Units that fire from different locations use the wrong location to check if the projectile is unblocked #3516
A unit such as Thug or Siren that alternately fires from wither gun checks from the last weapon point that fired, then fires from the next weapon point. What this means is the game may fire a projectile even if it's path is obstructed by a friendly unit. Sorry if I don't know what the terminology is in the code.
Video to support. https://www.youtube.com/watch?v=ukTCMtWo3bc
Another case from https://zero-k.info/Battles/Detail/707171
I've done more testing and I now have a list of all the units I could consider.
It seems Rouge and Reaver both are absolutely correct. The cannon it's aiming from is the one that fires. Reaver sometimes can attack ground and hit an alied init head on with it's projectiles, but it seems to work fine. Shogun also seems to be fine, when the front and the back turrets fire, the aimpoints update mid fire-cycle to the next barrel. The middle turret, however, seems to be off by 1 for some reason? it starts it's aimpoint in the 2nd cannon , but it fires 1-2-3 like the others.
Welder and Envoy fire the opposite cannon that they're aiming from, and play the animation for firing from the cannon that it aimed from. This looks a little jarring in game when you pay super close attention, but welder has such a high RoF and Envoy's cannons are so close together that it's fairly unnoticeable that the projectile comes out of the static cannon instead of the animated cannon when playing. These units also rarely friendly fire in a way that you would care too much about.
Hermit, Thug, Minotaur, Ogre, Siren sonic gun, Palidin lightning cannons, and Detriment gauss gunsfire from the cannon opposite the one that's aiming. This means that they can friendly fire allied units and not attack enemies they have a clear shot on. In Detriment's case, it's such a hulking monstrosity I would rather it fire it's gauss guns through allied units no matter the cost just for sheer epic value. Minotaur always fires a 2 round burst, so it matters less.
Also, Fencer, Recluse, Nimbus, Revenant, Hercules, Tremor and Stinger fire from the wrong barrel, but for varying reasons that does not matter. Units like scalpel, firewalker, and duck which fire both barrels in sync are excluded.
I mentioned previously that envoy's firing bug does not mater in the scheme of things. I was wrong.
Here's another battle and video of things going wrong.
I also want to mention that I've seen ogres face-smack my commander and other more minor incidents over the last couple months. Felon also suffers from this bug.