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:

A . T
. . .

Across a pillar:

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

Between pillars:

. . W . . . T
A . . . W . .
  • \$\begingroup\$ It's an interesting question, but it's also an oddly specific case. I wonder: what prompts this question? \$\endgroup\$ – user8248 Nov 19 '13 at 23:54
  • \$\begingroup\$ 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)? \$\endgroup\$ – Petr Hudeček Nov 20 '13 at 0:01
  • 1
    \$\begingroup\$ 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. \$\endgroup\$ – user8248 Nov 20 '13 at 0:10
  • \$\begingroup\$ 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. \$\endgroup\$ – GMJoe Nov 20 '13 at 4:26
  • \$\begingroup\$ @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. \$\endgroup\$ – 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"

I've made a helpful diagram (code) to detail what's happening:

image description

The red lines detail corners which cross through walls. The blue lines detail corners which are questionable at best. The green lines indicate that there is, indeed, line of sight.

The green line from the bottom right of the attacker's square to the top left of the target's square passes through the gap between the spaces; ergo, there is a line of sight. However, every other pair of lines passes through (red) or next to (blue) one wall; ergo, the target has cover.

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  • \$\begingroup\$ So: Line of sight checks if any point in attacker's tile has a line to at least one point in target's tile. AND, even if lines from all corners of attacker's tile to all corners of defender's tile (as in the last example) are blocked, the target can still be attacked (albeit he has cover). Right? \$\endgroup\$ – Petr Hudeček Nov 19 '13 at 9:20
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    \$\begingroup\$ @Petr If all corners are blocked, the attacker doesn't have line of sight, and can't attack. In your last example, though, there is line of sight. \$\endgroup\$ – user8248 Nov 19 '13 at 14:35
  • \$\begingroup\$ But... all lines from all corners of attacker's square are blocked in the third example. True, some only touch the walls, but that is sufficient, right? Just as touching a corner is sufficient to be blocked. \$\endgroup\$ – Petr Hudeček Nov 19 '13 at 18:56
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    \$\begingroup\$ @Petr Not true; please check again. The line from the bottom right of the attacker's square to the top left of the target's square passes through the middle of the two walls. There is empty space there. \$\endgroup\$ – user8248 Nov 19 '13 at 20:08
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    \$\begingroup\$ @Technically, I think the second case could also bestow line of sight, as the pillars described in DMG usually do not ocuppy the whole square. \$\endgroup\$ – kravaros Nov 20 '13 at 0:03

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