Added a new hook: HOOK_CANUSEWEAPON

Updated NPC armor appearance mod script.

artifacts/mods/gl_npcarmor.ssl

@@ -9,7 +9,7 @@
    NOTE: this script requires compiler from sfall modderspack with -s option
    (short circuit evaluation)
 
-   version 1.1
+   version 1.2
 
 */
 
@@ -21,6 +21,7 @@
 #define FID_OBJ_CRITTER  (0x01000000)
 
 procedure update_armor_apperance;
+procedure canuseweapon_handler;
 
 variable
    modIni := "npcarmor.ini",
@@ -203,6 +204,7 @@ procedure start begin
       register_hook_proc(HOOK_INVENWIELD, invenwield_handler);
       register_hook_proc(HOOK_ADJUSTFID, adjustfid_handler);
       register_hook_proc(HOOK_INVENTORYMOVE, inventorymove_handler);
+      register_hook_proc_spec(HOOK_CANUSEWEAPON, canuseweapon_handler);
 
       debug_msg("NPC armor appearance mod: Done.");
    end
@@ -220,3 +222,14 @@ procedure update_armor_apperance begin
       end
    end
 end
+
+procedure canuseweapon_handler begin
+   variable critter, canWield;
+   critter := get_sfall_arg;
+   if (critter) then begin
+      canWield := check_weapon_change(critter, get_sfall_arg, true);
+      //if (canWield != 0) then canWield := 1;
+      set_sfall_arg(3, canWield); // override result
+      set_sfall_return(canWield);
+   end
+end

artifacts/scripting/headers/sfall.h

@@ -73,6 +73,7 @@
 #define HOOK_ADJUSTRADS       (45)
 #define HOOK_ROLLCHECK        (46)
 #define HOOK_BESTWEAPON       (47)
+#define HOOK_CANUSEWEAPON     (48)
 
 //Valid arguments to list_begin
 #define LIST_CRITTERS    (0)

artifacts/scripting/hookscripts.md

@@ -888,3 +888,19 @@ Critter arg4 - the target of the critter (can be 0)
 
