Bug Alert, Shooting

Firstly, I will follow Lorenzo's clarification that visibility lines cannot cross. Then, as GC said, it makes nonsense of the requirement that the visibility lines are unobstructed if the visibility lines can go through the firing unit or other enemy units than the target unit. So, it is down to whether the target unit itself blocks the visibility lines.

Zippee, I can understand your frustration with the idea that a unit can't fire at a unit directly in front of it. I can see that using the rear corner to define visibility lines gets out of that difficulty. But beware of the law of unintended consequences. Consider the diagram below (if my diagram works)

--444444-
SSSSSS


--EEEEEEE

You can draw a line from the front right hand corner (in the diagram) of E to the front right hand corner of 4. Given a suitable separation, you can draw a line from the front left hand corner of E to the right rear corner of 4 (I've tried it). So if we take your interpretation, E can shoot at 4. That despite the S covering more than half the front of 4 (and indeed more than half the front of E). Note that the shooting priorities don't help as E is more frontal than S for 4.

That seems to me a more unlikely outcome than to say that B can't shoot in the original example. So if I apply the idea that visibility lines can be drawn to a rear corner of the target unit, I think I need to change the shooting priorities or something else to avoid other oddities. Occam's razor?

I'm not being affected by DBM or DBA since I've never played those rules. I suspect any set of rules will produce some odd effects occasionally, and trying to eliminate them will just produce other oddities. Is this one we have to live with?

RogerC

RogerC wrote:
So if we take your interpretation, E can shoot at 4. That despite the S covering more than half the front of 4 (and indeed more than half the front of E). Note that the shooting priorities don't help as E is more frontal than S for 4.

That seems to me a more unlikely outcome than to say that B can't shoot in the original example.

Is this one we have to live with?

RogerC

I assume E and S are friends otherwise TPs would certainly come into play. I'm afraid I don't follow your comment " E is more frontal than S for 4" - if E is shooting and S is a friend how does this matter? If S is not a friend then it must be the target of E. S is without doubt more frontal for 4 but as only E is shooting it doesn't make any difference.    

Anyway E shoots at 4 which is partly/mostly hidden behind S.

IMO whilst this is extreme, it's not much more extreme than the example in 6.4 where blue T can choose to shoot at red B which is barely in arc or LOS.

Allowing E to shoot at 4 which it can at least see part of is less of an issue to me than disallowing B shooting at 3 which is wholly and directly to its front.

This is also a precise and unusual situation that I suspect is far less likely to accidentally happen on the table than the OP and nigh on impossible once you add other units into the situation. Though that's impossible to quantify.

Apologies, I wasn't clear.

S is a friend of 4. So it looks like S has been positioned to protect 4 from shooting. However, the shooting priorities refer to the most frontal unit. I should have said 4 is more frontal for E than S, so 4 is the priority for E if 4 is visible. That may seem odd but in my diagram S occupies 4/6ths of E's frontage whilst 4 occupies 5/6ths. Visibility and 'most frontal' seem to be two separate tests.

It looks like we just disagree about which situation we most want to avoid. I'm not sure my situation is less likely than the original one, and if E can shoot at 4, the value of skirmishers as protection is much reduced.

As I said, Zippee, I can understand why you are uncomfortable with the idea B can't shoot at 3. I just think that your solution creates as many problems as it solves. We'll just have to disagree, at least until there is a ruling from Lorenzo.

RogerC

You may need to reconsider your interpretation of ' most frontal ' Roger . Feel free to hit me over the back of the head if I'm wrong       going off your diagram ..... S has to be the target . If I'm wrong then we in our group have been doing things incorrect from the beginning.

If however S are skirmishers then S can be ignored  and 4 can then be targeted with half the dice.

Think Zippee has also the same interpretation.

Yes Tarty I do - If S are enemy they are the TP for E (if they are Skirmishers they can also be ignored if wished but that may be overcomplicating the plot).

