sacred_k/src/game/engine/orders.h

#pragma once
// Creature orders (cEvent_creature) and the engine fields around them
// (docs/wasd.md, docs/auto-attack.md).

#include <cstddef>
#include <cstdint>

#include "game/engine/objects.h"

namespace game {

constexpr uint32_t kEventCreatureVtable = 0x0088e95c;

// cEngine fields.
constexpr size_t kEngineFlags = 0x54;  // 0x10 mouse button held (hold-to-move), 0x4000 input blocked
constexpr size_t kEngineControlledId = 0x13c;  // object id of the controlled creature

// Order commands.
constexpr uint32_t kOrderWalk = 4;
constexpr uint32_t kOrderAttack = 7;  // left click on a creature: one attack
constexpr uint32_t kOrderUseArt = 0x105;

// cEvent_creature (0x44 bytes). The meaning of +0x10..+0x20 depends on the
// command:
//   walk (4):      +0x14 2 = ground point at +0x18 / +0x1c (0: stop),
//                  +0x20 1 = re-aim while a mouse button is held
//   attack (7):    +0x18 target object id, +0x1c / +0x20 its position
//   use art (105): +0x10 target object id (0: ground / self), +0x18 / +0x1c
//                  ground point, +0x30 art id
//   hit (5):       +8 sender, +0xc / +0x10 target, +0x1c attacker id (the
//                  damage code credits it: life leech, ...; aura hits leave
//                  it 0), +0x20 four u16 damage slots (physical, ...),
//                  +0x30 float damage factor
struct CreatureOrder {
    uint32_t vtable = kEventCreatureVtable;
    uint32_t command = 0;
    uint32_t unknown08[2] = {};
    uint32_t target = 0;  // +0x10
    uint32_t groundTarget = 0;  // +0x14
    int32_t a = 0;  // +0x18
    int32_t b = 0;  // +0x1c
    int32_t c = 0;  // +0x20
    uint32_t unknown24[3] = {};
    uint32_t art = 0;  // +0x30
    uint32_t unknown34[4] = {};
};
static_assert(sizeof(CreatureOrder) == 0x44);
static_assert(offsetof(CreatureOrder, art) == 0x30);

// cEngine::SendCreatureOrder (0x6170d0): snaps ground targets, then
// creature->vf18 (cCreature::ReceiveOrder 0x52e400).
inline void SendCreatureOrder(uint8_t* engine, void* creature, CreatureOrder& order) {
    using Fn = void(__fastcall*)(void* engine, void* edx, void* creature, void* event);
    reinterpret_cast<Fn>(0x006170d0)(engine, nullptr, creature, &order);
}

inline void* ControlledCreature(uint8_t* engine) {
    return GetCreature(*reinterpret_cast<uint32_t*>(engine + kEngineControlledId));
}

// Called before cCreature::ReceiveOrder (0x52e400) handles an order (any
// creature; `caller` is the code that sent it). Register at startup.
using CreatureOrderFn = void (*)(void* creature, const CreatureOrder& order, void* caller);
void OnCreatureOrder(CreatureOrderFn callback);

// Creature fields.
constexpr size_t kCreatureId = 0xc;
constexpr size_t kCreatureX = 0x1c;
constexpr size_t kCreatureY = 0x20;
// +0x150: low word the current action, high word its phase; 0x10000 when
// standing idle. Measured on the hero: 1 walking (also up to a target),
// 3 weapon attack, 4 casting a spell (2026-10-16), 6 dying, 8 an art seen
// after walking up (2026-10-15, presumably a combat move), 5 a shot with a
// projectile weapon (bow, 2026-10-18).
constexpr size_t kCreatureAction = 0x150;
enum CreatureAction : int32_t {
    kActionIdle = 0,
    kActionWalk = 1,
    kActionAttack = 3,
    kActionCastSpell = 4,
    kActionShoot = 5,
    kActionDying = 6,
    kActionCombatMove = 8,
};
inline int32_t CurrentAction(const void* creature);

// cCreature::IsAlive (0x548ef0): not dying (+0x150 == 6), not dead (+0xfc ==
// 9), health (+0x4d8) left.
inline bool IsAlive(void* creature) {
    using Fn = char(__fastcall*)(void*, void*);
    return reinterpret_cast<Fn>(0x00548ef0)(creature, nullptr) != 0;
}

// cCreature::IsHostileTo (0x548dd0, (creature)): `other` is alive and its
// faction is hostile to this creature's (0x4226f0 / 0x423450). NPCs such as
// traders are not hostile (and not allies either).
inline bool IsHostileTo(void* creature, void* other) {
    using Fn = char(__fastcall*)(void*, void*, void*);
    return other && reinterpret_cast<Fn>(0x00548dd0)(creature, nullptr, other) != 0;
}

// cCreature::DistanceTo (0x536f20, (object id)).
inline uint32_t DistanceTo(void* creature, uint32_t id) {
    using Fn = uint32_t(__fastcall*)(void*, void*, uint32_t);
    return reinterpret_cast<Fn>(0x00536f20)(creature, nullptr, id);
}

inline int32_t CreatureField(const void* creature, size_t offset) {
    return *reinterpret_cast<const int32_t*>(static_cast<const uint8_t*>(creature) + offset);
}

inline int32_t CurrentAction(const void* creature) {
    return CreatureField(creature, kCreatureAction) & 0xffff;
}

// The distance at which two creatures touch (0x4dbaa0 on one, (the other)):
// the mean of their body radii by object type (heroes 110 with a weapon, 80
// without; monsters 70..480). A melee attacker swings from about there
// (measured: heroes started swings at 117..149).
inline int ContactDistance(void* creature, void* other) {
    using Fn = int(__fastcall*)(void*, void*, void*);
    return reinterpret_cast<Fn>(0x004dbaa0)(creature, nullptr, other);
}

// The creature's weapon class (0x546df0, (0)): from the weapons in its hands
// (+0x1d4 / +0x1d8, item type +0x1e), in the order of the motion sets:
// 0 bare hands, 1 one-handed, 2 two-handed, 3 two-handed axe, 4 staff,
// 5 dagger, 6 throwing, 7 bow, 8 two weapons, 9 / 10 blades, 11 whip,
// 12 crossbow, 13 pistol.
inline int WeaponClass(void* creature) {
    using Fn = short(__fastcall*)(void*, void*, int);
    return reinterpret_cast<Fn>(0x00546df0)(creature, nullptr, 0);
}
inline bool HasRangedWeapon(void* creature) {
    const int c = WeaponClass(creature);
    return c == 6 || c == 7 || c == 12 || c == 13;
}

// The nearest living creature hostile to `attacker` within `maxDistance` of
// `from` (a creature), other than `except` and other player heroes; one not
// in `avoid` if there is any. 0 if none.
uint32_t NearestHostile(void* attacker, void* from, double maxDistance, uint32_t except = 0,
                        const uint32_t* avoid = nullptr, size_t avoidCount = 0);

} // namespace game