 Item    ret0 - overrides the chosen best weapon
 ```
+
+-------------------------------------------
+
+#### `HOOK_CANUSEWEAPON (hs_canuseweapon.int)`
+
+Run when the AI checks whether it can use a weapon.
+This mostly happens when NPCs try to find weapons in their inventory or on the map.
+
+```
+Critter arg0 - the critter doing the check
+Item    arg1 - the weapon being checked
+int     arg2 - attack type (see ATKTYPE_* constants)
+int     arg3 - original result of engine function: 1 - can use, 0 - can't use
+
+int     ret0 - overrides the result of engine function. Any non-zero value allows using the weapon
+```

sfall/FalloutEngine/Functions_def.h

@@ -19,6 +19,8 @@
 	because the compiler builds the better/optimized code when calling the engine functions
 */
 WRAP_WATCOM_FFUNC4(long, _word_wrap, const char*, text, int, maxWidth, DWORD*, buf, BYTE*, count)
+WRAP_WATCOM_FFUNC4(fo::GameObject*, ai_best_weapon, fo::GameObject*, source, fo::GameObject*, prevItem, fo::GameObject*, checkItem, fo::GameObject*, target)
+WRAP_WATCOM_FFUNC3(bool, ai_can_use_weapon, fo::GameObject*, critter, fo::GameObject*, item, DWORD, hitMode)
 WRAP_WATCOM_FFUNC3(long, ai_have_ammo, fo::GameObject*, critter, fo::GameObject*, item, fo::GameObject**, outAmmo)
 WRAP_WATCOM_FFUNC3(long, ai_pick_hit_mode, fo::GameObject*, source, fo::GameObject*, item, fo::GameObject*, target)
 WRAP_WATCOM_FFUNC3(fo::GameObject*, ai_search_inven_weap, fo::GameObject*, source, long, apCheck, fo::GameObject*, target)

sfall/Game/combatAI.cpp

@@ -0,0 +1,28 @@
+/*
+ *    sfall
+ *    Copyright (C) 2008-2021  The sfall team
+ *
+ */
+
+//#include "..\main.h"
+#include "..\FalloutEngine\Fallout2.h"
+
+#include "..\Modules\HookScripts\CombatHs.h"
+
+#include "combatAI.h"
+
+namespace game
+{
+
+namespace sf = sfall;
+
+// Implementation of ai_can_use_weapon_ engine function with the HOOK_CANUSEWEAPON hook
+long CombatAI::ai_can_use_weapon(fo::GameObject* source, fo::GameObject* weapon, long hitMode) {
+	long result = fo::func::ai_can_use_weapon(source, weapon, hitMode);
+	return sf::CanUseWeaponHook_Invoke(result, source, weapon, hitMode);
+}
+
+void CombatAI::init() { // TODO: add to main.cpp
+}
+
+}

sfall/Game/combatAI.h

@@ -0,0 +1,19 @@
+/*
+ *    sfall
+ *    Copyright (C) 2008-2021  The sfall team
+ *
+ */
+
+#pragma once
+
+namespace game
+{
+
+class CombatAI {
+public:
+	static void init();
+
+	static long ai_can_use_weapon(fo::GameObject* source, fo::GameObject* weapon, long hitMode);
+};
+
+}

sfall/Modules/HookScripts.cpp

@@ -109,6 +109,7 @@ static HooksInjectInfo injectHooks[] = {
 	{HOOK_ADJUSTRADS,       Inject_AdjustRadsHook,       1},  // always embedded for party control fix
 	{HOOK_ROLLCHECK,        Inject_RollCheckHook,        0},
 	{HOOK_BESTWEAPON,       Inject_BestWeaponHook,       0},
+	{HOOK_CANUSEWEAPON,     Inject_CanUseWeaponHook,     0},
 };
 
 void HookScripts::InjectingHook(int hookId) {

sfall/Modules/HookScripts.h

@@ -74,6 +74,7 @@ enum HookType
 	HOOK_ADJUSTRADS       = 45,
 	HOOK_ROLLCHECK        = 46,
 	HOOK_BESTWEAPON       = 47,
+	HOOK_CANUSEWEAPON     = 48,
 	HOOK_COUNT
 };
 

sfall/Modules/HookScripts/CombatHs.cpp

@@ -600,12 +600,12 @@ static fo::GameObject* __stdcall BestWeaponHook_Script(fo::GameObject* bestWeapo
 
 static void __declspec(naked) ai_search_inven_weap_hook() {
 	__asm {
-		push ecx;
-		push ebx;
-		push edx;
-		push eax;
+		push ecx; // target
+		push ebx; // weapon2 (secondary)
+		push edx; // weapon1 (primary)
+		push eax; // source
 		call fo::funcoffs::ai_best_weapon_;
-		push eax;
+		push eax; // bestWeapon
 		call BestWeaponHook_Script;
 		retn;
 	}
@@ -619,6 +619,48 @@ fo::GameObject* BestWeaponHook_Invoke(fo::GameObject* bestWeapon, fo::GameObject
 }
 */
 
+static long __stdcall CanUseWeaponHook_Script(long result, fo::GameObject* source, fo::GameObject* weapon, long hitMode) {