There has already been much debate on the clarity of the term "most frontal" - I think this proves it's not the best of phrases [in English]

Well, I'd taken the 'most frontal' as the unit which lies most to the front of E, as per http://impetus.forumsland.com/impetus-about3439.html&highlight=frontal
In my example, 4 occupies more of the front of E than S, looking directly in front of E

Of course, if visibility lines can't go through the target unit, 4 is not visible, and the issue doesn't arise. But if it is visible, isn't it the most frontal? If E was moved slightly to the right in my diagram, so could 'see' the right side edge of both 4 and S (lines to the right front and rear corners of 4 from the front two corners of E), wouldn't 4 then be the most frontal target?

How are you interpreting 'most frontal'? I'm considering the box defined by the forward extension of the sides of E, and asking which of 4 and S extends across more of that box. Are you ignoring the part of 4 overlapped by S? My understanding is that if a unit is 'visible' overlaps don't matter when considering 'most frontal'.

As another example of oddity, can 3 shoot at B in the original example? If visibility lines can go through the target unit then I think the right corner of 3 can see the front right corner of B and the left corner of 3 can 'see' the right rear corner of B. so 3 can (indeed must if within 15U) shoot at B rather than A or C. I think there is no doubt B is most frontal for 3. And that would be true, at least for some angles and depths of A and C even if B was wholly behind the rear edge of A and C. So apparently I must shoot at a unit behind the front line. Can that really be right?

This is getting more complicated than I'd thought. To my mind, it is only if visibility lines can go through a target unit do these oddities of 'most frontal' arise. I can't say I've had a problem before.

RogerC

This is getting all to complicated, I'm embarrassed at having raised the issue.

Just to summarise, this is not a show stopper, just a rare configuration that can occur, and as has been pointed out, there are work arounds. However it is a bug that I think can be easily resolved. In my original description of the problem I simplified the situation for the sake of ascii art, in the actual game play my units were not shoulder to shoulder, but separated by about 1U. There was a gap wide enough for a cavalry regiment + press corps to charge through, so it rather emphasised the oddity that shooting was very nearly illegal. I should also mention that there had been no attempt at "gamey" play on either side, the situation was the result of recoils / follow-ups and breaks in contact.

Yes, the shooters could advance to clear their arcs, but why should they? They may be defending a hill or advantageous ground and not wish to be drawn forward. An advance may bring them into the reaction zone of their target, or the movement penalty neutralise the shot.

Just to confuse the situation further, imagine if enemy base 4 was not present, then a shot would be legal. It is the presence of 4, beside the obvious target 3, that blocks the shot. It would not even need to be fully in line, just enough to block line of sight to the rear corner of 3. An enemy unit should not prevent shooting, not without becoming a target itself.

I agree that crossing lines, or lines that can pass through target units, create as many problems. So my proposal would be to add a second "or" clause to the shooting visiblity rule, to include a target within the uninterupted parallels of the shooting unit.

Would that work?

TD

RogerC wrote:

Of course, if visibility lines can't go through the target unit, 4 is not visible, and the issue doesn't arise. But if it is visible, isn't it the most frontal? If E was moved slightly to the right in my diagram, so could 'see' the right side edge of both 4 and S (lines to the right front and rear corners of 4 from the front two corners of E), wouldn't 4 then be the most frontal target?

How are you interpreting 'most frontal'? I'm considering the box defined by the forward extension of the sides of E, and asking which of 4 and S extends across more of that box. Are you ignoring the part of 4 overlapped by S? My understanding is that if a unit is 'visible' overlaps don't matter when considering 'most frontal'.RogerC

"Most Frontal" requires clear and unfettered base edge. So yes we ignore the part of 4 overlapped by S. Say E has an 80 width, S covers much of it (say 50), 4 covers a bit more (say 60) but only the (say 10) frontage that is not covered by S counts. in other words more than one unit cannot be claiming the same "frontage" against a unit - the closest takes precedence. Not that this is stated anywhere but AFAIK it's the standard under which we have always played.

The further right you move 4 to gain "frontage" then the less of an issue the LOS quirk is surely?

