targetting and LOS

[Pete Mack]

@magnate--
I thought that d_m was on to something when he mentioned walls being visible in the full square (according to the DFOV.)

As I said, albeit very unclearly, I think that using permissive FOV for visibility but limited FOV for targetting is a good idea; it's very much in line with the current angband model.

[PaulBlay]

My last post was an outline of an argument that if you want all of those properties, then you cannot also have as a 5th property an expanding cone of shadow from a pillar. The 5 properties together produce a contradiction.

Which property does real life not have? Because (without moving back and forth within the square) real life does have an expanding triangle of obscured area behind a pillar.

Seriously though, this discussion has broken the limits of what can be readily followed in newsgroup forum format. I think it needs a format like, for example, wiki where you can have links between sections, editing out of bits determined to be incorrect and such. (There are other, better, formats but they take money and training ;-)

[zaimoni]

The problem is that I don't know how to draw those pretty pictures. Also, I was trying to make an argument that applied to all forms of expanding cones, not just a particular one, so there isn't a specific example to show.

###WXY##########
................
................
............Z...
................
................

Consider the shadow behind X when you view from W, assuming X is a wall square.
The model needs to cope both with Y being another wall square or an entrance.
Let's say that Z is in that shadow. Then W cannot see Z. Then Z cannot see W.

So a square well in the interior of the room cannot see all of the walls of the room.

Counter-example: Zaiband.

Zaiband has expanding cone shadows, and does allow any square in the middle of a rectangular room to see all of the walls.

If the projectability/visiblity algorithm was or-symmetrized (it currently isn't for gameplay reasons, but it's a rote change; it might even be worth a birth option), the left-wall example would have the left wall not-visible.

[aeneas]

Which property does real life not have?

Real life and Angband are remarkably different. I mean- we can leave aside things like the fact that I am only very rarely attacked by veterans and mercenaries on the way to the store. That's a trivial distinction. But Angband is not like real life mostly because our circles and ellipses translate to squares and rectangles in Angband.

Angband has always followed a "worse is better" philosophy in terms of LOS and targeting. The implementation is simple, but the interface is a bit tricky. I think this approach has worked out pretty well, but... it does have a few quirks. The biggest problem is that it's not symmetric. That might be a feature, or it might be a bug. Anyway, if you want to fix that you could just steal the code from NPP where targeting is symmetric. Or you could decide that if you can see it you can target it. But if you do either of those things I think you might want to re-balance hounds.

Then you're going to have a certain number of complaints about characters lost to misunderstanding changes in LOT. As my first exhibit I would like to offer this dump: http://angband.oook.cz/ladder-show.php?id=6831. Level 50 character (rare time investment for me- I usually go for it at clvl 45 or so in NPP), more than ready to win even in NPP, died because I confused V targeting and NPP targeting.

I think the current V LOS and targeting system works pretty well as a gameplay mechanic. It has one problem, and that's the fact that you can tunnel to a spot where you can kill immobile monsters with no chance of retaliation- this is mainly a problem with the emperor Quylthug. Anyway this can be fixed by making a change that should have been made long ago- all walls except for a select few that open vaults should be permanent. I suspect that one release like that would lead to a general demand for a re-balancing of summoners, which would be good, but that's another post.

Anyway, I think LOS/LOT ought to be treated very conservatively, if only for the sake of us old-timers. I have a pretty good intuition, at this point, as to who can target me even in very complicated corridor layouts. I'm going to be pretty annoyed if I'm suddenly getting whacked by Vecna when I'm sure I'm safe. I can put up with that in NPP, but in V... well, at the very least, if it gets changed, it would be best if it only gets changed once.

I don't want to have to carry around more than a few LOT algorithms in my head. And I think that many implementers underestimate the amount of calculation that good players do. We're always thinking things like "OK, lots of Balrogs, but I have immF.. but those Osyluths.. let's add up the potential damage, and assign some probabilities here- I think I can kill Lungorthin this round, but.. will the Osyluths get me? Hmm- that one can't target me, so I'll live through it even if the rest all do their their worst- unless they really do their worst, in which case I am dead- but the chances of that are like 2.5%. Fuck it, let's smack Lungorthin one more time." The thing is that if that extra Osyluth can target me the chances that I'm dead might rise to something like 30%, or more.

Preserving the ability to do that kind of calculation is far more important than making Angband correspond to "the real world" in some fashion. The world is round. Angband is square. 'Nuff said.

[PowerDiver]

Which property does real life not have? Because (without moving back and forth within the square)

You cannot have any restrictions on what happens within the limit of your measurement.

So long as your basic unit is 10' wide, you have to allow for an eyeball-to-eyeball width of 10', or movement around, or however any lunatic might think about it. If you want to rule those out, you have to change the measurement. Handwave all you like, but your arguments are usually doomed to be self-contradicting if you try to apply common sense on a grain that is finer than your smallest unit of measurement.

A different but [I think] equivalent perspective is that a monster being in a square does not specify a location, but rather a set of inequalities describing that monster's center. Most natural is to define to be within 5' horizontally and vertically from the center of the square.

