Limiting out of depth monsters

[Hajo]

I want to limit out of depth monsters, particularly on the early dungeon levels.

I'm not quite sure if I found the right place, and also not quite sure if my new formula will work as intended. So I want to ask here. I'm Using the Angband 2.9.3 codebase, I hope a few of you will still remember that.

In the file monster2.c there is a procedure get_mon_num() which calculates a monster number appropriate for the given depth. It has a block:

		/* Occasional "nasty" monster */
		if (rand_int(NASTY_MON) == 0)
		{
			/* Pick a level bonus */
			int d = level / 4 + 2;

			/* Boost the level */
			level += ((d < 5) ? d : 5);
		}

I have changed this to:

		/* Occasional "nasty" monster */
		if (rand_int(NASTY_MON) == 0)
		{
			/* Pick a level bonus */
			int d = level / 5;

			/* Boost the level */
			level += ((d < 5) ? d : 5);
		}

The new code should not generate out of depth monsters for the first 5 levels if I understood right. Also have a more shallow curve for generating OOD monsters later. Do you think this will work as intended?

[Sirridan]

At level 5 it should generate a one level ood monster, or a level 6.

[Hajo]

Right. I started counting at 0, but that is town.

Right now I wonder if I can diff&patch my changes to Angband 2.9.3 into Angband 3.1.2v2 ... the overall code structure looks similar but I guess a lot of things have changed in between.

[RogerN]

Note that the last line of code ensures that no monsters are ever generated more than 5 levels OOD (I don't think this applies to vaults, though). This means that the formula has no effect after level 25 using your formula (and it has no effect after level 12 using the original formula).

[Hajo]

I'm not sure if I follow. The

level += ((d < 5) ? d : 5);

limits the level "boost" to at most 5 levels of the nasty monsters. But there can still be 5 level OOD monsters generated after 12 (or 25) levels?

[Sirridan]

I'm not sure if I follow. The

level += ((d < 5) ? d : 5);

limits the level "boost" to at most 5 levels of the nasty monsters. But there can still be 5 level OOD monsters generated after 12 (or 25) levels?

No, at 12 you can have a max ood of 2. That line can be rewritten like this, if you find the ternary operator (?) confusing.

if(d < 5)
    level += d;
else
    level += 5;

EDIT:

To be more precise, the level / 5 means that the max ood is one fifth the level, so a level 12 generates up to a 2 OOD monster, where level 25 generates a 5 ood. At level 60, level/5 is 12, but the line of code at the end limits it to 5.

[ekolis]

Why not use MIN to be really clear?

level += MIN(d, 5);

[Hajo]

To be more precise, the level / 5 means that the max ood is one fifth the level, so a level 12 generates up to a 2 OOD monster, where level 25 generates a 5 ood. At level 60, level/5 is 12, but the line of code at the end limits it to 5.

Yes. That is quite what I wanted it to do. Sorry if my writing was not clear enough.

[zaimoni]

Note that the last line of code ensures that no monsters are ever generated more than 5 levels OOD (I don't think this applies to vaults, though). This means that the formula has no effect after level 25 using your formula (and it has no effect after level 12 using the original formula).

Actually, there are two level-boosting blocks to be modified; the maximum OOD level boost is the same at DL25 and lower [10].

[Hajo]

In the original code there were two of such blocks directly behind each other, so the level boost could happen twice. Is this what you mean? Or is there a different location in the source that must be adapted too?

[zaimoni]

In the original code there were two of such blocks directly behind each other, so the level boost could happen twice. Is this what you mean?

Yes. I just wanted to make it clear that there was no change in maximum level boost, for those who don't sourcedive.

[Timo Pietilä]

Note that the last line of code ensures that no monsters are ever generated more than 5 levels OOD

That can't be right. I just recently encountered AMHD at ~1500' in non-vault room. That's about 10 levels OoD. Something odd in OOD code? Bug? In that same game I got WoG before any other dungeon books. Twice.

[Hajo]

In Angband 2.9.3 there were two of these code blocks behind each other. So there was a small chance that a monster got two 5 level boosts, totaling 10 levels OOD.

I haven't checked the current Angband codebase yet to see if this still is this way.

[Timo Pietilä]

In Angband 2.9.3 there were two of these code blocks behind each other. So there was a small chance that a monster got two 5 level boosts, totaling 10 levels OOD.

I haven't checked the current Angband codebase yet to see if this still is this way.

IMO hard limits for OOD monsters (and items) are not a good idea anyway. Just make it exponentially rarer the more OOD it is. Getting Ancient Red Dragon at 300' every now and then would give a nice spice to playing.

[Sirridan]

IMO hard limits for OOD monsters (and items) are not a good idea anyway. Just make it exponentially rarer the more OOD it is. Getting Ancient Red Dragon at 300' every now and then would make you nice and spicy.

Fixed

But agreed