Consistent frontal rear armor hits - The why and how

Ever wanted to consistently score those juicy rear armor hits but flanking isn't really your thing? Well, don't fret because I'll show you a slightly unorthodox (and arguably rather situational) way to do just that - right through the front door... uhmm… armor!
“Impossible?!” you say? Let’s find out how it works.


While playing around with hit boxes and how these interact with scatter values the other day, I stumbled upon a peculiar entry in the attribute editor, "distance_scatter_obj_hit_min", that left me scratching my head about what it actually does.

As it turns out (from the editor description anyways) this defines how far a projectile travels without collision detection, or to put it another way, how far it will actually phase through any objects it would otherwise collide with. These objects include your run-of-the-mill shotblockers, such as tank wrecks or those little tractors scattered around Faymonville, but also other things projectiles are usually meant to collide with – like the nearly impenetrable frontal armor plate of a King Tiger!

However, what goes inside a tank, must also come back out somehow, and if the projectile happens just to be able to phase through the front of the tank before travelling the distance set in distance_scatter_obj_hit_min, the next thing it will collide with is the rear armor of the tank! That is, of course, if you manage to set it up correctly. The following pictures explain how to do just that:

• Step 1: Place your tank within the right distance to the target. Not too far away, since you want the fired projectile to be able to phase through the front armor (blue line) and into the tank before the collision immunity runs out. But not too close either, as otherwise the projectile is going straight through the whole tank without colliding with the rear armor section (red line).
  Show Spoiler
  
  The collision immunity range is 10 m for the vast majority of the game’s arsenal (dashed red arrow), but there are a few exceptions where this distance is 5 m (namely the SU-76, T-34/76, KV-1 and Churchill tanks). As a rule of thumb, try to stay within about a tank’s length (half of that with the tanks mentioned before) to your target and you’re good to go.
  
  
• Step 2: Attack ground behind the tank so that the projectile’s flight path intersects with some part of the rear armor of your target. Generally, the farther the better, but make sure to aim at least far enough so that the entire scatter cone (white trapezoid) lies outside of the target’s hit box. The minimum distance depends on the actual scatter values for each tank gun, but again you’re on the safe side if you attack ground at least 1.5 tank lengths behind the target.
  
  
• Step 3: Profit!
  

Pulling this off in-game is arguably not always easy, but can be very satisfying if you can make it work. And as an added bonus, you can also make use of the collision immunity in a defensive setup.
For example, hiding behind a shotblocker as in the picture below will allow your scatter shots to still hit the target, while your opponent's will hit the wrecks instead (statter shots only, of course).

interesting

This is cheesing the game engine on a whole new level.

I only had time for a quick read so I might have missed it:
Why is it important to ground attack? Do normal "accuracy" shots behave differently? I know they often ignore world objects, but to they always impact on the frontal armor then?

Also, do you have any idea why it exists? Would Coh2 really be THAT buggy if shots didn't phase through for a couple of meters. If so, why is it shorter for only a hand full of units?
Or is this just a weird remnant of a CoH developer entering a random value because he forgot that the SOP said "10"...

I noticed some weird shit like this a few months ago when OST would pop smoke and I would frantically attack ground. I think it works better with turreted tanks since I have never seen it with SU85.

This is cheesing the game engine on a whole new level.

I only had time for a quick read so I might have missed it:
Why is it important to ground attack? Do normal "accuracy" shots behave differently? I know they often ignore world objects, but to they always impact on the frontal armor then?

Also, do you have any idea why it exists? Would Coh2 really be THAT buggy if shots didn't phase through for a couple of meters. If so, why is it shorter for only a hand full of units?
Or is this just a weird remnant of a CoH developer entering a random value because he forgot that the SOP said "10"...

Yeah the normal accuracy hits seem to always hit the front part if the targeted tank faces even just a bit forward (i.e between +89 and -89°) and vice versa for rear armor shots. Not sure what would happen if you hit exactly 90° side-on though, that would probably be worth to test. Also, for scatter shots to show this weird behavior you have to always fire at least some distance behind the target. The exact extent you need to overshoot seems to correlate with the distance scatter of the weapon; if some part of the scatter cone lies inside the hitbox of the target the whole thing doesn't work and you get a frontal hit instead (and not only sometimes, like if a shot would scatter too short to make it out of the tank's hitbox, but apparently it never at all). Hence why, even if you somehow managed to fail the accuracy roll of a regular attack at point blank, the scatter shot wouldn't phase through the front border of the hitbox.

That makes me think this is indeed some buggy and unintended interaction, and I've got no idea why it is even in the game. Maybe a remnant of some obscure bugfix in the very early days of CoH2's development that never got deleted? Hard to say for sure.

The editor description states that "distance_scatter_obj_hit_min" cannot exceed 10 m, yet for practically all weapons this is set to 10 by default. So whatever purpose it might have originally had to tweak this value, it seems pretty much redundant now.

Then again, it opens the door for shenanigans such as this, so there is certainly a purpose nonetheless

I noticed some weird shit like this a few months ago when OST would pop smoke and I would frantically attack ground. I think it works better with turreted tanks since I have never seen it with SU85.

