[Freeciv-Dev] Re: new version of ai evaluation of defense buildings patch (PR#1362)

[Raahul Kumar <raahul_da_man@xxxxxxxxx>]

--- "Per I. Mathisen" <Per.Inge.Mathisen@xxxxxxxxxxx> wrote:
> CHANGES
>  - fixed off-by-one bug spotted by Markus L
>  - fixed fake cacheing spotted by Greg B
>  - renamed lots of stuff to better conform with impr. gen.
>  - added evaluation of non-nuclear missile threat (low threat estimate)
>  - doesn't get worried about invasions from non-transporting ships anymore

The patch looks good. It should go into CVS. A few minor quibbles that can be
implemented in your sequel. NOTE: Per does not have to do this. Just some nice
optional extras.

> FIXME (can wait until after cvs inclusion)
>  - should try to estimate how strong enemy needs to be to be a threat to
>    our defending units (now anything over 1 attack power is a threat)
>  - also increase threat potential if above a certain % higher att power
>    than our average defense power
>  - not capable of realizing grave danger from sea. when starting an ai
>    only game at techlevel 50 this shows clearly. (still, better than
>    unpatched ai.) see point above (need to recognize superior threat
>    from battleships earlier).
>  - despeartely need a concept of oceans to properly evaluate sea threats
>    (stop building those STUPID coastals right next to a freaking 1x1
>    pond!)

There is an ocean implementation available today. Corecleanups 13.
 
> +  FIXME: We should try to find the lowest common defence strength of our
> +  defending units, and ignore enemy units that are incapable of harming 
> +  us, instead of just checking attack strength > 1.
> +**************************************************************************/

Should consider hps as well, not just attack strength. Greg's approx would 
be good here.

> +void ai_eval_threat_init(struct player *pplayer) {
> +  int i, nuke_units = num_role_units(F_NUCLEAR);
> +  bool got_nukes = FALSE;

I have to admit the nuke units are the only change I can spot that is impr-gen
friendly.

> +    if (pplayers_allied(pplayer, aplayer)) {
> +      /* Just allies, we don't trust peace treaties _that_ much */
> +      continue;
> +    }
> +
> +    city_list_iterate(aplayer->cities, acity) {
> +      /* The idea is that if there aren't any hostile cities on
> +         our continent, the danger of land attacks is not big
> +         enough to warrant city walls. Concentrate instead on 
> +         coastal fortresses and hunting down enemy transports. */
> +      int continent = map_get_continent(acity->x, acity->y);
> +      pplayer->ai.eval_threat.continent[continent] = TRUE;
> +    } city_list_iterate_end;
> +
> +    unit_list_iterate(aplayer->units, punit) {
> +      /* If the enemy has not started sailing yet, or we have total
> +         control over the seas, don't worry, keep attacking. */
> +      if (is_sailing_unit(punit) && is_ground_units_transport(punit)) {
> +        pplayer->ai.eval_threat.invasions = TRUE;
> +      }
> +
> +      /* The idea is that while our enemies don't have any offensive
> +         seaborne units, we don't have to worry. Go on the offensive! */
> +      if (unit_type(punit)->attack_strength > 1 && is_sailing_unit(punit)) {
> +        pplayer->ai.eval_threat.sea = TRUE;
> +      }
> +
> +      /* The next idea is that if our enemies don't have any offensive
> +         airborne units, we don't have to worry. Go on the offensive! */
> +      if ((is_air_unit(punit) || is_heli_unit(punit))
> +           && unit_type(punit)->attack_strength > 1) {
> +        pplayer->ai.eval_threat.air = TRUE;
> +      }
> +
> +      /* If our enemy builds missiles, worry about missile defence. */
> +      if (unit_type(punit)->attack_strength > 1 
> +          && unit_flag(punit, F_MISSILE)) {
> +        pplayer->ai.eval_threat.missile = TRUE;
> +      }

You might want to consider making diplomats/spies defensively as a result of

if unit_flag(punit, F_DIPLOMAT) {
        pplayer->ai.eval_threat.spy = TRUE;
      }

But that's strictly optional. You might even make them as a result of

if (is_sailing_unit(punit) && is_ground_units_transport(punit)) {
        pplayer->ai.eval_threat.invasions = TRUE;
        pplayer->ai.eval_threat.spy = TRUE;
      }

To prevent the typical sneak in spies off transport trick.


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