RogerC wrote:
As another example of oddity, can 3 shoot at B in the original example? If visibility lines can go through the target unit then I think the right corner of 3 can see the front right corner of B and the left corner of 3 can 'see' the right rear corner of B. so 3 can (indeed must if within 15U) shoot at B rather than A or C. I think there is no doubt B is most frontal for 3. And that would be true, at least for some angles and depths of A and C even if B was wholly behind the rear edge of A and C. So apparently I must shoot at a unit behind the front line. Can that really be right?

When I set up the situation, yes 3 could see and thus shoot at B - I don't see that as an issue as it's certainly most frontal. Now that you don't have to shoot at the closest within 150 it becomes the only viable target - not sure that's so great. But I never really got why that clause was dropped from the new TPs.

There are always going to be fringe circumstances in any rules set. So oddities will arise. In RogerC's example the target is 4 not S since how close the firing unit to the target is immaterial when firing under 15U. We could come up with some more complex LOS and firing priority rules but I'm not in favour of that personally. Overall I think Impetus firing works fine and I am willing to accept the oddities of Aurelius' and RogerC's examples to keep it such.

I don't think you need be embarrassed at raising the issue Aurelius. Actually your example is quite interesting and it helps clarify the rules for me. There are lots of little things in Impetus that I question at times but overall the system works fine. I'd like to ask Aurelius if B should be able to shoot at 3 can 3 return fire to B and ignore in A in your thinking?

Aurelius wrote:This is getting all to complicated, I'm embarrassed at having raised the issue.

Just to confuse the situation further, imagine if enemy base 4 was not present, then a shot would be legal. It is the presence of 4, beside the obvious target 3, that blocks the shot. It would not even need to be fully in line, just enough to block line of sight to the rear corner of 3. An enemy unit should not prevent shooting, not without becoming a target itself.

I agree that crossing lines, or lines that can pass through target units, create  as many problems. So my proposal would be to add a second "or" clause to the shooting visiblity rule, to include a target within the uninterupted parallels of the shooting unit.

Would that work?

TD

Don't be embarrassed, these situations are precisely why the forum exists, so that things can be thrashed out in gentlemanly discourse, the product of which gives Lorenzo much to work with for getting 2ed right

BTW on that thought - thanks to all for keeping things civil - legion are the forum where this would have crashed and burned by now

Previously the TP would have dictated that if 3 shot, then A must be the target - "closest within 150 and within arc". Now it's B "most frontal if partially within front projection". I understand why the "most frontal" was brought in - to avoid the extreme angle shooting as in the original 6.4 example but I'm not really sure it cured much more than it generated.

All such geometric situations will cause problems, we must necessarily choose the least evil option. Bear in mind that this gets infinitely worse when we stick CL with 360* arc in the place of what I assume are T units in the examples above.

In the OP if we assume 2, 3 and 4 are shooters then who do they shoot?
2 shoots A this seems clear; 4 shoots C this also seems clear even though part of the unit is in front of B (C is closer and more frontal). I'm sure no-one would dispute that as sensible/desirable.

However who does 3 shoot at, I can see three options:
1) 3 shoots at A because it is closest, within forward projection and visible
2) 3 shoots at B because it is "most frontal" within forward projection and visible*
3) 3 can't shoot because A is in the way of a clear shot

* Yes I know we have debated LOS as dictated by 6.4 but by any real world
standard B is visible to 3.

By return if A, B and C shoot, again it's pretty clear that A shoots 2 (most frontal), C shoots 4 (most frontal / only target); B either shoots at 3 (most frontal) or can't shoot because of a LOS quirk.

The closer B and 3 are to each other, the more it feels right that they shoot each other, the more you drop B back to 'behind the line' the more it feels wrong.

If A and 3 were friendlies we wouldn't want 3 to be able to shoot B because A would be in the field of fire. But if A and B are both enemy we don't care so much about stray casualties.

So I think there is mileage in looking at a TP that says something like:
"The priority target is the enemy unit that occupies most of the shooter's frontage. If more than one enemy unit occupies equal frontage, then the closest is the priority, if both are equally close then [use the rule/roll that offsets them right/left as they shouldn't be so perfectly lined up].

