Line of sight & cover along walls and around pillars

In these scenarios in DnD 3.5, do I have line of sight to the target? If so, does the target have cover?

(A = attacker, W = wall, T = target, . = empty square)

Along a wall:

W W W
A . T
. . .


Across a pillar:

. . . . .
A . W . T
. . . . .


Between pillars:

. . W . . . T
A . . . W . .

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It's an interesting question, but it's also an oddly specific case. I wonder: what prompts this question? – Emrakul Nov 19 '13 at 23:54
I played D&D 4e before and now I'm trying to learn the rules of 3.5 and I remembered this was a problem in 4e and when I checked the Player's Handbook for 3rd, I didn't find anything. What confuses me is that rules for cover (and line of effect) say that even touching a tile is enough to block a line. A follow-up question, if I may: 2x2: First row: E., Second row: EA, where E=enemy creature, A=attacker. Is it correct that the upper enemy has cover from the attacker (if he were using ranged attack)? – Petr Hudeček Nov 20 '13 at 0:01
Technically, as far as I know, yes, that creature would have cover from a ranged attack. However, I've never actually seen it played that way. – Emrakul Nov 20 '13 at 0:10
I could've sworn there were rules for pillars somewhere, in the DMG section on forests (for small trees) or something... If I had my DMG here, I'd check. More importantly, whether a pillar blocks line of sight should entirely depend on the width of the pillar; A three-inch-wide decorative pole is going to provide partial cover, at best. – GMJoe Nov 20 '13 at 4:26
@GMJoe I had that thought too, and then realised that the OP is using "wall" and "pillar" interchangeably, so they're talking about 5'x5' square "pillars" as are often seen in dungeons. – SevenSidedDie Nov 20 '13 at 16:18

In the first case, it is clear that the attacker has line of sight. The attacker is totally unobstructed from the target.

In the second case, the attacker does not have line of sight, and cannot attack the target with a sight-dependent attack. The attacker could, however, move to the side, which would allow them to attack the target (whou would have cover).

In the third case, there is line of sight, as the attacker can see the target's square. The target does, however, have cover:

To determine whether your target has cover from your ranged attack, choose a corner of your square. If any line from this corner to any corner of the target’s square passes through a square or border that blocks line of effect or provides cover, or through a square occupied by a creature, the target has cover (+4 to AC). — d20 SRD, "Cover"