High cover granted by destructible objects is bugged

[Iridar]

Example

Same bug happens with several Templar Pillars spawned in a row. Example.

X2Effect_Pillar is based on X2Effect_SpawnDestructible, so it stands to reason that cover granted by Pillars works the same way as cover granted by cars, as they are destructible objects as well.

In both cases units can see and shoot through high cover as if it's not even there.

Interestingly, this doesn't happen with several Bulwark SPARKs in a row. Example.

In that case, the soldier steps out from behind the middle SPARK and shoots through one of the side SPARKs.

Speculation on the cause

The problem seems to be tied specifically to how destructible objects grant cover. Perhaps, the problem is that each individual tile occupied by a destructible object is treated as an independent source of cover, which creates a conflict of sorts, potentially somehow associated with the cover peek system.

Speculation on the fix

Since destructibles have their own state objects, which contain the information about what tiles are occupied by the object, it may be feasible to identify potentially bugged cover tiles and fix them somehow.

One such potential fix - however dumb that sounds - is spawning invisible units with the Bulwark-like ability on those tiles, though it wouldn't fix the line of sight.

[Iridar]

Depending on whichever approach is used to fix this bug, the fix may or may not be appropriate for Highlander, but we need a place to track this bug either way.

[Tedster59]

Another example, this time involving a high wall. The officer just shot that unit with a 99% hit chance shot

https://imgur.com/a/1BnqACL

[Iridar]

Well shit what an unfortunate turn of events

[Tedster59]

https://i.imgur.com/CkD7Wnc.jpg - not sure how to describe this one or if it provides any additional clues as to what's happening

[BlackDog86]

I'm struggling a bit to understand what the desired behaviour would look like - is the suggestion that the centre tile of lines of destructible high cover should block LOS in both directions?

It's just that - if for example, you put three street-lights which provide high cover in a row it probably wouldn't seem too unreasonable for a unit to be able to shoot through and/or be shot at through them. Whereas if you're standing behind a completely solid panelled-van, you'd probably expect that to break LOS.

Do we know if the game is clever enough to be able to distinguish between those two things?

[Iridar]

Both the vision and cover systems are entirely native, so we don't have much insight.

[Tedster59]

Right now, I think the game makes 2 fundamental assumptions that cause the issue.

1. If you're not peeking in a direction, you're not taking cover from that direction.
2. If you cannot peek around a tile on either side, you can't be seen (e.g. giant wall).

In the "giant wall" situation, it makes sense, since the only way for a unit to see the "in cover" unit is for the unit to be flanked entirely. this breaks down when you have high cover, that can't be peeked around, but can be seen though. I think the game goes "you can be targeted, you're not peeking in the direction the targeting is coming from, therefore you are flanked."

I see a few workarounds that I have no clue which are even possible.

A. Force peeking behavior for all high cover tiles somehow. Would this involve some new "Peek over" type animation, or maybe use the half cover crouching function? not sure how to implement.
B. Make all high cover tiles that can't be peeked around block vision somehow.

[BlackDog86]

In the first example Iridar posted, is the unit considered flanked by the sectoid, as well as the sectoid being flanked by the unit?

[Tedster59]

Both, but it's about the tile that the unit moves to that the mouse is currently highlighting. That tile flanks the sectoid based on positioning, but the red shield shows that the game things that spot is flanked by the sectoid.

[BlackDog86]

What's really weird is that these destructibles are set in UE3 to block unit visibility already - This is the destructible archetype for the pillar:

[BlackDog86]

Using X2DebugVisibilitySelected with trooper selected & cursor on unit on bugged tile:

Yields the following output:

[1025.24] ScriptLog: Visibility info from 870 to 30
[1025.24] ScriptLog: bClearLOS             : True
[1025.24] ScriptLog: bVisibleBasic         : True
[1025.24] ScriptLog: bVisibleFromDefault   : True
[1025.24] ScriptLog: bVisibleGameplay      : True
[1025.24] ScriptLog: CoverDirection        : -1
[1025.24] ScriptLog: PeekSide              : eNoPeek
[1025.24] ScriptLog: PeekToTargetDist      : 147456.0000
[1025.24] ScriptLog: TargetCover           : CT_None

Move the unit to the 'non-bugged' tile and you get this:

[1124.19] ScriptLog: Visibility info from 870 to 30
[1124.19] ScriptLog: bClearLOS             : True
[1124.19] ScriptLog: bVisibleBasic         : True
[1124.19] ScriptLog: bVisibleFromDefault   : True
[1124.19] ScriptLog: bVisibleGameplay      : True
[1124.20] ScriptLog: CoverDirection        : -1
[1124.20] ScriptLog: PeekSide              : eNoPeek
[1124.20] ScriptLog: PeekToTargetDist      : 156672.0000
[1124.20] ScriptLog: TargetCover           : CT_Standing

Notice that the TargetCover from GameRulesCache_VisibilityInfo is CT_None for the active tile. While determining if a unit is flanked or not, the following code runs (getFlankersOfTarget in X2TacticalVisibilityHelpers)

if( (bInvertTeam == bIsEnemyTeam) && UnitState.CanFlank(bAllowMeleeFlankers) && UnitState.GetMyTemplate().CanFlankUnits )
			{
				VisibilityMgr.GetVisibilityInfo(UnitState.ObjectID, TargetStateObjectID, OutVisibilityInfo, StartAtHistoryIndex);
				if( OutVisibilityInfo.TargetCover != CT_None )
				{
					OutFlankingEnemies.Remove(Index, 1);
				}
			}
			else
			{
				OutFlankingEnemies.Remove(Index, 1);
			}

If the unit has cover to the enemy, the enemy is removed from the OutFlankingEnemies array, leaving only the flanking units in it. Since the destructible actor is not considered to be granting cover at all, it skips the check and the unit is considered flanked by the enemy.

[BlackDog86]

Spark cover is granted by a different mechanism (X2Effect_GenerateCover) which seems to work correctly (despite the persistent effect using CoverEffect.CoverType = CoverForce_High; to force high cover on the unit. We could probably find out the peek direction in that situation as well but I don't think it really matters in the end. What matters is that the unit has LOS and cover is granted properly by the X2Effect_GenerateCover, in a way that isn't the case with the destructible archetypes.

What's very weird, is that the templar pillar destructible archetype has the CoverForce_High flag set on it in the UE3 editor and yet still the cover isn't granted.

[BlackDog86]

Whatever this vehicle is, it blocks LOS completely so the problem doesn't happen. Perhaps we can check the differences in the configuration of this vehicle's destructible archetype and objects which aren't blocking LOS. We could then make changes to some of the affected destructables so they essentially aren't treated as transparent & able to be shot through?

[BlackDog86]

For reference, the vehicle with the cover issue in Iridar's first example is ARC_SalvagedSUV_A and the one in the above picture is ARC_RustedSUV_B. Differences between the two archetypes are:
Ignore Supporting Floors (On for Salvaged SUV, Off for Rusted)
Hideable While Blocking Object of Interest (Off for Salvaged SUV, On for Rusted)
Cover Force Flag (High for Salvaged SUV, Default for Rusted)

Everything else is identical. Perhaps it's a problem with the cover force flag on the archetype. Pillar uses Cover Force_High as well.