If any friendly unit occupies any of the shooter's frontage then the shooter cannot shoot unless the enemy are closer.

If no unit is within the shooter's frontage then the enemy unit that has the most base area within the fire arc is the priority provided LOS can be drawn from the front two corners of the shooter's firing edge to any two corners of the target without either crossing each other or any obstacle [including the target base]"

Gaius Cassius wrote: In RogerC's example the target is 4 not S since how close the firing unit to the target is immaterial when firing under 15U.  

AFAIK only the frontage of 4 directly in front of E counts, not that which is behind S. As long as S covers more of E's front than does the exposed part of 4 then S must be the target. I've never met anyone who played it differently.

Zippee wrote:

Gaius Cassius wrote: In RogerC's example the target is 4 not S since how close the firing unit to the target is immaterial when firing under 15U.  

AFAIK only the frontage of 4 directly in front of E counts, not that which is behind S. As long as S covers more of E's front than does the exposed part of 4 then S must be the target. I've never met anyone who played it differently.

Interesting point Zippee. I made up a quick photo of what RogerC was laying out. A unit of CP masked by a friendly T unit being fired on by an enemy T unit. The firing T unit has LOS on both targets and can draw a line from both front corners to two corners on both enemy units. So no problem there.

The CP occupies more of the frontal zone of the firing T unit. If we consider only the portions of the stand "exposed" to the firing T unit then it is the defending T unit that is in more of the frontage of the firing T unit. Which unit is the target? According to you it would be the T unit and according to RogerC it is the CP. We play it like RogerC and a literal reading of the rules would tend to support his interpretation. There is nothing in the rules that talks about only the exposed parts of a unit being considered when calculating frontage. On the otherhand, if this is what Lorenzo wants I'd be fine with that. This is where a clarification from Lorenzo
would be helpful.

As an aside, it doesn't come up that often because of how the angles work. The more in RogerC's example that S covers 4 the more difficult it will be for E to get corners on 4 and the more S uncovers 4 the more of 4's frontage is exposed to E.

Impetus by Eusebeia2002, on Flickr

Yes, a gentlemanly discussion.

And yes, it looks like we need a clarification from Lorenzo about overlaps and 'most frontal'. As GC says,it doesn't come up that often. Does it also affect which is the main unit for melee? Imagine two attacking units inclined to the defender with one attacker extending behind the other. Do I consider the overlap when deciding which attacker is main and which support?

Zippee, I saw your modified TP and thought 'that's a good solution'. It solves all the oddities we've been talking about. No doubt it'll set up a few of its own.

Three questions though. Presumably your second clause about friends in the frontal projection only applies to the first clause about shooting at enemies in the frontal projection, not the third about shooting at an enemy elsewhere in the fire arc? Otherwise a friend just in my frontal projection will stop me firing at an enemy well off to the side. Secondly, in your third clause, if I have two enemies wholly in the fire arc but outside the frontal projection, presumably I have to fire at the closest? Thirdly, can I still choose between closest and frontal, if all the enemies are outside 15U? Would the second clause still apply (I see no reason why it shouldn't).

The restriction on shooting when friends are in the frontal projection is a real change. At the moment, if an enemy is visible, I can shoot at it even if friends are right next to it.

This discussion has lots of interesting points. I'm glad Aurelius started it.

RogerC

Gaius Cassius wrote:
Which unit is the target? According to you it would be the T unit and according to RogerC it is the CP. We play it like RogerC and a literal reading of the rules would tend to support his interpretation. There is nothing in the rules that talks about only the exposed parts of a unit being considered when calculating frontage.

All true - we've just always played it the way we have. It seemed sensible.

As many may recall from the old forum I was never that impressed with the change, I think it is poorly described and doesn't address what it needs to.

I'm sure Lorenzo knows what he wants it to be but I struggle to understand

RogerC wrote:
Zippee, I saw your modified TP and thought 'that's a good solution'. It solves all the oddities we've been talking about. No doubt it'll set up a few of its own.