+	BeginHook();
+	argCount = 4;
+
+	args[0] = (DWORD)source;
+	args[1] = (DWORD)weapon;
+	args[2] = hitMode;
+	args[3] = result;
+
+	RunHookScript(HOOK_CANUSEWEAPON);
+
+	if (cRet > 0) {
+		result = rets[0];
+		if (result != 0) result = 1;
+	}
+
+	EndHook();
+	return result;
+}
+
+static void __declspec(naked) CanUseWeaponHook() {
+	__asm {
+		push ecx;
+		push ebx; // hitMode
+		push edx; // weapon
+		push eax; // source
+		call fo::funcoffs::ai_can_use_weapon_;
+		push eax; // result
+		call CanUseWeaponHook_Script;
+		pop  ecx;
+		retn;
+	}
+}
+
+long CanUseWeaponHook_Invoke(long result, fo::GameObject* source, fo::GameObject* weapon, long hitMode) {
+	return (HookScripts::HookHasScript(HOOK_CANUSEWEAPON))
+	       ? CanUseWeaponHook_Script(result, source, weapon, hitMode)
+	       : result;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
 void Inject_ToHitHook() {
 	HookCalls(ToHitHook, {
 		0x421686, // combat_safety_invalidate_weapon_func_
@@ -709,6 +751,14 @@ void Inject_BestWeaponHook() {
 	HookCall(0x429A59, ai_search_inven_weap_hook);
 }
 
+void Inject_CanUseWeaponHook() {
+	HookCalls(CanUseWeaponHook, {
+		0x429A1B, // ai_search_inven_weap_
+		0x429CF2, // ai_search_environ_
+		0x429E1C  // ai_pick_hit_mode_
+	});
+}
+
 void InitCombatHookScripts() {
 	HookScripts::LoadHookScript("hs_tohit", HOOK_TOHIT);
 	HookScripts::LoadHookScript("hs_afterhitroll", HOOK_AFTERHITROLL);
@@ -722,6 +772,7 @@ void InitCombatHookScripts() {
 	HookScripts::LoadHookScript("hs_subcombatdmg", HOOK_SUBCOMBATDAMAGE);
 	HookScripts::LoadHookScript("hs_targetobject", HOOK_TARGETOBJECT);
 	HookScripts::LoadHookScript("hs_bestweapon", HOOK_BESTWEAPON);
+	HookScripts::LoadHookScript("hs_canuseweapon", HOOK_CANUSEWEAPON);
 }
 
 }

sfall/Modules/HookScripts/CombatHs.h

@@ -19,11 +19,13 @@ void Inject_OnExplosionHook();
 void Inject_SubCombatDamageHook();
 void Inject_TargetObjectHook();
 void Inject_BestWeaponHook();
+void Inject_CanUseWeaponHook();
 
 int __fastcall AmmoCostHook_Script(DWORD hookType, fo::GameObject* weapon, DWORD &rounds);
 
 long CalcApCostHook_Invoke(fo::GameObject* source, long hitMode, long isCalled, long cost, fo::GameObject* weapon);
 //void FindTargetHook_Invoke(fo::GameObject* targets[], fo::GameObject* attacker);
 //fo::GameObject* BestWeaponHook_Invoke(fo::GameObject* bestWeapon, fo::GameObject* source, fo::GameObject* weapon1, fo::GameObject* weapon2, fo::GameObject* target);
+long CanUseWeaponHook_Invoke(long result, fo::GameObject* source, fo::GameObject* weapon, long hitMode);
 
 }

sfall/ddraw.vcxproj

@@ -291,6 +291,7 @@
     <ClInclude Include="FalloutEngine\Variables.h" />
     <ClInclude Include="FalloutEngine\Functions.h" />
     <ClInclude Include="FalloutEngine\Functions_def.h" />
+    <ClInclude Include="Game\combatAI.h" />
     <ClInclude Include="Game\inventory.h" />
     <ClInclude Include="Game\items.h" />
     <ClInclude Include="Game\objects.h" />
@@ -402,6 +403,7 @@
     <ClCompile Include="FalloutEngine\FunctionOffsets.cpp" />
     <ClCompile Include="FalloutEngine\Variables.cpp" />
     <ClCompile Include="FalloutEngine\Functions.cpp" />
+    <ClCompile Include="Game\combatAI.cpp" />
     <ClCompile Include="Game\inventory.cpp" />
     <ClCompile Include="Game\items.cpp" />
     <ClCompile Include="Game\objects.cpp" />

sfall/ddraw.vcxproj.filters

@@ -343,6 +343,9 @@
       <Filter>Game</Filter>
     </ClInclude>
     <ClInclude Include="Translate.h" />
+    <ClInclude Include="Game\combatAI.h">
+      <Filter>Game</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="main.cpp" />
@@ -636,6 +639,9 @@
       <Filter>Game</Filter>
     </ClCompile>
     <ClCompile Include="Translate.cpp" />
+    <ClCompile Include="Game\combatAI.cpp">
+      <Filter>Game</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ResourceCompile Include="version.rc" />