Bug with CLEAR_FOG and UNCLEAR_FOG macros

[blob]

I recently played with the CLEAR_FOG macro as defined in interface-utils.cfg, and found that using it multiple times in a row does not work the way one would expect.

The first CLEAR_FOG always works fine. It creates an invisible Fog Clearer unit with no interface icons on the map.

Each additional CLEAR_FOG, however, while it still creates an invisible unit, creates some interface glutter (see screenshot).

To find out why, I inspected the macros and found that the CLEAR_FOG macro gives a unique ID to each Fog Clearer. The reason is that the Fog Clearer, while invisible on its own, creates the aforementioned interface glutter, so it is hidden via a [hide_unit] tag. Given that the [hide_unit] tag only takes x- and y-coordinates, and given that there is no guarantee that the Fog Clearer (being a reguler unit itself) is actually placed on the user-specified coordinates, working with unique IDs seems about the right way to solve this issue.

Either way, the ID (a variable called fog_clearer_i) starts with 1 if no Fog Clearer yet exists, but is supposed to be incremented by 1 if already defined. This, however, cannot work as the ID is cleared again when the macro finishes. Here the relevant code snippet:

Code: Select all

    # Here the ID is either created or incremented:
    [if]
        [have_unit]
            type=Fog Clearer
        [/have_unit]
        [then]
            [set_variable]
                name=fog_clearer_i
                add=1
            [/set_variable]
        [/then]
        [else]
            [set_variable]
                name=fog_clearer_i
                value=1
            [/set_variable]
        [/else]
    [/if]
    # Here the ID is cleared again - makes no sense:
    [clear_variable]
        name=fog_clearer_i
    [/clear_variable]

The macro would work the expected way if that last piece of code that clears the ID was removed. The reason is that [hide_unit] will always hide the first Fog Clearer because the units are given identical IDs.

Incidentally, the code for UNCLEAR_FOG does not clear the ID, even though it really should.

To sum up, the correct code for CLEAR_FOG and UNCLEAR_FOG should be:

Code: Select all

#define CLEAR_FOG SIDE X Y RADIUS
    # Clears fog in a specific area for the given side. This is to be used only
    # for the duration of an event: always use {UNCLEAR_FOG} (below) before the
    # event exits, or otherwise you'll be left with fake fog clearer units on
    # the map.
    [if]
        [have_unit]
            type=Fog Clearer
        [/have_unit]
        [then]
            [set_variable]
                name=fog_clearer_i
                add=1
            [/set_variable]
        [/then]
        [else]
            [set_variable]
                name=fog_clearer_i
                value=1
            [/set_variable]
        [/else]
    [/if]
    [unit]
        side={SIDE}
        type=Fog Clearer
        id=fog_clearer_$fog_clearer_i
        x,y={X},{Y}
        max_moves={RADIUS}
    [/unit]
    [store_unit]
        [filter]
            id=fog_clearer_$fog_clearer_i
        [/filter]
        kill=no
        variable=new_fog_clearer
    [/store_unit]
    [hide_unit]
        x,y=$new_fog_clearer.x,$new_fog_clearer.y
    [/hide_unit]
    [redraw]
        side={SIDE}
    [/redraw]
    [clear_variable]
        name=new_fog_clearer
    [/clear_variable]
#enddef

#define UNCLEAR_FOG
    # Restores fog that was temporarily cleared (check CLEAR_FOG above). Only
    # one UNCLEAR_FOG is required no matter how many times CLEAR_FOG was used.
    [kill]
        type=Fog Clearer
        animate=no
        fire_event=no
    [/kill]
    [clear_variable]
        name=fog_clearer_i
    [/clear_variable]
#enddef

Operating System: Windows XP
Version of Wesnoth: 1.8.3 (English)

[boru]

Yeah, I was grappling with this on Sunday. Documented here: http://www.wesnoth.org/forum/viewtopic.php?f=21&t=31004

[zookeeper]

I've always quite hated how hacky that macro is, but unfortunately we still don't have a better way of clearing fog...I'll fix the bug and try to clean it up a bit more.

[Iris]

Unfortunately, [hide_unit] doesn't support more than one target, selected by a (x, y) specification (not even a complete StandardUnitFilter). Hence you get visible fog clearers if you have a hidden unit already, which is the case when the first fog clearer is created.

Patches welcome!

[zookeeper]

silene fixed [hide_unit] and [unhide_unit] to accept a SUF in trunk already, and the macro has been accordingly simplified. The fix suggested here by blob and in another thread has been applied to 1.8.