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AI retreat_injured CA: improve retreat threshold calculation

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The main problem was that the previous calculation was based on the 'caution' aspect. While that is not technically wrong, caution is also used for other purposes and there are mainline (and presumably UMC) scenarios that use large values for caution. In those cases, units retreated that were barely injured. This, again, might even be desirable for some use cases, but it needs to be decoupled from the other uses of caution. Thus, the new 'retreat_factor' aspect is used now.

In addition, the calculation is now based on a unit's maximum hitpoints, rather than its level.
This commit is contained in:
mattsc 2021-02-26 06:49:37 -08:00
parent efe5a4d497
commit 903e03d68a
2 changed files with 25 additions and 20 deletions
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2
data/ai/lua/ca_retreat_injured.lua
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@ -12,7 +12,7 @@ function ca_retreat_injured:evaluation(cfg, data, filter_own)
local start_time, ca_name = wesnoth.get_time_stamp() / 1000., 'retreat_injured'
if AH.print_eval() then AH.print_ts(' - Evaluating retreat_injured CA:') end
if (ai.aspects.caution <= 0) then
if (ai.aspects.retreat_factor <= 0) then
if AH.print_eval() then AH.done_eval_messages(start_time, ca_name) end
return 0
end

43
data/ai/lua/retreat.lua
View file

@ -7,40 +7,45 @@ local AH = wesnoth.require "ai/lua/ai_helper.lua"
local BC = wesnoth.require "ai/lua/battle_calcs.lua"
local LS = wesnoth.require "location_set"
local function print_dbg(...)
local show_debug_info = false -- manually set to true/false depending on whether output is desired
if wesnoth.game_config.debug and show_debug_info then
std_print('Retreat debug: ', ...)
end
end
local retreat_functions = {}
function retreat_functions.min_hp(unit)
-- The minimum hp to retreat is a function of level and terrain defense
-- We want to stay longer on good terrain and leave early on very bad terrain
-- The minimum hp to retreat is a function of hitpoints and terrain defense
-- We want to stay longer on good terrain and leave early on bad terrain
-- It can be influenced by the 'retreat_factor' AI aspect
-- Take caution into account here. We want the multiplier to be:
-- 1 for default caution (0.25)
-- 0 for minimal caution <= 0
-- 2 for caution = 1
local caution_factor = ai.aspects.caution
if (caution_factor < 0) then caution_factor = 0 end
caution_factor = math.sqrt(caution_factor) * 2
local retreat_factor = ai.aspects.retreat_factor
local hp_per_level = (100 - unit:defense_on(wesnoth.get_terrain(unit.x, unit.y)))/15 * caution_factor
local level = unit.level
-- Leaders are more valuable and should retreat earlier
if unit.canrecruit then retreat_factor = retreat_factor * 1.5 end
-- Leaders are considered to be higher level because of their value
if unit.canrecruit then level = level+2 end
-- Higher retreat willingness on bad terrain
local retreat_factor = retreat_factor * (100 - unit:defense_on(wesnoth.get_terrain(unit.x, unit.y))) / 50
local min_hp = hp_per_level*(level+2)
local min_hp = retreat_factor * unit.max_hitpoints
-- Account for poison damage on next turn
if unit.status.poisoned then min_hp = min_hp + wesnoth.game_config.poison_amount end
-- Make sure that units are actually injured (only relevant for low-HP units)
-- Want this to be roughly half the units HP at caution=0, close to full HP at caution=1
local hp_factor = 0.5 + 0.25 * caution_factor
if (hp_factor > 1) then hp_factor = 1 end
local max_min_hp = (unit.max_hitpoints - 4) * hp_factor
-- Large values of retreat_factor could cause fully healthy units to retreat.
-- We require a unit to be down more than 10 HP, or half its HP for units with less than 20 max_HP.
local max_hp = unit.max_hitpoints
local max_min_hp = math.max(max_hp - 10, max_hp / 2)
if (min_hp > max_min_hp) then
min_hp = max_min_hp
end
local retreat_str = ''
if (unit.hitpoints < min_hp) then retreat_str = ' --> retreat' end
print_dbg(string.format('%20s %3d/%-3d HP threshold: %5.1f HP%s', unit.id, unit.hitpoints, unit.max_hitpoints, min_hp, retreat_str))
return min_hp
end