I found out today that the ProjectileMovement physics we can add to our blueprints have an effect that are dependent on the framerate;
On low end computers object falls very close while on high end the projectiles fly very far.
Definitely not what you want for projectiles. (visible for example with x velocity of 2500)
I really like that component and obviousely its really convenient but its not usable for most situations because of that.
Is there a solution to this problem?
We digged into it further and found out that our projectiles initial location direction was wrong.
The reason why the physics where so framerate dependent is tricky;
Our projectiles are shot from canons;
The projectile start position initial transform rotation was wrong by 90 degrees. As a result the projectile bounced inside the canon but somehow managed to shoot out straight out of the barrel making us think everything was fine…
We rotated the transform and now the projectiles paths look similar on both low and high end computers.
Basically this confirms that physics are fine for projectiles, but don’t rely on bounces. This said if you need to make something bounce just a couple of times I suppose it should be fine.
I’m still having this problem in 4.8.3. I spawn an actor with a projectile movement component, and it moves some distance at 60 FPS, and only a fraction of that distance at 10 FPS (instead of moving further each frame to compensate).
Very frustrating for network games, as the server’s framerate determines the projectile movement speed of all clients.