Three questions though. Presumably your second clause about friends in the frontal projection only applies to the first clause about shooting at enemies in the frontal projection, not the third about shooting at an enemy elsewhere in the fire arc? Otherwise a friend just in my frontal projection will stop me firing at an enemy well off to the side. Secondly, in your third clause, if I have two enemies wholly in the fire arc but outside the frontal projection, presumably I have to fire at the closest? Thirdly, can I still choose between closest and frontal, if all the enemies are outside 15U? Would the second clause still apply (I see no reason why it shouldn't).

The restriction on shooting when friends are in the frontal projection is a real change. At the moment, if an enemy is visible, I can shoot at it even if friends are right next to it.

This discussion has lots of interesting points. I'm glad Aurelius started it.

RogerC

Well I thought it a starting point

Q1 - No I thought that was a simple catch all - if I have friends in my frontal zone they stop me shooting unless the target is closer. Simple, easy to explain and justifiable I think.

Q2 - Possibly, but I was thinking the one with most base in the firing arc. But really either would be fine.

Q3 - I had rather ignored the artificial distinction between short and long range. I see no reason why it should be different. Maybe as the distance increases it just gets more difficult to adjudicate so it's easier in practice to allow choice. I'm not against it but I don't really see why shooting at 200 should be technically different from shooting at 100.

Yes it is but I think it's a better way of describing the situation than geometry and lines. I have no issue with shooting multiple enemy units and assuming that one is the main target - I think commanders would be hesitant to shoot when friendly units are in the way (except Longshanks of course, maybe he can have a special rule )

I'm sure it has its own bugs - that's what you lot are for

Ok well this is interesting. The shooting ' doctrine ' as put forward by Roger's - most frontal example has never been interpreted like that around here.
Actually I don't think anyone has even thought of it
I can see what Roger and GC is saying technically and yes reading the rules I can see how it could be read to mean that....but for me it would seem a little strange.  
I'm definitely in Zippee's camp on this one.
Being made to shoot at 4 instead of S does not make sense to me, S would have to be the target in my book.
This would also have huge consequences with the effectiveness of screeners as well wouldn't it ? ...gosh everything would have to be lined up just so ! ... all very technical and DBXish . Uuuurgh the thought of it .

Not sure it is quite that bad Tarty! It only applies in a very few cases since in practice S either covers 4 so well that there aren't any firing lines to be had or S is over enough the other way that 4 occupies the largest frontage of E. If you look at my picture you'll see that S and 4 occupy almost the same frontage for E. Move S a bit to the left and now 4 definitely occupies the larger portion of E's frontage. Move the S a bit to the right and S definitely has the great frontage for E and E has no firing lines to 4's corners.

If visibility lines can't go through the target unit, then shooting at a unit behind another will be very rare. In my example, E cannot see two corners of 4, if it isn't allowed to 'see' the right rear corner through 4, so S must be the target. And if you move E to the right so that it can see the two right corners of 4 without the visibility lines passing through 4, then the overlap with S is much decreased and in nearly all situations 4 will be the most frontal irrespective of overlap.

That is why I think the questions of visibility and overlap are related - if you allow more visibility, as with Zippee's original interpretation of visibility lines, then more screened units are visible and they become targets (compulsory within 15U) if they are 'most frontal'.

As usual with Impetus, one change affects other situations. I'm still thinking about Zippee's proposed clarification. The idea that friends in the frontal projection may prevent firing may be a major change, particularly when firing units are partly screened by friendly skirmishers.

RogerC

Gaius Cassius wrote:

"I'd like to ask Aurelius if B should be able to shoot at 3 can 3 return fire to B and ignore in A in your thinking?"

My first thought was yes. But then on reflection there are plenty of situations when a base could be out of arc/range or lower priority. So I would apply the same rules for sight lines etc. to determine whether shooting could be returned. In most cases of course it would not be an issue, as unless on opportunity / reaction the option would not be available.