A valid model needs a representation for every possible position for a monster. Real life has real-valued positions. If you cannot say where a monster who is centered at (3.3, 11.2) is represented on your integer coordinate system in your model, then you are failing to model real life, and you likely have a problem that will lead to inconsistencies. A particular point in your integer model needs to represent a range of real-valued positions.

This applies to pillars too, and is why I had no particular problem with radius-0 pillars in my initial suggestion, although most of you probably thought I was crazy. You fit as many desirable model properties together as you can make consistent, but you will always have to stop before you are satisfied, because an approximation never has all of the properties of the real thing.

[PowerDiver]

If the projectability/visiblity algorithm was or-symmetrized (it currently isn't for gameplay reasons, but it's a rote change; it might even be worth a birth option), the left-wall example would have the left wall not-visible.

You are agreeing with me. In order to add the property of symmetry, you have to remove the property that an interior square can see the wall.

[Nick]

Just a quick question - what problem are we trying to solve here? Is it hockey stick/knight's move attacks? Is there anything else?

[PaulBlay]

Just a quick question - what problem are we trying to solve here? Is it hockey stick/knight's move attacks? Is there anything else?

I don't think we know anymore. (Which is another reason I think that forum threads aren't up to this). I don't even know where my "five properties" post is and there are fifteen pages to look through.

[PowerDiver]

Just a quick question - what problem are we trying to solve here? Is it hockey stick/knight's move attacks? Is there anything else?

The problem of the hockey stick suggests the goal of symmetric LOS. A separate goal is visible equivalent to targetable. These have not been proven to be good goals, but they have some appeal at first glance.

The overriding restriction I suggested is that you should see a death mold a knights move away in the situation

m.
.#
#@

so you don't step next to it, but I'm not sure even that has universal appeal. At least I haven't noticed anyone complaining about it yet.

The game is in flux, and if sweeping changes are coming, now is the time to consider them. The drops are currently broken, and game balance in general is off, so it's perhaps less of a burden to break something else now than it may be in the future.

I suppose the point of this thread was to discuss what the LOS/targeting goals should be. I suggested a particular model/implementation to show an example of what could be achieved, but I probably got too excited and presented it as direction rather than an example. In my defense it is a cool model. Later someone posted a link to a better model. Then we started bickering over details related to visibility blockage due to a single # inside a large open area.

[aeneas]

Just a quick question - what problem are we trying to solve here? Is it hockey stick/knight's move attacks? Is there anything else?

I think that's about it. And I think it is a feature when it comes to monsters that move. Hounds are balanced with that in mind. If you can't kill them in one shot they can still overwhelm you.

But there's another problem- you can dig out a sequence of knight's moves, or an ASC. I don't ever dig to gain a tactical advantage- I think it is really cheap. I think that almost all walls should be permanent, and I play as if they are.

I don't know how long you've been playing bands, but I wonder if you remember Lev. He was King of Bands at one point. He won Z in <50K by abusing every game mechanic he could. I'm still pretty impressed with Lev- he was a very good player. But I have a different philosophy- I only abuse a certain number of things .

One of the big questions about Angband is what constitutes abuse. As far as I am concerned _any_ digging meant to establish a better tactical position is abuse. Yeah- it's in the game. But it allows you to reduce the worst enemies in the game to walking treasure boxes. I don't consider any win that used ASCs at any point a real win.

Every once in a while I wonder what I could do if I really used everything in the game. I could stair-scum- but I guess that's meaningless when scrolls of Deep Descent show up in the BM. I could kill big summoners in ASCs- I guess that is actually done pretty frequently. But I'm a purist about this sort of thing. I only remove stone in order to get at vaults. And I think V would be better if that were the only case in which you could remove stone.

[PaulBlay]

The overriding restriction I suggested is that you should see a death mold a knights move away in the situation

m.
.#
#@

so you don't step next to it, but I'm not sure even that has universal appeal.

Should you even be able to step diagonally between two walls like that?

[aeneas]

Should you even be able to step diagonally between two walls like that?

You have to be able to, given the current dungeon generation routines. soreha atarimaedarou..

[PaulBlay]

You have to be able to, given the current dungeon generation routines. soreha atarimaedarou..

I think everything is up for debate - including dungeon generation.

I think there are only a few vaults where you have to be able to go though gaps like that, 違いますか。

[aeneas]

I think everything is up for debate - including dungeon generation.

I think there are only a few vaults where you have to be able to go though gaps like that, 違いますか。

Chigaimasu yo. There is, for instance, a very common small vault that requires that you pass through that sort of gap. Beyond that you'd have to really rethink Destructed areas, and they are more important than you might think... they're a pain in the ass under most circumstances, but they are very useful for killing certain uniques. Including Morgoth....

You really would have to do some hard thinking to eliminate that.

[PaulBlay]

So you don't think you should be able to see the outline of a large lit room when you enter it adjacent to a wall?

This is a key question. If the M horizontally next to a # has an expanding cone of shadow, it cannot see the @. By symmetry, the @ cannot see all of the walls of the room. There is no way around this without changing one of those properties.

I missed this one (I think).

I don't think you should be able to see monsters in the walls for the whole of a large lit room when you enter it adjacent to a wall. I see no reason why walls can't be "special cased" to display when adjacent to lit, visible, floor tiles. Exact details would need to be decided on.