Added a first very basic monster ai version

The ai is similar to the old c++ version. Only the target searching is
executed every 10 ticks only now to prevent performance issues with too
many lua calls.

7 files changed, 191 insertions, 38 deletions

diff --git a/example/abilities.xml b/example/abilities.xml
index 0cbcd23c..5b8a3806 100644
--- a/example/abilities.xml
+++ b/example/abilities.xml
@@ -12,4 +12,15 @@
             useaction="attack"
         />
     </ability-category>
+    <ability-category name="Monster attack">
+        <ability
+            id="2"
+            name="Basic Monster strike"
+            rechargeable="true"
+            needed="100"
+            rechargeattribute="21"
+            target="being"
+            useaction="attack"
+        />
+    </ability-category>
 </abilities>
diff --git a/example/attributes.xml b/example/attributes.xml
index 425dd961..fd91b066 100644
--- a/example/attributes.xml
+++ b/example/attributes.xml
@@ -179,4 +179,15 @@
         minimum="0"
         maximum="100" />
     <!-- End of core-attributes definition -->
+    <attribute id="21" name="Monster attack speed"
+        desc="Attackspeed of the monster. 0 = no attacks, 100 = one per tick, 10 = one per second"
+        modifiable="false"
+        scope="monster"
+        minimum="0"
+        maximum="100" />
+    <attribute id="22" name="XP"
+        desc="The experience of this character."
+        modifiable="false"
+        scope="character"
+        minimum="0" />
 </attributes>
diff --git a/example/monsters.xml b/example/monsters.xml
index 0a4e779e..6ae92451 100644
--- a/example/monsters.xml
+++ b/example/monsters.xml
@@ -111,6 +111,8 @@ exp<TAG>:                 Tells how much experience point a monster is giving up
             magical-defence="0"
             gender="female"
             />
+        <attribute id="21" value="10" />
+        <ability id="2" />
     </monster>
 
     <monster id="4" name="Green Slime">
diff --git a/example/scripts/callbacks.lua b/example/scripts/callbacks.lua
new file mode 100644
index 00000000..af27e1a5
--- /dev/null
+++ b/example/scripts/callbacks.lua
@@ -0,0 +1,24 @@
+--[[

+

+ Allows to assign multiple functions to some callbacks

+

+--]]

+

+local monsterclass_update_old_callback = MonsterClass.on_update

+local monsterclass_update_callbacks = {}

+

+local function on_monsterclass_update(monsterclass, entity, tick)

+    for _, func in ipairs(monsterclass_update_callbacks[monsterclass]) do

+        func(entity, tick)

+    end

+end

+

+function MonsterClass:on_update(func)

+    if not monsterclass_update_callbacks[self] then

+        monsterclass_update_old_callback(self, function(entity, tick)

+            on_monsterclass_update(self, entity, tick)

+        end)

+        monsterclass_update_callbacks[self] = {}

+    end

+    table.insert(monsterclass_update_callbacks[self], func)

+end

diff --git a/example/scripts/main.lua b/example/scripts/main.lua
index 7093f112..cb657510 100644
--- a/example/scripts/main.lua
+++ b/example/scripts/main.lua
@@ -5,6 +5,9 @@
 
 --]]
 
+-- Global functions:
+require "scripts/callbacks"
+
 -- At the moment the event handlers are split up over the following files:
 require "scripts/global_events"
 require "scripts/abilities"
@@ -12,6 +15,8 @@ require "scripts/crafting"
 require "scripts/attributes"
 
 require "scripts/items/candy"
+
+require "scripts/monster/basic_ai"
 require "scripts/monster/testmonster"
 
 require "scripts/status/jump"
diff --git a/example/scripts/monster/basic_ai.lua b/example/scripts/monster/basic_ai.lua
index 9c35f42c..385099cc 100644
--- a/example/scripts/monster/basic_ai.lua
+++ b/example/scripts/monster/basic_ai.lua
@@ -7,25 +7,40 @@
 local STROLL_TIMEOUT = 20
 local STROLL_TIMEOUT_RANDOMNESS = 10
 
--- Wrapping the monster update callback in order to do the stroll ai here
-local old_on_update = MonsterClass.on_update
-local update_functions = {}
-function MonsterClass:on_update(callback)
-    update_functions[self] = callback
-end
+local TARGET_SEARCH_DELAY = 10
 
-local stroll_timer = {}
+local mob_stati = {}
 local angerlist = {}
 
 local mob_config = require "scripts/monster/settings"
 
-local function find_target(mob, config)
+local function calculate_position_priority(x1, y1, x2, y2, anger, range)
+    if math.floor(x1 / TILESIZE) == math.floor(x2 / TILESIZE) and
+       math.floor(y1 / TILESIZE) == math.floor(y2 / TILESIZE)
+    then
+        -- Both on the same tile
+        return anger * range
+    end
+
+    local path_length = get_path_length(x1, y1, x2, y2, range, "w")
+    return (range - path_length) * anger
+end
+
+local function update_attack_ai(mob, tick)
+    local config = mob_config[mob:name()]
+
     local target
     local target_priority
     local attack_x, attack_y
 
