Fix: portal to quest would sometimes not spawn if entry portal spawned on Aphrodite's Garden or the Desolate Forest levels.

This was a weird one, initially caught while fuzzing. This started out
as an issue with a gold vault spawning on either Aphrodite's garden
level or the desolate forest level, and that vault being chosen to spawn
a portal to Fort Ludios. Fixed that (I think 😁) and then noticed some
more weirdness with the number of rooms spawning on those levels not
being as high as they should be. One thing led to another, discovered I
did not have to have a special ordinary room spawn on either of those
special levels, a portal to the quest could generate just fine without
it. Then started to see 'portal on top of portal??' impossible messages
when a quest portal would spawn on those special levels - sometimes, but
not all the time.

This meant there was a non-zero chance that the game could become
unwinnable under certain, albeit rare, conditions. This went from a
nuicance during fuzzing to a serious issue.

Took a bit of doing, but terrapin and I narrowed it down to some issues
in the somexyspace() function. Discovered that the creation of grass in
those special level rooms would mess with portal generation. Added a
couple exclusions for grass (and sand while there), and while poking
around in somexyspace(), noticed that the check for (xy_flags & 2) was
slightly wrong, and had been this way for a looooong time.

So long story short - fixed quest portal placement for those special
levels, normal rooms are no longer required there, fixed somexyspace().

I need a drink.

Co-authored-by: saltwaterterrapin <[email protected]>

Author: k21971

dat/forest.des

@@ -36,7 +36,7 @@ OBJECT:random, random
 }
 
 # normal room, in case of branch portal/stairs placement
-ROOM: "ordinary", random, random, random, random
+ROOM: "forest", random, random, random, random
 {
 [30%]:TERRAIN:random, 't'
 [30%]:TERRAIN:random, 't'

dat/nymph.des

@@ -63,7 +63,7 @@ OBJECT:random, random
 }
 
 # normal room, in case of branch portal/stairs placement
-ROOM: "ordinary", random, random, random, random
+ROOM: "garden", random, random, random, random
 {
 [30%]:TERRAIN:random, 'T'
 [30%]:TERRAIN:random, 'T'

doc/evilhack-changelog.md

@@ -4360,4 +4360,6 @@ The following changes to date are:
 - Fix: impossible "trying to break non-equipped glass obj?" when
   attacking with certain objects
 - Fix: grammar feedback when spells like barkskin or stoneskin wear off
+- Fix: portal to quest would sometimes not spawn if entry portal spawned
+  on Aphrodite's Garden or the Desolate Forest levels
 

src/mklev.c

@@ -1342,9 +1342,7 @@ coord *mp;
 
         if (!somexyspace(croom, mp, 2)) {
             if (!somexyspace(croom, mp, 0)
-                && !In_hell(&u.uz)
-                && !Is_nymph(&u.uz)
-                && !Is_forest(&u.uz))
+                && !In_hell(&u.uz))
                 impossible("Can't place branch!");
         }
     }
@@ -2227,6 +2225,8 @@ xchar x, y;
         return;
 
     if (!(u.uz.dnum == oracle_level.dnum      /* in main dungeon */
+          && u.uz.dnum == nymph_level.dnum    /* Aphrodite's garden */
+          && u.uz.dnum == forest_level.dnum   /* Desolate Forest */
           && !at_dgn_entrance("The Quest")    /* but not Quest's entry */
           && (u_depth = depth(&u.uz)) > 10    /* beneath 10 */
           && u_depth < depth(&medusa_level))) /* and above Medusa */

src/mkmaze.c

@@ -365,8 +365,7 @@ d_level *lev;
         u_on_newpos(x, y);
         break;
     case LR_PORTAL:
-        if (!(rtype == GARDEN || rtype == FOREST))
-            mkportal(x, y, lev->dnum, lev->dlevel);
+        mkportal(x, y, lev->dnum, lev->dlevel);
         break;
     case LR_DOWNSTAIR:
     case LR_UPSTAIR:

src/mkroom.c

@@ -688,6 +688,9 @@ struct mkroom *croom; /* NULL == choose random room */
             continue;
 
         sroom->rtype = GARDEN;
+        maderoom = TRUE;
+        level.flags.has_garden = 1;
+
         /* create grass */
         for (pos.x = sroom->lx; pos.x <= sroom->hx; pos.x++) {
             for (pos.y = sroom->ly; pos.y <= sroom->hy; pos.y++) {
@@ -696,8 +699,6 @@ struct mkroom *croom; /* NULL == choose random room */
                     levl[pos.x][pos.y].typ = GRASS;
             }
         }
-        maderoom = TRUE;
-        level.flags.has_garden = 1;
 
         /* create trees/fountains */
         tried = 0;
@@ -769,6 +770,9 @@ struct mkroom *croom; /* NULL == choose random room */
             continue;
 
         sroom->rtype = FOREST;
+        maderoom = TRUE;
+        level.flags.has_forest = 1;
+
         /* create grass */
         for (pos.x = sroom->lx; pos.x <= sroom->hx; pos.x++) {
             for (pos.y = sroom->ly; pos.y <= sroom->hy; pos.y++) {
@@ -777,8 +781,6 @@ struct mkroom *croom; /* NULL == choose random room */
                     levl[pos.x][pos.y].typ = GRASS;
             }
         }
-        maderoom = TRUE;
-        level.flags.has_forest = 1;
 
         /* create dead trees and shallow water */
         tried = 0;
@@ -1068,26 +1070,41 @@ int xy_flags;
 {
     int tryct = 0;
     boolean isok;
+
     do {
         isok = TRUE;
         if (croom && !somexy(croom, pos))
             isok = FALSE;
         if ((xy_flags & 16))
             mazexy(pos);
-        if ((xy_flags & 1) && (IS_POOL(levl[pos->x][pos->y].typ)
-            || IS_FURNITURE(levl[pos->x][pos->y].typ)))
+        if ((xy_flags & 1)
+            && (IS_POOL(levl[pos->x][pos->y].typ)
+                || IS_FURNITURE(levl[pos->x][pos->y].typ)))
             isok = FALSE;
-        if (((xy_flags & 2) && (levl[pos->x][pos->y].typ != CORR))
-            || (levl[pos->x][pos->y].typ != ROOM))
+        if ((xy_flags & 2)
+            && ((levl[pos->x][pos->y].typ != CORR)
+                || (levl[pos->x][pos->y].typ != ROOM)
+                || (levl[pos->x][pos->y].typ != SAND)
+                || (levl[pos->x][pos->y].typ != GRASS)))
             isok = FALSE;
         if ((xy_flags & 4) && (sobj_at(BOULDER, pos->x, pos->y)))
             isok = FALSE;
         if ((xy_flags & 8) && bydoor(pos->x, pos->y))
             isok = FALSE;
     } while ((!isok || !SPACE_POS(levl[pos->x][pos->y].typ)
-             || occupied(pos->x, pos->y)) && (++tryct < 500));
-    if ((tryct < 500) && isok)
+              || !(levl[pos->x][pos->y].typ == ROOM
+                   || levl[pos->x][pos->y].typ == CORR
+                   || levl[pos->x][pos->y].typ == ICE
+                   || levl[pos->x][pos->y].typ == SAND
+                   || levl[pos->x][pos->y].typ == GRASS)
+              || occupied(pos->x, pos->y))
+             && (++tryct < 2000));
+
+    /* make tryct greater than the total number of possible
+       tile spaces on any given map */
+    if ((tryct < 2000) && isok)
         return TRUE;
+
     return FALSE;
 }