Phobos-developers
[Phobos Bug] Trajectory=Straight sudden projectile slowdows
Description
No clue if it's something the engine does and we're unaware of it, or is it a bug with Trajectory=Straight implementation, but i noticed that such projectiles might randomly stop for a very brief moment at any point during their flight, slightly delaying their impact (at least it looks that it is delayed?). I never saw anything like this happen with Arcing=yes projectiles, though.
Phobos Version
https://github.com/Phobos-developers/Phobos/commit/f51baf98a0c28e8777d7010246c30a52cc45f699 (the newest build i tested with, first noticed it with some older non-dev branches)
Expected behaviour
Consistent projectile movement speed,
Actual behaviour
Watch the projectile fired by the Abrams in the middle, a bit over halfway through (Trajectory.Speed= is the same for all visible projectiles).
We're unable to reproduce the issue, what are exact condition that make this happen? Also maybe the slowdowns were fixed in latest develop branch builds?
It doesn't happen every shot. It's completely random, can vary between each attack (sometimes one projectile gets slowed down, then next time it might be another one, or none at all), and it's more noticeable the longer the range becomes (weapons used here all had something around 10-12 range). It happens even if units use the exact same weapons, so it can't be difference in stats.
Newest dev build doesn't change anything, it still happens there.
It doesn't happen every shot. It's completely random, can vary between each attack (sometimes one projectile gets slowed down, then next time it might be another one, or none at all), and it's more noticeable the longer the range becomes (weapons used here all had something around 10-12 range). It happens even if units use the exact same weapons, so it can't be difference in stats.
Newest dev build doesn't change anything, it still happens there.
I would like further information to help narrow down the potential cause. Any and all related weapon INI code as well as what type of image the projectile use would be helpful. I have not been able to reproduce the issue as shown here (projectile stops moving for a single frame) myself.
[120mmCannon] Damage=120 ROF=90 Range=18 MinimumRange=2 Projectile=Shell Speed=100 Warhead=APFSDS
Trajectory.Speed=150
[Shell] Image=SHLLNORM Shadow=no
SubjectToCliffs=yes SubjectToElevation=yes SubjectToWalls=yes SubjectToBuildings=yes
Trajectory=Straight Trajectory.DetonationDistance=.75 Trajectory.Straight.SnapOnTarget=yes Trajectory.Straight.SnapThreshold=.75 Trajectory.Straight.PassThrough=no Interceptable=yes Strength=50 Armor=ap_tnks
[SHLLNORM] Voxel=yes
UseLineTrail=yes LineTrailColor=16,16,16 LineTrailColorDecrement=64
Also, to demonstrate the randomness, here's an animation from one of the newest dev builds. Ingame speed was 30 frames (no fluctuations). All tanks use the exact same weapon, listed above (duh, 4 of them are the exact same tank).
On 1st volley A3 tank's projectile suddenly slows down. On 2nd volley it's tank B (but it can be hard to spot). On 3rd volley it's A4. On 14th it's A1. On some volleys it does not seem to happen at all.
You can also see that, despite using waypoints to make them fire at once, the tanks do not fire at the exact same time, and they desynchronizes the longer they keep firing (the engine adding a random value to unit's ROF after each attack?).
As pointed out by @Starkku on Discord, the RoF fluctuation is actually vanilla behavior, it fluctuates by 1-2 frames by design, so you're right it changes a bit.
The ROF thing was just an observation. And if it bothers you, feel free to remove the "phobos bug" label. I added it only because i didn't see this issue for anything but Trajectory=Straight, but i personally doubt that it has anything to do with Phobos. Most likely it's some kind of position adjusting that's done behind the scenes to all projectiles, but normally unnoticeable because the projectiles couldn't fly straight until now.