Implement a slightly more sensible aiming AI in siege engine.

plugins/devel/siege-engine.cpp

@@ -112,7 +112,7 @@ static bool is_in_range(const coord_range &target, df::coord pos)
 static std::pair<int, int> get_engine_range(df::building_siegeenginest *bld)
 {
     if (bld->type == siegeengine_type::Ballista)
-        return std::make_pair(0, 200);
+        return std::make_pair(1, 200);
     else
         return std::make_pair(30, 100);
 }
@@ -291,7 +291,7 @@ static EngineInfo *find_engine(df::building *bld, bool create = false)
     );
     obj->is_catapult = (ebld->type == siegeengine_type::Catapult);
     obj->proj_speed = 2;
-    obj->hit_delay = 3;
+    obj->hit_delay = obj->is_catapult ? 2 : -1;
     obj->fire_range = get_engine_range(ebld);
 
     obj->ammo_vector_id = job_item_vector_id::BOULDER;
@@ -1107,6 +1107,9 @@ struct UnitPath {
             float time = unit->counters.job_counter+0.5f;
             float speed = Units::computeMovementSpeed(unit)/100.0f;
 
+            if (unit->counters.unconscious > 0)
+                time += unit->counters.unconscious;
+
             for (size_t i = 0; i < upath.size(); i++)
             {
                 df::coord new_pos = upath[i];
@@ -1282,6 +1285,74 @@ static int proposeUnitHits(lua_State *L)
     return 1;
 }
 
+static int computeNearbyWeight(lua_State *L)
+{
+    auto engine = find_engine(L, 1);
+    luaL_checktype(L, 2, LUA_TTABLE);
+    luaL_checktype(L, 3, LUA_TTABLE);
+    const char *fname = luaL_optstring(L, 4, "nearby_weight");
+
+    std::vector<UnitPath*> units;
+    std::vector<float> weights;
+
+    lua_pushnil(L);
+
+    while (lua_next(L, 3))
+    {
+        df::unit *unit;
+        if (lua_isnumber(L, -2))
+            unit = df::unit::find(lua_tointeger(L, -2));
+        else
+            unit = Lua::CheckDFObject<df::unit>(L, -2);
+        if (!unit)
+            continue;
+        units.push_back(UnitPath::get(unit));
+        weights.push_back(lua_tonumber(L, -1));
+        lua_pop(L, 1);
+    }
+
+    lua_pushnil(L);
+
+    while (lua_next(L, 2))
+    {
+        Lua::StackUnwinder frame(L, 1);
+
+        lua_getfield(L, frame[1], "unit");
+        df::unit *unit = Lua::CheckDFObject<df::unit>(L, -1);
+
+        lua_getfield(L, frame[1], "time");
+        float time = luaL_checknumber(L, lua_gettop(L));
+
+        df::coord pos;
+
+        lua_getfield(L, frame[1], "pos");
+        if (lua_isnil(L, -1))
+        {
+            if (!unit) luaL_error(L, "either unit or pos is required");
+            pos = UnitPath::get(unit)->posAtTime(time);
+        }
+        else
+            Lua::CheckDFAssign(L, &pos, -1);
+
+        float sum = 0.0f;
+
+        for (size_t i = 0; i < units.size(); i++)
+        {
+            if (units[i]->unit == unit)
+                continue;
+
+            auto diff = units[i]->posAtTime(time) - pos;
+            float dist = 1 + sqrtf(diff.x*diff.x + diff.y*diff.y + diff.z*diff.z);
+            sum += weights[i]/(dist*dist);
+        }
+
+        lua_pushnumber(L, sum);
+        lua_setfield(L, frame[1], fname);
+    }
+
+    return 0;
+}
+
 /*
  * Projectile hook
  */
@@ -1698,6 +1769,7 @@ DFHACK_PLUGIN_LUA_COMMANDS {
     DFHACK_LUA_COMMAND(traceUnitPath),
     DFHACK_LUA_COMMAND(unitPosAtTime),
     DFHACK_LUA_COMMAND(proposeUnitHits),
+    DFHACK_LUA_COMMAND(computeNearbyWeight),
     DFHACK_LUA_END
 };
 

plugins/lua/siege-engine.lua

@@ -8,37 +8,221 @@ local _ENV = mkmodule('plugins.siege-engine')
  * clearTargetArea(building)
  * setTargetArea(building, point1, point2) -> true/false
 
