Why the box collision don't move with the projectile?


I have a problem with my collision detection for my projectiles.

I have a pawn with a box collision (set to be blocked by the environnement), from this pawn I inherit other pawns with custom projectiles with meshs that i used as projectiles in my project (the collision of theses projectiles’ mesh have been disabled) but theses pawns keep the box collision from the original pawn.

When I shot my projectile, the mesh move properly but the box collision stay here and don’t move at all even if box collision and the mesh are in the same scene root component.

And because the box collision stay here, my projectiles don’t collide on anything :confused:

First, why 2 components in the same scene root could move differently, there are not suposed to be linked by their transform gizmo ?

And how can I fix that my projectiles collide as I want ?

Here, screens on one of my projectiles and a screen in-game (with rendered box collision to show you that they don’t move).

Thanks you for your help.

In the Components tree view, drag and drop the StaticMesh component so that it becomes a child of the BoxCollisionProjectile component.

Thanks for your answer.

I already tried this.

And then : the projectile don’t move at all : it stay with the box collision, the box collision still don’t move.

Any idea ?


Are you sure collision is completely disabled on your StaticMesh? Can you post screenshots of the Blueprint or post the C++ code that handles movement?

This the the staticmesh collision settings :

And the movement is handle by a projectile movement linked to the projectile, here a screen :

I just have a blueprint to spawn this pawn and set its rotation and location.

If you are using ProjectileMovementComponent to move your stuff, then you want to disable physics on your components. ProjectileMovementComponent has its own movement logic that doesn’t use PhysX/rigid body physics to simulate movement. I’m not sure what happens if you try to use it and have physics enabled at the same time.

ho ok, good to know, thanks you.

Indeed without physics, the projectile move properly with its box collision.

but now, the collision is not applied, even if my box collision have the good settings, my projectiles passes through walls and other objects.

here a screen of a wall should block my projectile (my ship is blocked properly) :

and here the box collision settings :

thanks for your help

If you want the projectile to have rigid body physics (bouncing, spinning), you should remove ProjectileMovementComponent and re-enable rigid body physics, and then apply force to the rigid body to make the projectile move.

If you just want the projectile to be destroyed when it hits the wall, leave it the way you have it now, make sure that you have ‘block’ set for both the wall and the projectile, and make sure you have the projectile’s object type set to WorldDynamic (or something like that, but not WorldStatic). Then, you’ll want to use Blueprint to listen for when the projectile collides with something, and then play some explosion effect, destroy the projectile, deal damage to the thing the projectile hit, and whatever else you want to do.

Thanks for theses explanations, the rigid body is the box collision right ?

When I use “Add force” on it, it don’t move at all, this is my blueprint about spawning projectiles :

Thanks you a lot

Try an even higher number, like 10000.

wow yeah indeed it need 1000000 to be interresting.

thanks a lot for your patience and your answers dude.

Hi, I’ve had a similar issue which a night’s sleep has helped me fix. I’m still a beginner so forgive me if this is wrong, but try making the collision component the root of your actor (and delete the scene component). It seems to me that a projectile component reads movement only from the root.