Line of Sight and Line of Effect

[baberg]

but then that also means that the hallway situation means that while the two creatures in the hall have no cover, they do not have line of sight since every corner "touches" a wall. So you can't even see them so they are invisible (total concealment -5)? Seems a bit absurd.

If it seems absurd, then odds are you're doing it wrong.

Re-read LOS. "Touch" doesn't include "originates from", so the origination point and the destination point don't count as far as "touch" goes.

 

[Chris_Nightwing]

Actually the rule is specifically (pg. 280 PHB): "To determine if a target has cover, choose a corner of a square you occupy (or a corner of your attack's origin square) and trace imaginary lines from that corner to every corner of any square the target occupies."

In summary, choose the optimal corner of a square you occupy, and draw 4 lines (one to each corner of the enemies optimal sqaure for you to target - most cases the single square they occupy).

Now Line of effect is the one that does not have to use corners, just a line from your space to anyware on their space.

Now the situation you brough up Chris is an interesting one and certainly creates a strange movement.

Minwanderer I totally agree with you as well, but that means the text for Line of sight on page 273 and the picture for line of sight on 274 are both wrong, which I also agree seems to be the case. Once we get a few more agree responses I will post in the possible errata thread.

I was referring to the LOS rules. I really don't think I can explain the situation using ASCII diagrams but imagine something like this:

---
--X
---
X--
---
A--

Lay this out on a big grid and then figure out which squares person A can see from each of their corners, where X is a big square blocking block. Far north of my diagram there will be a position for person B out of A's line of sight, because A can only trace lines from their corners to determine what they can see. However, there will be a line just touching both pieces of cover that goes right through the middle of A, hitting none of their corners. This line, far to the north, will eventually hit a corner of a square that A can't see. B stands here. Thus results the asymmetry.

On the other matter of cover, because traced lines that run along an obstacle don't count (but it's not clear about touching corners) the only weird case seems to be a melee attack around a corner:

B-
XA

Here, A chooses their top right corner to determine cover and behold, there is none, despite A not being able to move to the square. This can be fixed by banning this attack or making it a special case of cover. Banning it solves the movement problem!

 

[Chris_Nightwing]

If it seems absurd, then odds are you're doing it wrong.

Re-read LOS. "Touch" doesn't include "originates from", so the origination point and the destination point don't count as far as "touch" goes.

Actually it's solved easier because LOS says "pick a corner of your space and trace an imaginary line from that corner to any part of the target's space" - not just one of their corners. This asymmetry results in a mess (see above!).

 

[hamishspence]

ranged attacks

It fits. in above Chris Nightwing described situation, your opponent does not have cover. you can see him. But, you cannot hit him with a melee weapon. Doesn't stop you hitting him with a ranged weapon.

 

[Chris_Nightwing]

It fits. in above Chris Nightwing described situation, your opponent does not have cover. you can see him. But, you cannot hit him with a melee weapon. Doesn't stop you hitting him with a ranged weapon.

I was hoping that was the case - where is the rule saying you can't hit someone in melee around a corner? I hope it's there!

 

[hamishspence]

sorry: error

the term should have been Total cover. Guy at diagonal doesn't have total cover, does have cover, but you can hit him for -2 penalty, even in melee.

EDIT: sorry again, by strict RAW the described situation: Y = YOU E = ENEMY
Y
XE

no cover at all since you can trace line to every corner. the sample pics in PHB were valid, but it turns out that that close to a corner there is no obstacle. hmm.

on the plus side, for ranged attacks, there are situations where one guy has cover, the other doesn't:
E
XXXXXXXXXXXXXXXXXXY

So you can hit him, no cover penalty, but he takes penalty against you.

 

[GoLu]

Has anyone accounted for the differences between the PHB and the DMG? It looks like in the PHB melee and ranged attacks use the same cover rules while in the DMG they use different rules.

Ultimately, this is going to be settled by the advice in the DMG which basically said "don't sweat it too much; it's not that big a deal" but having some idea of what was intended would be nice.

 

[hamishspence]

melee and ranged

Only difference is for melee: in PHB, no difference: some blocking doesn't always cause cover penalty. in DMG, ANY blocking at melee range causes cover penalty.

I'm guesing DMG for the time being: makes a little more sense to have wall corners make fighting a little harder. Done with a spiral staircase, we can play swashbucking style.

 

[omg_ryan]

melee vs ranged cover

I did a lot of reading on the "cover' thing. In the PHB the rules are incomplete. The PHB basically explains Ranged cover rules. The DMG has better explaination. It explains the rules for Ranged cover and Melee cover happen to be completely different. Notably in the situation...

AX
XB

A and B can attack each other with cover, melee (while it would be no cover for ranged), actually don't quote me on that, I don't have the DMG right now... Still, My suggestion is read the DMG again, I think it makes cover clear. Well except for one thing I'm still a bit unclear on --- how do you handle things that don't fill up the entire square? For example, trees don't take up 5 foot squares (at least in reality, game mechanics-wise they might need to). so how do you do the following:

t A t
t t t
t B t

Or the PHB has an example of cover where "a player is in the same sqare as a small tree".

FYI: The way I'm currently interrupting it is there are the technical cover rules, which are well explained in the DMG. Then there are the "judgement" rules, like "in the same square as a small tree", which need to be used as well, and also can account for things that don't fill entire squares. Both the technical and judgement need to be considered when determining cover.

Haven't read about LOS yet, so I can't make any comments on it.
Thanks,
Ryan- www.openmindgames.com