Cover is an opaque object that blocks both line of sight and bullets. Concealment is an opaque object that block line of sight, but not bullets.
AI can fire upon a distant known target that is behind concealment. This is generally desirable when firing on or suppressing a target that is directly behind cover or concealment. Rather than aiming at the unit, the firing unit aims at the concealment.
In some circumstances, AI can fire precisely (it may also be self directed suppressive fire?) on targets through concealment that is between the firing unit and the target (without any line of sight).
This includes when the concealment is directly in front of the firing unit. For example, an AI inside a building can fire upon a target he has never seen, that is a hundred metres away, through a closed wooden door that is 1m in front of the firing unit.
It is completely implausible to blindly aim at an unseen target with enough precision to hit anything that distant (a man at 100m is 1° tall by 0.3° wide).
If the positions are reversed, so the concealment is 2m in front of the target object and the firing unit has clear line of sight to the concealment, the situation is perfectly plausible as the firing unit has a visual object to aim at (just aim at the door, assuming the firing unit knows the enemy is behind it).
For AI to blindly precisely fire on targets in this way, two conditions must be met:
- another member of AI group must have current line of sight with the target
- firing unit must hear the target unit (for example, hearing the target firing an MX rifle from 120m away)
For AI to suppress a target, only the first condition must be met, which means it can occur at much more unreasonable ranges.
AI should require some line of sight with the area/unit they are suppressing. They should not be able to direct fire through nearby opaque objects with precision towards distant targets, as they have no means to aim their weapon without any visual reference with enough precision.
A possible solution could be a partial line of sight test, where AI must have clear line of sight for say 25% of the distance to the target unit/area. This would allow AI to "pray and spray" through foliage etc at nearby targets, but be unable to provide implausibly precise fire though concealment at a distant target unit/area.