---]]
+ * isLinkedToPile(building,pile) -> true/false
+ * getStockpileLinks(building) -> {pile}
+ * addStockpileLink(building,pile) -> true/false
+ * removeStockpileLink(building,pile) -> true/false
+
+ * saveWorkshopProfile(building) -> profile
+
+ * getAmmoItem(building) -> item_type
+ * setAmmoItem(building,item_type) -> true/false
+
+ * isPassableTile(pos) -> true/false
+ * isTreeTile(pos) -> true/false
+ * isTargetableTile(pos) -> true/false
+
+ * getTileStatus(building,pos) -> 'invalid/ok/out_of_range/blocked/semiblocked'
+ * paintAimScreen(building,view_pos_xyz,left_top_xy,size_xy)
+
+ * canTargetUnit(unit) -> true/false
+
+ proj_info = { target = pos, [delta = float/pos], [factor = int] }
+
+ * projPosAtStep(building,proj_info,step) -> pos
+ * projPathMetrics(building,proj_info) -> {
+       hit_type = 'wall/floor/ceiling/map_edge/tree',
+       collision_step = int,
+       collision_z_step = int,
+       goal_distance = int,
+       goal_step = int/nil,
+       goal_z_step = int/nil,
+       status = 'ok/out_of_range/blocked'
+   }
+
+ * adjustToTarget(building,pos) -> pos,ok=true/false
+
+ * traceUnitPath(unit) -> { {x=int,y=int,z=int[,from=time][,to=time]} }
+ * unitPosAtTime(unit, time) -> pos
+
+ * proposeUnitHits(building) -> { {
+       pos=pos, unit=unit, time=float, dist=int,
+       [lmargin=float,] [rmargin=float,]
+   } }
+
+ * computeNearbyWeight(building,hits,{[id/unit]=score}[,fname])
+
+]]
 
 Z_STEP_COUNT = 15
 Z_STEP = 1/31
 
+function getMetrics(engine, path)
+    path.metrics = path.metrics or projPathMetrics(engine, path)
+    return path.metrics
+end
+
 function findShotHeight(engine, target)
     local path = { target = target, delta = 0.0 }
 
-    if projPathMetrics(engine, path).goal_step then
+    if getMetrics(engine, path).goal_step then
         return path
     end
 
-    for i = 1,Z_STEP_COUNT do
-        path.delta = i*Z_STEP
-        if projPathMetrics(engine, path).goal_step then
+    local tpath = { target = target, delta = Z_STEP_COUNT*Z_STEP }
+
+    if getMetrics(engine, tpath).goal_step then
+        for i = 1,Z_STEP_COUNT-1 do
+            path = { target = target, delta = i*Z_STEP }
+            if getMetrics(engine, path).goal_step then
                 return path
             end
+        end
 
