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Turning Rigid Body/Kactors on and off and appling force

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    Turning Rigid Body/Kactors on and off and appling force

    Hello Forum,

    This might (hopefully) be a really easy question but I haven't been able to find a solution on the forums yet but hopefully someone out there can help.

    I have a grate on the floor that I'd like the player to be able to walk over initially, but after certain events the grate should be blown off. I'd imagined that I could just place a Rigid Body actor, have it asleep and then trigger it to wake up and apply a force to it, but this seems trickier than one would expect.

    1) I can't get the Rigid Body actor to start in a "sleep" state, when you walk on/off it, it always reacts to the player. I've tried setting the Physics property under the properties->movement tab to PHYS_None, but this doesn't work. Any help?

    2) I can't find a way to apply a force to a Rigid Body actor via Kismet. There isn't an "activate" event or action for the forces or impulses under the RigidBodyBase Actor class.

    I can think of a few ways round this issue using matinee and animated objects, but that would take a lot more work to get it looking right and I have yet to venture into UnrealScript. Any help would be great.



    Well I look at it like this, since any static mesh can be come dynamic.


    A cool way of interacting with physics objects in terms of force would be the projectile class:

    1) Force Control
    2) Particles Attached
    3) Works

    You can use the provided types some are perfect or create a copy and modify it to not have particles and only force.

    You can control the direction of the projectile via the Editor by placing notes and the position create a vector so you can aim it any way you want.


    And real easy to apply to triger events ect.. via Kismet:


    And just for proof of concept a video (80mb): lol I had Grate Fun

    Glad to discuss further.


      Thanks for the reply, This has an unfortunate drawback in that the player can shoot the grate and this will also trigger it to become dynamic. I need away to control it so it only becomes dynamic after the triggered event/when I tell it to.

      Where are the projectile classes please? So I can increase the force and change/remove the PFX, as that side of things seems to work fine.

      Thanks for taking the time to investigate the problem with me


        The files are located in Development\Src\UTGame\Classes

        Prefix is = UTProj_

        Ok Epic needs to have a look at how we need to be able to toggle RB on and off, all the system variable are generated at start up run time and if its not set to RB during level startup it wont listen or create any RB models etc...

        With kactors you can Toggle Hide so with two kactors one set to RB and the other set to disable RB you can accomplish the task.


        Workaround but you have to:

        1) Hide the RB Kactor at startup )Prevent Z fighting Annoying
        2) Place both Kactors at same XYZ )not too bad
        3) Toggle Hide unhide before applied projectile force )not too bad

        2hrs and no other way found


          Hi there!
          Inside the properties of the kActor, ib the kActor field, you should find a checkbox named bDamageAppliesImpulse. This is ON by default. If yoo toggle it off, it won't react until you touch it. It doesn't solves all the problem, but i think it will help.



            the swapping out does the job, cheers for the help guys, really appreciate it


              old and maybe dead thread, but have you found a way to only acivate physics when you need to? I have the same problem that a player walking over a kactor somehow activates it..



                class CollapseableKActor extends KActor;

                simulated event PostBeginPlay()


                event Detach( Actor Other )