From bb3513956c010803bbbd46c7d354f4b85c957e34 Mon Sep 17 00:00:00 2001
From: Alexander Batalov <alex.batalov@gmail.com>
Date: Sat, 2 Sep 2023 21:34:41 +0300
Subject: [PATCH] Add op_force_encounter

---
 src/sfall_opcodes.cc | 17 +++++++++++++++
 src/worldmap.cc      | 52 ++++++++++++++++++++++++++++++++++++++++++++
 src/worldmap.h       |  7 ++++++
 3 files changed, 76 insertions(+)

diff --git a/src/sfall_opcodes.cc b/src/sfall_opcodes.cc
index ea45d4e..8d8cd57 100644
--- a/src/sfall_opcodes.cc
+++ b/src/sfall_opcodes.cc
@@ -138,6 +138,13 @@ static void op_in_world_map(Program* program)
     programStackPushInteger(program, GameMode::isInGameMode(GameMode::kWorldmap) ? 1 : 0);
 }
 
+// force_encounter
+static void op_force_encounter(Program* program)
+{
+    int map = programStackPopInteger(program);
+    wmForceEncounter(map, 0);
+}
+
 // set_world_map_pos
 static void op_set_world_map_pos(Program* program)
 {
@@ -541,6 +548,14 @@ static void op_get_attack_type(Program* program)
     }
 }
 
+// force_encounter_with_flags
+static void op_force_encounter_with_flags(Program* program)
+{
+    unsigned int flags = programStackPopInteger(program);
+    int map = programStackPopInteger(program);
+    wmForceEncounter(map, flags);
+}
+
 // atoi
 static void opParseInt(Program* program)
 {
@@ -894,6 +909,7 @@ void sfallOpcodesInit()
     interpreterRegisterOpcode(0x816A, op_set_global_script_repeat);
     interpreterRegisterOpcode(0x816C, op_key_pressed);
     interpreterRegisterOpcode(0x8170, op_in_world_map);
+    interpreterRegisterOpcode(0x8171, op_force_encounter);
     interpreterRegisterOpcode(0x8172, op_set_world_map_pos);
     interpreterRegisterOpcode(0x8193, opGetCurrentHand);
     interpreterRegisterOpcode(0x819B, op_set_global_script_type);
@@ -927,6 +943,7 @@ void sfallOpcodesInit()
     interpreterRegisterOpcode(0x8221, opGetScreenHeight);
     interpreterRegisterOpcode(0x8224, op_create_message_window);
     interpreterRegisterOpcode(0x8228, op_get_attack_type);
+    interpreterRegisterOpcode(0x8229, op_force_encounter_with_flags);
     interpreterRegisterOpcode(0x822D, opCreateArray);
     interpreterRegisterOpcode(0x822E, opSetArray);
     interpreterRegisterOpcode(0x822F, opGetArray);
diff --git a/src/worldmap.cc b/src/worldmap.cc
index 3243d8d..8b30255 100644
--- a/src/worldmap.cc
+++ b/src/worldmap.cc
@@ -817,6 +817,8 @@ static double gGameTimeIncRemainder = 0.0;
 static FrmImage _backgroundFrmImage;
 static FrmImage _townFrmImage;
 static bool wmFaded = false;
+static int wmForceEncounterMapId = -1;
+static unsigned int wmForceEncounterFlags = 0;
 
 static inline bool cityIsValid(int city)
 {
@@ -929,6 +931,9 @@ static int wmGenDataInit()
     wmGenData.tabsScrollingDelta = 0;
     wmGenData.viewportMaxX = 0;
 
+    wmForceEncounterMapId = -1;
+    wmForceEncounterFlags = 0;
+
     return 0;
 }
 
@@ -979,6 +984,9 @@ static int wmGenDataReset()
 
     wmMarkSubTileRadiusVisited(wmGenData.worldPosX, wmGenData.worldPosY);
 
+    wmForceEncounterMapId = -1;
+    wmForceEncounterFlags = 0;
+
     return 0;
 }
 
@@ -3347,6 +3355,33 @@ static int wmRndEncounterOccurred()
         }
     }
 
+    // SFALL: Handle forced encounter.
+    // CE: In Sfall a check for forced encounter is inserted instead of check
+    // for Horrigan encounter (above). This implemenation gives Horrigan
+    // encounter a priority.
+    if (wmForceEncounterMapId != -1) {
+        if ((wmForceEncounterFlags & ENCOUNTER_FLAG_NO_CAR) != 0) {
+            if (wmGenData.isInCar) {
+                wmMatchAreaContainingMapIdx(wmForceEncounterMapId, &(wmGenData.currentCarAreaId));
+            }
+        }
+
+        // For unknown reason fadeout and blinking icon are mutually exclusive.
+        if ((wmForceEncounterFlags & ENCOUNTER_FLAG_FADEOUT) != 0) {
+            wmFadeOut();
+        } else if ((wmForceEncounterFlags & ENCOUNTER_FLAG_NO_ICON) == 0) {
+            bool special = (wmForceEncounterFlags & ENCOUNTER_FLAG_ICON_SP) != 0;
+            wmBlinkRndEncounterIcon(special);
+        }
+
+        mapLoadById(wmForceEncounterMapId);
+
+        wmForceEncounterMapId = -1;
+        wmForceEncounterFlags = 0;
+
+        return 1;
+    }
+
     // NOTE: Uninline.
     wmPartyFindCurSubTile();
 
@@ -6608,4 +6643,21 @@ void wmCarSetCurrentArea(int area)
     wmGenData.currentCarAreaId = area;
 }
 
+void wmForceEncounter(int map, unsigned int flags)
+{
+    if ((wmForceEncounterFlags & (1 << 31)) != 0) {
+        return;
+    }
+
+    wmForceEncounterMapId = map;
+    wmForceEncounterFlags = flags;
+
+    // I don't quite understand the reason why locking needs one more flag.
+    if ((wmForceEncounterFlags & ENCOUNTER_FLAG_LOCK) != 0) {
+        wmForceEncounterFlags |= (1 << 31);
+    } else {
+        wmForceEncounterFlags &= ~(1 << 31);
+    }
+}
+
 } // namespace fallout
diff --git a/src/worldmap.h b/src/worldmap.h
index 901b0a6..20ea1c2 100644
--- a/src/worldmap.h
+++ b/src/worldmap.h
@@ -229,6 +229,12 @@ typedef enum Map {
     MAP_IN_GAME_MOVIE1 = 149,
 } Map;
 
+#define ENCOUNTER_FLAG_NO_CAR 0x1
+#define ENCOUNTER_FLAG_LOCK 0x2
+#define ENCOUNTER_FLAG_NO_ICON 0x4
+#define ENCOUNTER_FLAG_ICON_SP 0x8
+#define ENCOUNTER_FLAG_FADEOUT 0x10
+
 extern unsigned char* circleBlendTable;
 
 int wmWorldMap_init();
@@ -279,6 +285,7 @@ int wmTeleportToArea(int areaIdx);
 
 void wmSetPartyWorldPos(int x, int y);
 void wmCarSetCurrentArea(int area);
+void wmForceEncounter(int map, unsigned int flags);
 
 } // namespace fallout