-        path.delta = -i*Z_STEP
-        if projPathMetrics(engine, path).goal_step then
+        return tpath
+    end
+
+    tpath = { target = target, delta = -Z_STEP_COUNT*Z_STEP }
+
+    if getMetrics(engine, tpath).goal_step then
+        for i = 1,Z_STEP_COUNT-1 do
+            path = { target = target, delta = -i*Z_STEP }
+            if getMetrics(engine, path).goal_step then
                 return path
             end
         end
+
+        return tpath
+    end
+end
+
+function findReachableTargets(engine, targets)
+    local reachable = {}
+    for _,tgt in ipairs(targets) do
+        tgt.path = findShotHeight(engine, tgt.pos)
+        if tgt.path then
+            table.insert(reachable, tgt)
+        end
+    end
+    return reachable
+end
+
+recent_targets = recent_targets or {}
+
+if dfhack.is_core_context then
+    dfhack.onStateChange[_ENV] = function(code)
+        if code == SC_MAP_LOADED then
+            recent_targets = {}
+        end
+    end
+end
+
+function saveRecent(unit)
+    local id = unit.id
+    local tgt = recent_targets
+    tgt[id] = (tgt[id] or 0) + 1
+    dfhack.timeout(3, 'days', function()
+        tgt[id] = math.max(0, tgt[id]-1)
+    end)
+end
+
+function getBaseUnitWeight(unit)
+    if dfhack.units.isCitizen(unit) then
+        return -10
+    elseif unit.flags1.diplomat or unit.flags1.merchant then
+        return -2
+    elseif unit.flags1.tame and unit.civ_id == df.global.ui.civ_id then
+        return -1
+    else
+        local rv = 1
+        if unit.flags1.marauder then rv = rv + 0.5 end
+        if unit.flags1.active_invader then rv = rv + 1 end
+        if unit.flags1.invader_origin then rv = rv + 1 end
+        if unit.flags1.invades then rv = rv + 1 end
+        if unit.flags1.hidden_ambusher then rv = rv + 1 end
+        return rv
+    end
+end
+
+function getUnitWeight(unit)
+    local base = getBaseUnitWeight(unit)
+    return base * math.pow(0.7, recent_targets[unit.id] or 0)
+end
+
+function unitWeightCache()
+    local cache = {}
+    return cache, function(unit)
+        local id = unit.id
+        cache[id] = cache[id] or getUnitWeight(unit)
+        return cache[id]
+    end
+end
+
+function scoreTargets(engine, reachable)
+    local ucache, get_weight = unitWeightCache()
+
+    for _,tgt in ipairs(reachable) do
+        tgt.score = get_weight(tgt.unit)
+        if tgt.lmargin and tgt.lmargin < 3 then
+            tgt.score = tgt.score * tgt.lmargin / 3
+        end
+        if tgt.rmargin and tgt.rmargin < 3 then
+            tgt.score = tgt.score * tgt.rmargin / 3
+        end
+    end
+
+    computeNearbyWeight(engine, reachable, ucache)
+
+    for _,tgt in ipairs(reachable) do
+        tgt.score = (tgt.score + tgt.nearby_weight*0.7) * math.pow(0.995, tgt.time/3)
+    end
+
+    table.sort(reachable, function(a,b)
+        return a.score > b.score or (a.score == b.score and a.time < b.time)
+    end)
+end
+
+function pickUniqueTargets(reachable)
+    local unique = {}
+
+    if #reachable > 0 then
+        local pos_table = {}
+        local first_score = reachable[1].score
+
+        for i,tgt in ipairs(reachable) do
+            if tgt.score < 0 or tgt.score < 0.1*first_score then
+                break
+            end
+            local x,y,z = pos2xyz(tgt.pos)
+            local key = x..':'..y..':'..z
+            if pos_table[key] then
+                table.insert(pos_table[key].units, tgt.unit)
+            else
+                table.insert(unique, tgt)
+                pos_table[key] = tgt
+                tgt.units = { tgt.unit }
+            end
+        end
+    end
+
+    return unique
 end
 
 function doAimProjectile(engine, item, target_min, target_max, skill)
     print(item, df.skill_rating[skill])
+
     local targets = proposeUnitHits(engine)
-    if #targets > 0 then
-        local rnd = math.random(#targets)
-        return findShotHeight(engine, targets[rnd].pos)
+    local reachable = findReachableTargets(engine, targets)
+    scoreTargets(engine, reachable)
+    local unique = pickUniqueTargets(reachable)
+
+    if #unique > 0 then
+        local cnt = math.max(math.min(#unique,5), math.min(10, math.floor(#unique/2)))
+        local rnd = math.random(cnt)
+        for _,u in ipairs(unique[rnd].units) do
+            saveRecent(u)
+        end
+        return unique[rnd].path
     end
 end