Enemies shooting through walls?

[Amon]

Players,

There have been two reviews that have mentioned enemies shooting through walls (I believe the specific creature they are referring to is the Beratzu Summoner which shows up in the first few levels). I am trying to fully understand the behavior observed and determine how to reproduce this behavior. Can anyone describe and preferably show a screenshot of a situation where this happens? I am not sure if the players were assuming the creature shot through a wall simply because the attack cam from a dark area that they couldn’t see, or if they are referring to an attack that clips a corner or passes through a gate (these are allowed by design), or if they actually saw an attack coming directly through a solid wall (that should not happen).

Please describe in as much detail as possible, preferably with screen shots, if you have encountered this problem.

Thanks for playing!
Amon

[Honk]

I think I have seen what those guys were reporting. Let‘s assume there is a quadratic room, 8×8 or similar. There is one opening (let‘s say digged in) in the north mid and directly below a created wall. And left of That created wall Another created wall. If you stand in the mentioned opening, you cannot see monsters directly south in the room, because the wall below and left below allows only sight to south east. But the monsters still Hit you and the animation looks like the attack goes straight through the wall below.

• This reply was modified 4 years, 8 months ago by Honk. Reason: Clarified place of opening

[Amon]

I see, it is because the animation goes to the center of your square, but an attacker can hit a target even if they can only see the corner of the target’s square. The rules of line of sight do not always guarantee that someone who sees a target can also be seen by that target.

Thanks for playing!
Amon

[Terrytigre]

I have found the opposite, as player you can shoot through solid walls. It happened in a huge red room. It seems the red walls do not block line of sight if a gate is on the other side. The squares behind the gate can be seen and targeted. I have made a screenshot, and will try to post it…

• This reply was modified 4 years, 5 months ago by Terrytigre.

[Terrytigre]

[Amon]

I can’t see the images, but from your description that works as intended. Closed gates, unlike doors, do not block line of sight or line of effect, they just prevent creatures from moving through them (unless they are incorporeal). I suspect what is causing the appearance of passing through walls is if a line of sight/effect exists from one part of a square to another part of a square, it can be considered to have line of sight/effect, but when firing the power, the animation travels from the center of one square to the center of the other square, which sometimes involves clipping some corners.
If you can re-post the links to those images or give me access to the google drive file, I would like to see them

Thanks for playing!
Amon

[Terrytigre]

I will try again. This ia a link to the image on my google drive:

https://drive.google.com/file/d/1UfOJ9df2QUwEi1Z6khuWKZmlX44Js7Yx/view?usp=sharing

And perhaps I was not clear enough, so I will try to explain again using old style angband like graphics 😉

x x x x x x W . . . . . .
v v x x x x W . . . . . .
x x v v x x W . . . . . .
w w w w w G W . . . . . .
w w w w w x W . . . . . .
w w w w w x W W . . . . .
x x x x w x x W . . . . .
x x x x w w x W . . . . . @

legenda:
W red wall
w grey wall
@ character
. floor
x also floor, as I used . the graphics got shifted
v area that was visible.
G gate.

Note that the Red Wall is solid from top to bottom, so it should block line of sight.
I did some further research after taking the picture, and if you get closer to the red wall the visible area disappears.
Also it occurred even when there was no gate between, so the gate is just coincidental.
My guess would be rounding errors in the line of sight routine, where the wall above and below are both just missed.

• This reply was modified 4 years, 5 months ago by Terrytigre.
• This reply was modified 4 years, 5 months ago by Terrytigre.

[Amon]

Terrytigre,

Thank you! The Angband style diagram works great to demonstrate the issue, however I was also able to see the image on google drive this time and this is definitely a bug in the line of sight algorithm. At least now I have a concrete example to use as a starting point for solving this.

Thanks for playing!
Amon

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