+    local mob_status = mob_stati[mob]
+    local timer = mob_status.update_target_timer
+    if timer and timer > tick then
+        return false
+    end
+
     for _, being in ipairs(get_beings_in_circle(mob, config.trackrange)) do
-        if being:type() == OBJECT_CHARACTER
+        if being:type() == TYPE_CHARACTER
            and being:action() ~= ACTION_DEAD
         then
             local anger = angerlist[being] or 0
@@ -35,63 +50,120 @@ local function find_target(mob, config)
 
             local possible_attack_positions = {
                 {
-                    x = being:x() - config.attack_distance or TILESIZE,
-                    y = being:y()
+                    x = being:x() - config.attack_distance,
+                    y = being:y(),
                 },
                 {
-
-                    x = being:x()
-                    y = being:y() - config.attack_distance or TILESIZE,
+                    x = being:x(),
+                    y = being:y() - config.attack_distance,
                 },
                 {
-
-                    x = being:x() + config.attack_distance or TILESIZE,
+                    x = being:x() + config.attack_distance,
                     y = being:y(),
                 },
                 {
-
-                    x = being:x()
-                    y = being:y() + config.attack_distance or TILESIZE,
+                    x = being:x(),
+                    y = being:y() + config.attack_distance,
                 },
             }
             for _, point in ipairs(possible_attack_positions) do
-                local priority = calculate_position_priority(mob:position(), point.x, point.y)
+                local priority = calculate_position_priority(mob:x(),
+                                                             mob:y(),
+                                                             point.x,
+                                                             point.y,
+                                                             anger,
+                                                             config.trackrange)
+
+                if priority > 0 and (not target or priority > target_priority)
+                then
+                    target = being
+                    target_priority = priority
+                    attack_x, attack_y = point.x, point.y
+                end
             end
-            
-           
-
         end
     end
-end
 
-local function stroll_update(mob, tick)
-    local stroll_tick = stroll_timer[mob]
-    local mobconfig = mob_config[mob:name()]
+    mob_status.update_target_timer = tick + TARGET_SEARCH_DELAY
 
+    if not target then
+        return false
+    end
 
-    local trackrange = mobconfig and mobconfig.trackrange or nil
+    local x, y = mob:position()
+    if x == attack_x and y == attack_y then
+        mob:use_ability(config.ability_id, target)
+    else
+        mob:walk(attack_x, attack_y)
+    end
+    return true
+end
+
+local function update_stroll_timer(mob_status, tick)
+
+    mob_status.stroll_timer = tick + STROLL_TIMEOUT
+                                   + math.random(STROLL_TIMEOUT_RANDOMNESS)
+end
 
+local function update_stroll(mob, tick)
+    local mobconfig = mob_config[mob:name()]
 
+    local mob_status = mob_stati[mob]
     local strollrange = mobconfig and mobconfig.strollrange or nil
-    if (not stroll_tick or stroll_tick <= tick) and strollrange then
+    if (not mob_status.stroll_timer or mob_status.stroll_timer <= tick) and
+        strollrange
+    then
         local x, y = mob:position()
         local destination_x = math.random(x - strollrange, x + strollrange)
         local destination_y = math.random(y - strollrange, y + strollrange)
         if is_walkable(destination_x, destination_y) then
             mob:walk(destination_x, destination_y)
         end
-        stroll_timer[mob] = tick + STROLL_TIMEOUT
-                            + math.random(STROLL_TIMEOUT_RANDOMNESS)
+        update_stroll_timer(mob_status, tick)
+    end
+end
+
+local function remove_mob(mob)
+    mob_stati[mob] = nil
+end
+
+local function update(mob, tick)
+    local mob_status = mob_stati[mob]
+    if not mob_status then
+        mob_status = {}
+        mob_stati[mob] = mob_status
+        on_remove(mob, remove_mob)
+    end
+
+    local stop_stroll = update_attack_ai(mob, tick)
+    if stop_stroll then
+        update_stroll_timer(mob_status, tick)
+    else
+        update_stroll(mob, tick)
     end
+end
 
-    local monsterclass = get_monster_class(mob:monster_id())
-    local update_function = update_functions[monsterclass]
-    if update_function then
-        return update_function(mob, tick)
+local function mob_attack(mob, target, ability_id)
+    local hp = target:base_attribute(ATTR_HP)
+    local config = mob_config[mob:name()]
+    local dealt_damage = math.min(hp, config.damage)
+    if dealt_damage > 0 then
+        local v = hp - dealt_damage
+        target:set_base_attribute(ATTR_HP, hp - dealt_damage)
+        target:add_hit_taken(dealt_damage)
     end
 end
 
--- Register all update functions for strolling
-for _, monsterclass in ipairs(get_monster_classes()) do
-    old_on_update(monsterclass, stroll_update)
+local function mob_recharged(mob, ability_id)
+    mob_stati[mob].update_target_timer = 0 -- Enforce looking for new target
+end
+
+local mob_attack_ability =
+        get_ability_info("Monster attack_Basic Monster strike")
+mob_attack_ability:on_use(mob_attack)
+mob_attack_ability:on_recharged(mob_recharged)
+
+-- Register all update functions for the ai
+for _, monsterclass in pairs(get_monster_classes()) do
+    monsterclass:on_update(update)
 end
diff --git a/example/scripts/monster/settings.lua b/example/scripts/monster/settings.lua
new file mode 100644
index 00000000..b095a2d7
--- /dev/null
+++ b/example/scripts/monster/settings.lua
@@ -0,0 +1,28 @@
+return {
+    ["Maggot"] = {
+        strollrange = TILESIZE,
+        aggressive = false,
+        trackrange = 5 * TILESIZE,
+        attack_distance = TILESIZE,
+    },
+    ["Scorpion"] = {
+        strollrange = 2 * TILESIZE,
+        aggressive = false,
+        trackrange = 5 * TILESIZE,
+        attack_distance = TILESIZE,
+    },
+    ["Red Scorpion"] = {
+        strollrange = TILESIZE,
+        aggressive = true,
+        trackrange = 5 * TILESIZE,
+        attack_distance = TILESIZE,
+        ability_id = 2,
+        damage = 1,
+    },
+    ["Green Slime"] = {
+        strollrange = TILESIZE,
+        aggressive = true,
+        trackrange = 5 * TILESIZE,
+        attack_distance = TILESIZE,
+    },
+}