ID:2303458
 
Not a bug
BYOND Version:512.1389 beta
Operating System:Windows 10 Home 64-bit
Web Browser:Chrome 61.0.3163.100
Applies to:Dream Seeker
Status: Not a bug

This is not a bug. It may be an incorrect use of syntax or a limitation in the software. For further discussion on the matter, please consult the BYOND forums.
Descriptive Problem Summary:

Some objects can be seen through opacity.
Using sigma engine for most of the heavy lifting. I'm not sure if anything there would be causing it.

The doors and arches only are visible after crossing them.

The mobs, after moving them? I'm not sure, honestly.



Numbered Steps to Reproduce Problem:



Code Snippet (if applicable) to Reproduce Problem:

obj
dungeon_door
icon='dungeon_door.dmi'
var
open=0
opacity=1
density=1
icon_state="h"
vertical
name="dungeon door"
icon_state="v"
proc
open()
if(!open)
open=1
opacity=0
density=0
icon_state="open"
close()
if(open)
open=0
opacity=1
density=1
icon_state=initial(icon_state)
Cross(atom/movable/a)
open()
return 1

Uncrossed(a)
close()

arch
icon='arch.dmi'
pixel_x=-16
pixel_y=16
layer=10
Crossed(a)
if(ismob(a))
alpha=200

Uncrossed(a)
if(ismob(a))
alpha=255


When does the problem NOT occur?
when doors are left untouched and when mobs remain in their initial location

I don't actually see any bugs at play here.

The core problem is that your arches live on the wrong tile. Set them to TILE_BOUND, and offset them in such a way as their bounding box does not overlap the surrounding tiles.
Okay! The TILE_BOUND bit works for everything. Thanks!
Lummox JR resolved issue (Not a bug)