Line of sight is blocked when not expected

[krakun]

This is in 3.2.17, the area is just south of the Forgotten waystation (so just after Vince/KJ burns the bridge).
My understanding of line of sight shooting is that a line is drawn from the middle of the square of the attacker, to the middle of the square of the defender. No tiles intersected by that line should be obstructed. I would think that if a hero can walk on that tile, it's considered unobstructed.




Since I had a doubt with the line intersecting a crosspoint for 4 tiles, I retreated one square with Kyera. In the second screenshot I would think that the ray of holy smitheriting goes through Kyera, Vincent, the tile just to the west of Vincent, Selen, and into the ratkin's ugly snotnose. This seems not to be the case (Vraes just punched the ratkin in the nose, the ratkin then had a broken finger).

[fallen]

krakun - thanks for the screenshots. To get a clear shot, you'd want to step west. The full wall to the north east of the Ratkin is obstructing your clear view.

[krakun]

fallen Thanks. Isn't the rule then "middle of attacker to middle of target?".

[anrdaemon]

Apr 20, 2015 14:02:52 GMT -5 krakun said:

fallen Thanks. Isn't the rule then "middle of attacker to middle of target?".

The rule is it. However, the game engine does not play by the rules :/
You can find more topics on the same issue.

[Cory Trese]

Individual tiles, not pixels, are used to approximate the line of system within the map.

I don't know what anrdaemon means, but fallen has the right advice -- move one tile more and shoot from there.

[krakun]

Ahhh, now I understand.
1) Apply "middle of attacker to middle of target" line
2) The crucial bit: Imagine you are drawing the line with anti-aliasing.
3) Any of those squares that are not 100% free can be considered obstacles. Sometimes you get freebies, like the spike in the middle of the screenshot which is considered walkable.
fallen, @cory Trese, thanks for the amazing and rapid feedback, as always.

[fallen]

krakun - yes, you got it. Crucial bit is to be aware that corners let LoS pass.

[anrdaemon]

Individual tiles? LoS doesn't even TOUCH the tile in question, as it was in my examples. It pass cleanly through transparent tiles only.
You can keep denying the reports and twisting my karma as you wish, it doesn't affect me in any way, I know that bug hunting is a thankless job.

[fallen]

anrdaemon - I am sorry that you feel that way. We try very hard to listen to our community who is reporting bugs and sharing their feedback on the game. I hope we do a good job, because we talk to hundreds of people a week an update the game weekly. We'll keep trying to improve.

You've mentioned before that you think we are "manipulating your karma." Sorry, we aren't.

[Cory Trese]

It all depends on the method of approximation. In this case, Bresenham's.

en.wikipedia.org/wiki/Bresenham%27s_line_algorithm

I don't use the Karma button much, but since you mentioned it I clicked "Exalt" for your taking the time to post the screenshots. Those are nice, and I wish that the code was that simple!

[anrdaemon]

I'll be reading that article when my head cleared enough, but after a quick glance it seems the issue is the same as with any such algorithm, is in actual implementration rather than algorithm description. Namely the incorrectly chosen anchor points, which is not a problem, when you draw pixels (as the pixel is the minimal element you can draw), but tends to be real PITA, when you try to work out LoS with it.
One way to combat the issue (assuming you don't want to change the algo, and I see why you picked it in first place, so that's not really an option) is to use larger tile sizes (3x3 pixels or larger), which would help with correct anchor positioning.
Using 4x4 could even add some gameplay changing terms to the environment. I.e. more correct corners, or actual (rather than artificial) left/right hand distinctions.

[Cory Trese]

Thanks!