[Freeciv-Dev] Re: RFC: Fixing movement code

[Raahul Kumar <raahul_da_man@xxxxxxxxx>]

--- Petr Baudis <pasky@xxxxxxxxxxx> wrote:
> > ai_military_find_victim
> > 
> > Any ideas for something better than a,b,c,d,e,f
> > 
> > f should be unit_build_cost
> 
> f is only once assigned and once used. why we shouldn't use the
> unit_type(punit)->build_cost?
> 

At first glance it seems you are correct. I wes just playing it safe with
the build cost remark. After I am sure that f is never used more than once
in other AI funcs I will make the change.

> > what the hell is b? 
> >           b = unit_type(pdef)->build_cost;
> /* bonus restored 980804 -- Syela */ - so b == bonus?
> > b = (b + 40) * punit->hp / unit_type(punit)->hp;
> and finally..
> e = ((b * a - f * d) * SHIELD_WEIGHTING / (a + d) - c * SHIELD_WEIGHTING);
> (final calculation)
> 
> i see no other usage of it. looks really like bonus enemy unit has against
> our
> one.
>

What bonus? Where does this come from? What exactly is this bonus, what effects
it etc? All I can see is that if an enemy unit is in a city this bonus applies.
Bizarre. What the hell does build-cost have to do with bonuses?
 
> c is zero everytime, no other assigment, so we can safely remove it imho.
>

Maybe, maybe not. c is used in other ai functions.
 
> d is unit_vulnerability(punit, pdef); so we can call it vuln. used in the
> final calculation only as well.
>

Yes.
 
> e is used as final coeficient used to choose best victim. so what about coef?
>

Yes. 

> a is most misterious. however, after some study of code, it seems to me it
> is kinda 'aggressivity'. in the mind comes that we can pre-compute something
> before, so it will speed things a bit.
>

Can you define aggressivity? We need some comments.You seem to understand
this code suspiciously well. Are you one of the original ai writers?
 
> so, after also some indendation etc, it would look this nice way:
> 
> static int ai_military_findvictim(struct player *pplayer, struct unit *punit,
>                                   int *dest_x, int *dest_y)
> {
>   int x, y;
>   int best = 0, belligerence;
>   struct unit *pdef;
>   struct unit *patt;
>   struct city *pcity;
> 
>   x = punit->x;
>   y = punit->y;
>   *dest_y = y;
>   *dest_x = x;
>   if (punit->unhappiness) best = 0 - 2 * MORT * TRADE_WEIGHTING; /*
> desperation */
> 
>   belligerence = unit_belligerence_primitive(punit);
> 
>   /* ferryboats do not attack.  no. -- Syela */
>   if (get_transporter_capacity(punit)) {
>     unit_list_iterate(map_get_tile(x, y)->units, aunit)
>       if (!is_sailing_unit(aunit))
>         return(0);
>     unit_list_iterate_end;
>   }
> 
>   adjc_iterate(x, y, x1, y1) {
>     pdef = get_defender(punit, x1, y1);
>     if (pdef) {
> 
>       /* horsemen in city refused to attack phalanx just outside that was
>       bodyguarding catapult - patt will resolve this bug nicely -- Syela */
>       patt = get_attacker(punit, x1, y1);
> 
>       if (can_unit_attack_tile(punit, x1, y1)) { /* thanks, Roar */
>         int vuln;
>         vuln = unit_vulnerability(punit, pdef);
> 
>         if (map_get_city(x, y) && /* pikemen defend Knights, attack Catapults
> */
>               get_total_defense_power(pdef, punit) *
>               get_total_defense_power(punit, pdef) >= /* didn't like > --
> Syela */
>               get_total_attack_power(patt, punit) * /* patt, not pdef */
>               get_total_attack_power(punit, pdef) &&
>               unit_list_size(&(map_get_tile(punit->x, punit->y)->units)) < 2
> &&
>               get_total_attack_power(patt, punit)) {
>           freelog(LOG_DEBUG, "%s defending %s from %s's %s",
>                   unit_type(punit)->name,
>                   map_get_city(x, y)->name,
>                   unit_owner(pdef)->name, unit_type(pdef)->name);
> 
>         } else {
>           int agress, bonus, coef;
> 
>           agress = reinforcements_value(punit, pdef->x, pdef->y);
>           agress += belligerence;
>           agress *= agress;
> 
>           bonus = unit_type(pdef)->build_cost;
>           if (map_get_city(x1, y1)) /* bonus restored 980804 -- Syela */
>             bonus = (bonus + 40) * punit->hp / unit_type(punit)->hp;
> 
>           /* arguable that I should use reinforcement_cost here?? -- Syela */
>           if (a && is_my_turn(punit, pdef)) {
>             coef = ((bonus * agress - unit_type(punit)->build_cost * vuln) *
> SHIELD_WEIGHTING /
>                     (agress + vuln) * SHIELD_WEIGHTING);
> 
>             /* no need to amortize! */
>             if (coef > best && ai_fuzzy(pplayer, 1)) {
>               freelog(LOG_DEBUG, "Better than %d is %d (%s)",
>                             best, coef, unit_type(pdef)->name);
>               best = coef; *dest_y = y1; *dest_x = x1;
>             } else {
>               freelog(LOG_DEBUG, "NOT better than %d is %d (%s)",
>                             best, coef, unit_type(pdef)->name);
>             }
>           } /* end if we have non-zero belligerence */
>         }
>       }
> 
>     } else { /* no pdef */
>       pcity = map_get_city(x1, y1);
> 
>       if (pcity && is_ground_unit(punit) &&
>           map_get_terrain(punit->x, punit->y) != T_OCEAN &&
>           pcity->owner != pplayer->player_no) { /* free goodies */
>         best = 99999; *dest_y = y1; *dest_x = x1;
>       }
> 
>       if (map_get_tile(x1, y1)->special & S_HUT &&
>           best < 99999 &&
>           could_unit_move_to_tile(punit, punit->x, punit->y, x1, y1) &&
>           !is_barbarian(unit_owner(punit)) &&
> /*          zoc_ok_move(punit, x1, y1) &&
>           !is_sailing_unit(punit) && */
>           punit->ai.ai_role != AIUNIT_ESCORT && /* makes life easier */
>           !punit->ai.charge && /* above line seems not to work. :( */
>           punit->ai.ai_role != AIUNIT_DEFEND_HOME) { /* Oops! -- Syela */
>         best = 99998; *dest_y = y1; *dest_x = x1;
>       }
> 
>       /* next to nothing is better than nothing */
>       if (is_land_barbarian(pplayer) && best == 0 &&
>           get_tile_infrastructure_set(map_get_tile(x1, y1)) &&
>           could_unit_move_to_tile(punit, punit->x, punit->y, x1, y1)) {
>         best = 1; *dest_y = y1; *dest_x = x1;
>       }
>     }
>   } adjc_iterate_end;
> 
>   return best;
> }
> 

Looks good. I will include your patch inside mine. What do you want for the
blurb

Petr Baudis Email pasky@xxxxxxxxxxx

Changed  ai_military_find_victim

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