From 6f62cfd46667226752faec6680356b56db6d5767 Mon Sep 17 00:00:00 2001
From: Alexander Batalov <alex.batalov@gmail.com>
Date: Tue, 13 Dec 2022 16:33:19 +0300
Subject: [PATCH] Fix critters dying on exit grids

---
 src/actions.cc | 40 ++++++++++++++++++++++++++++++++--------
 src/object.cc  | 18 ++++++++++++++++++
 src/object.h   |  1 +
 3 files changed, 51 insertions(+), 8 deletions(-)

diff --git a/src/actions.cc b/src/actions.cc
index 1c4daab..416b930 100644
--- a/src/actions.cc
+++ b/src/actions.cc
@@ -120,6 +120,15 @@ int actionKnockdown(Object* obj, int* anim, int maxDistance, int rotation, int d
             distance--;
             break;
         }
+
+        // CE: Fix to prevent critters (including player) cross an exit grid as
+        // a result of knockback. Sfall has similar fix done differently and it
+        // affects the player only. This approach is better since it also
+        // prevents unreachable (=unlootable) corpses on exit grids.
+        if (isExitGridAt(tile, obj->elevation)) {
+            distance--;
+            break;
+        }
     }
 
     const char* soundEffectName = sfxBuildCharName(obj, *anim, CHARACTER_SOUND_EFFECT_KNOCKDOWN);
@@ -349,16 +358,31 @@ void _show_damage_to_object(Object* a1, int damage, int flags, Object* weapon, b
                     int randomDistance = randomBetween(2, 5);
                     int randomRotation = randomBetween(0, 5);
 
-                    while (randomDistance > 0) {
-                        int tile = tileGetTileInDirection(a1->tile, randomRotation, randomDistance);
-                        Object* v35 = NULL;
-                        _make_straight_path(a1, a1->tile, tile, NULL, &v35, 4);
-                        if (v35 == NULL) {
-                            animationRegisterRotateToTile(a1, tile);
-                            animationRegisterMoveToTileStraight(a1, tile, a1->elevation, anim, 0);
+                    // CE: Fix to prevent critters (including player) to cross
+                    // an exit grid as a result of fire dance animation. See
+                    // `actionKnockdown` for notes.
+                    int rotation = randomRotation;
+                    int distance = randomDistance;
+                    while (true) {
+                        int tile = tileGetTileInDirection(a1->tile, (rotation + randomRotation) % ROTATION_COUNT, distance);
+                        if (!isExitGridAt(tile, a1->elevation)) {
+                            Object* obstacle = NULL;
+                            _make_straight_path(a1, a1->tile, tile, NULL, &obstacle, 4);
+                            if (obstacle == NULL) {
+                                animationRegisterRotateToTile(a1, tile);
+                                animationRegisterMoveToTileStraight(a1, tile, a1->elevation, anim, 0);
+                                break;
+                            }
+                        }
+
+                        if (distance > 0) {
+                            distance--;
+                        } else if (rotation < ROTATION_COUNT) {
+                            rotation++;
+                            distance = randomDistance;
+                        } else {
                             break;
                         }
-                        randomDistance--;
                     }
                 }
 
diff --git a/src/object.cc b/src/object.cc
index 3bf12ea..29f64d4 100644
--- a/src/object.cc
+++ b/src/object.cc
@@ -5243,4 +5243,22 @@ Object* objectTypedFindById(int id, int type)
     return NULL;
 }
 
+bool isExitGridAt(int tile, int elevation)
+{
+    ObjectListNode* objectListNode = gObjectListHeadByTile[tile];
+    while (objectListNode != NULL) {
+        Object* obj = objectListNode->obj;
+        if (obj->elevation == elevation) {
+            if ((obj->flags & OBJECT_HIDDEN) == 0) {
+                if (isExitGridPid(obj->pid)) {
+                    return true;
+                }
+            }
+        }
+        objectListNode = objectListNode->next;
+    }
+
+    return false;
+}
+
 } // namespace fallout
diff --git a/src/object.h b/src/object.h
index c1005e4..c397317 100644
--- a/src/object.h
+++ b/src/object.h
@@ -100,6 +100,7 @@ int _obj_load_dude(File* stream);
 void _obj_fix_violence_settings(int* fid);
 
 Object* objectTypedFindById(int id, int type);
+bool isExitGridAt(int tile, int elevation);
 
 } // namespace fallout