I haven't tested the SU-85 specifically, but it seems to work just fine with any tank I tested. In fact, I wouldn't be surprised if you could actually pull this of with hand-held AT as well...

The minim scatter range might be used so that the vehicles does cause early explosion that can hit the vehicle itself.

I am under the impression that ISU-152 has minimum range of 5 for the exact same reason.

Yeah, this might very well be the reason. It still wouldn't explain why it is 10 m for virually every unit bar 4 exceptions, though. Guess this one will remain a mystery unless anyone involved in the development process spills the beans...

Yeah, this might very well be the reason. It still wouldn't explain why it is 10 m for virually every unit bar 4 exceptions, though. Guess this one will remain a mystery unless anyone involved in the development process spills the beans...

Some stats are simply oversight...

Stuka rocket penetration of 0
FF mid range of 45
Sniper HP 82
HVAP deflection damage
ISU-152 skill deflection damage
KV-2 minimum range
Churchill's acceleration/rotation
PzIV J XP and rear armor values

Yeah the normal accuracy hits seem to always hit the front part if the targeted tank faces even just a bit forward (i.e between +89 and -89°) and vice versa for rear armor shots. Not sure what would happen if you hit exactly 90° side-on though, that would probably be worth to test. Also, for scatter shots to show this weird behavior you have to always fire at least some distance behind the target. The exact extent you need to overshoot seems to correlate with the distance scatter of the weapon; if some part of the scatter cone lies inside the hitbox of the target the whole thing doesn't work and you get a frontal hit instead (and not only sometimes, like if a shot would scatter too short to make it out of the tank's hitbox, but apparently it never at all). Hence why, even if you somehow managed to fail the accuracy roll of a regular attack at point blank, the scatter shot wouldn't phase through the front border of the hitbox.

That makes me think this is indeed some buggy and unintended interaction, and I've got no idea why it is even in the game. Maybe a remnant of some obscure bugfix in the very early days of CoH2's development that never got deleted? Hard to say for sure.

The editor description states that "distance_scatter_obj_hit_min" cannot exceed 10 m, yet for practically all weapons this is set to 10 by default. So whatever purpose it might have originally had to tweak this value, it seems pretty much redundant now.

Then again, it opens the door for shenanigans such as this, so there is certainly a purpose nonetheless

To be honest I believe this might have just been a quick and dirty fix for collision detection problems. Maybe even for an early, buggier version of the engine, but maybe it is still kind of "necessary". I don't know how large Relic was at the time, but there were probably multiple developers fiddling with the system at the same time. Might very well be that one "fixed" some issues with this one, then it got forgotten and/or no one tested if it could be safely removed.
As Vipper suggested, it might also prohibit vehicles from damaging themselves, although this could be set with other parameters. I also don't fully know where the projectiles spawn. If they spawn within the vehicle's hitbox, it might be to prevent instant detonation. Might still have been for an earlier engine version though, since shots phase through friendly tanks anyway now.

Just like you, I also noticed that a tiny angle change from 89° to 91° will fully decide about frontal and rear armor hits. Accuracy hits seem to always travel in a straight line, but I have only tested for stationary targets. Not sure what happens if the target moves. Weirdly, this might lead to tanks with high frontal armor, large target size and large hit boxes like the e.g. Elefant, IS2 and KT to perform better against ATGs, because shots will always hit, and thereby always hit the front armor, even if you attack from an angle. Technically, a low accuracy unit with very low scatter would perform better, since it has the chance to scatter hit the rear.

Anyway, that's a very nice find you got there, albeit an odd one.

Some stats are simply oversight...

Stuka rocket penetration of 0
FF mid range of 45
Sniper HP 82
HVAP deflection damage
ISU-152 skill deflection damage
KV-2 minimum range
Churchill's acceleration/rotation
PzIV J XP and rear armor values

Stuka penetration has been fixed a couple of patches ago.

I won't debate these to not go off topic. But these stats are slightly different. Most of these are directly visible and directly impact the performance of a unit in an obvious, visual, sometimes even quantifiable way.
This minimum distance that MMX was talking about looks more like some odd fix to something the engine could not handle properly, or that Relic did not figure out to handle otherwise.

But I agree that, if there are even "obvious" stats that got forgotten, it is likely that "hidden" stats got forgotten even more often.

It’s probably from when they added rear armor. My guess is the game treats the tank as two separate entities which is why they could never add side armor.

Yeah, chances are it is just a forgotten oddity from earlier development stages. Sometimes the editor reads like a DNA profile with loads of obsolete blueprints still left in its database...

Anyway, I guess the focus wasn't really so much on why this stat exists in the first place, but rather how easy it is to make good use of it. And especially vs big and heavily-armored targets that tend to have a much higher frontal to rear armor ratio and are easy to hit due to their huge hitboxes this can really make a difference. After all, you're in a low-risk, high-reward scenario if you attack ground behind the target when at close range - the chances to miss completely are abysmally small and, in the worst case, instead of getting a rear armor hit you'd roll a frontal armor hit, which you would have done anyways if attacking normally.