What influences projectile impact on physics asset - velo change?

When i shoot with a projectile on a physic actor, how to minimize the impact-influence?

Raising mass on phys actor, lowering mass on projectile and movement speed are giving no satisfying effect.
I need standard hit collision (working), but without applying force or velocity change to the phys actor.


I don’t know if it’s possible to have a collision event without any physics reaction unless your object is more like a static structure - infinite mass. If that’s not an option then you could either change your projectiles to non colliding and use overlap and raytrace to detect if they hit something or get Normal Impulse from collision event and apply reverse of it as AddImpulse. Reverse meaning multiple by -1. This should apply exactly opposite effect to collision reaction.

Thank you very much for your time.
That are many calculations, when projectiles like MG fire is flying around?
Infinite mass is not possible, in my case for Weirddoggy as example.

Weirddoggy follows me everywhere and sometimes when he is hit at the impact location(pic) he starts to overreact a bit (typical flying/spinning).
I shoot projectile with hitregistration, spawn emitter, sound and other subprojectiles, like shotgunstuff.

But projectiles bounce from most surfaces one time minimum and when the subprojectiles are spawned at some specific angle/location, it influences way more, then normal.
I tried some different stuff to smooth the reaction out, temp collision disable, changing spawn offset.

For me it looks like the impact point is the problem, not the spawning stuff with disabled collision.
With that raytracestuff from your post i get many traces, when many stuff is flying around, a bit scared about performance impact.

I am thinking about binding a collisionbox in front of my projectile, set it to overlap and then trigger chainreaction, but that would not help me with bouncy stuff?
When i then cast to specific actors, to prevent bounce on them, they still could get hit by a bounced projectile/subprojectile.
I use that for destructable stuff too and there it works nice.
When i would spawn something like an invisibe counterprojectile and both meeting at real impactpoint, i could use a fresh collisionchannel for that hmm
Then the force would be applied to the counterobject and the real projectile would need no collision to the mainobject.

That’s much stuff only for that problem.
Or reducing velo before impact…
So many stuff to try out.
Regards bauch :slight_smile:

Ohh, I see. As it flies around any collision not aligned with center of mass will try to spin him. Two solutions, one is to try that inverse of Normal Impulse - it’s a vector which you get as a part of collision event. Another option is a PID Controller which can maintain rotation of the flying guy. So it will react to being hit but will rapidly return into a stable/desired state.
I have PID Controller component in MMT, you don’t need a plugin itself to use it, code is very simple. I do something like this to control hovercraft and in PID Controller example to control rotation of the mesh using only torque.

I think even PD controller can do such job, you don’t need Integral part. The general idea is to measure “error” between the current state of your object and what state it should have. For example, in case of rotation, you want character to look at specific direction, so you measure what direction he is looking right now and where he should be looking (his direction will change when it gets hit) the difference between them (angle or vector) is “error”.
PD controller is just this math expression that you need to calculate on every tick:
P * CurrentError + D * (CurrentError - PreviousError)/DeltaTime = C
The result - C is your torque force or angle increment which you later use to correct his rotation. P and D selected manually, simply start with very small P until object can rotate fast enough and then start increasing D until it stops to oscillate.

Oh cool, thank you again.
I use similar stuff, to track down/limit velocity, when throwing objects with physics handle, but it’s hard to trim to get the desired look/feel.
It quick gets the feel of someway “own” gravity system, but for the impact stuff it could be nice!

I tested it before on my inventory, but the problem there was, that i use events for while overlap and they seem to get “nulled” sometimes, while i tried last times.
I made/tested yesterday many different projectiles and some of them are working without errors, but they used no subprojectiles.

The spawned subprojectiles caused problems, because i set collision to “no collision” after spawn, but not in the construction script, of the actor itself!

After adding it to the construction script, some problems where gone, others not.
Now i understand that there seems to be a small millisecond, where the object is spawned with collision and then disabled in event graph.

That small tick of existing collision was a problem too, so far i could understand that weird behavior.
Also it seems to make a difference, if the collision object has a pinpoint at front, or some sort of partial sphere collision.
Dunno how to explain, but i thought pinpoint would give cleaner impact results.
But it seems/feels like a flat impact face (no pinpoint= would be better)?
Here a “pinpointer”, have to try different impact regions.
Another weird thing for me is, that many of my BP actors showing in the CB another asset as integrated in the preview, but it’s not in there.
The Head is a standalone BP actor and i use it often, but it shows in most preview, someway confusing. Ue seems to like that thing and suggest me to use it more often and i obey.^^

Stuff to test for days again but i like that “playdevelopement”.
Sincerely Bauch :slight_smile: