[r4019] compat_useblocking doesn't include texture scrollers

[The Green Herring]

The option "All special lines can block <use>" (compat_useblocking) is supposed to "[restore] Doom's original behavior of any special line blocking use actions." However, it appears that ZDoom's definition of a "special line" in this case, unlike doom.exe/doom2.exe's, does not include scrolling texture linedefs.

I have attached a test map with two switches that could be activated from below. To block this, the switch in the west is blocked with the original Doom "scroll texture left" linedef (type 48), with the linedefs facing inward so the scrolling isn't visible; and the switch in the east is blocked via a walkover trigger (in this case, a floor-lowering linedef releasing monsters). If you play this level in doom2.exe, the effect for the western switch works as intended; the player is blocked from activating it until they ascend the stairs. If you play it in ZDoom, however, the player will be able to flip that switch from below whether or not "All special lines can block <use>" is turned on. This is also true regardless of which direction the linedef is facing. This was tested with the pre-built Windows version of the SVN available at http://svn.drdteam.org.

Outside of this test map, at least two levels in Back to Saturn X Episode I (MAP04 and MAP14, specifically) use "scroll texture left" linedefs (made invisible by pointing them inward) to block the player from activating secret switches from below. This works in doom2.exe as intended, but doesn't work in ZDoom regardless of whether compat_useblocking is turned on or not.

[Graf Zahl]

ZDoom clears the special of all scrolling lines, this includes Doom's original 'scroll left' type. So the compatibility option no longer has a special that blocks.

[esselfortium]

So... can it be fixed? It's useful as a feature, and works as intended outside of ZDoom. Alternately, is there some other option I can set to get the same end result in ZDoom without breaking other stuff?

(Since ZDoom already defaults to allowing 'use' actions to pass through line specials, is there actually any benefit to clearing the special from scrollers?)

[randi]

Fixed in r4037.

[esselfortium]

Thanks for that