords[DCOLS + 1];
     short i, n;
     creature *monst;
+    creature *orig = monsterAtLoc(originLoc);
 
     n = getLineCoordinates(coords, originLoc, targetLoc, theBolt);
     n = min(n, maxDistance);
     for (i=0; i<n; i++) {
         monst = monsterAtLoc(coords[i]);
-        if (monst
-            && !monsterIsHidden(monst, monsterAtLoc(originLoc))
+        if (canAttack(orig, monst)
             && !(monst->bookkeepingFlags & MB_SUBMERGED)) {
             // Imaginary bolt hit the player or a monster.
             break;

src/brogue/Monsters.c

@@ -231,6 +231,30 @@ boolean canDirectlySeeMonster(creature *monst) {
     return false;
 }
 
+// Centralize the logic of whether an attacker can/will attack the defender
+boolean canAttack( creature *attacker, creature *defender ) {
+    if (attacker == NULL || defender == NULL) return false;
+
+    // Must be enemies
+    boolean areEnemies = monsterWillAttackTarget(attacker, defender);
+
+    // Must be able to attack the cell where the defender is located
+    boolean canAttackCell = !cellHasTerrainFlag(defender->loc.x, defender->loc.y, T_OBSTRUCTS_PASSABILITY)
+                    || (defender->info.flags & MONST_ATTACKABLE_THRU_WALLS);
+
+    // Must be able to detect the defender
+    boolean locationKnown;
+    if (attacker == &player) {
+        locationKnown = canSeeMonster(defender) || monsterRevealed(defender);
+    } else {
+        // Monsters don't understand revealing.
+        locationKnown = !monsterIsHidden(defender, attacker);
+    }
+
+    // All three requirements must be met
+    return (areEnemies && canAttackCell && locationKnown);
+}
+
 void monsterName(char *buf, creature *monst, boolean includeArticle) {
     short oldRNG;
 

src/brogue/Movement.c

@@ -586,11 +586,8 @@ boolean handleWhipAttacks(creature *attacker, enum directions dir, boolean *abor
     getImpactLoc(&strikeLoc, originLoc, targetLoc, 5, false, &boltCatalog[BOLT_WHIP]);
 
     defender = monsterAtLoc(strikeLoc);
-    if (defender
-        && (attacker != &player || canSeeMonster(defender))
-        && !monsterIsHidden(defender, attacker)
-        && monsterWillAttackTarget(attacker, defender)) {
-
+    if (canAttack(attacker, defender)
+        && !(defender->bookkeepingFlags & MB_SUBMERGED)) {
         if (attacker == &player) {
             hitList[0] = defender;
             if (abortAttackAgainstAcidicTarget(hitList)) {
@@ -654,8 +651,7 @@ boolean handleSpearAttacks(creature *attacker, enum directions dir, boolean *abo
             /* We check if i=0, i.e. the defender is right next to us, because
             we have to do "normal" attacking here. We can't just return
             false and leave to playerMoves/moveMonster due to the collateral hitlist. */
-            if (i == 0 || !monsterIsHidden(defender, attacker)
-                && (attacker != &player || canSeeMonster(defender))) {
+            if (i == 0 || canAttack(attacker, defender)) {
                 // We'll attack.
                 proceed = true;
             }
@@ -722,11 +718,10 @@ void buildFlailHitList(const short x, const short y, const short newX, const sho
         my = monst->loc.y;
         if (distanceBetween((pos){x, y}, (pos){mx, my}) == 1
             && distanceBetween((pos){newX, newY}, (pos){mx, my}) == 1
-            && canSeeMonster(monst)
-            && monstersAreEnemies(&player, monst)
+            && canAttack(&player, monst)
             && monst->creatureState != MONSTER_ALLY
             && !(monst->bookkeepingFlags & MB_IS_DYING)
-            && (!cellHasTerrainFlag(monst->loc.x, monst->loc.y, T_OBSTRUCTS_PASSABILITY) || (monst->info.flags & MONST_ATTACKABLE_THRU_WALLS))) {
+            && canAttack(&player, monst)) {
 
             while (hitList[i]) {
                 i++;

src/brogue/Rogue.h

@@ -3170,6 +3170,7 @@ extern "C" {
     boolean monsterIsHidden(const creature *monst, const creature *observer);
     boolean canSeeMonster(creature *monst);
     boolean canDirectlySeeMonster(creature *monst);
+    boolean canAttack( creature *attacker, creature *defender );
     void monsterName(char *buf, creature *monst, boolean includeArticle);
     boolean monsterIsInClass(const creature *monst, const short monsterClass);
     boolean chooseTarget(pos *returnLoc, short maxDistance, boolean stopAtTarget, boolean autoTarget,