Simulation Issue


I have a blueprint that has a few objects in it that has physics simulated. When I use simulate they fall to the ground as expected, but when I change any exposed variables within the blueprint it resets back to where it started prior to the simulation starting.
This used to work as I have done it many times in the past, but I don’t think I have done it since using 4.10.
Can anyone confirm if this is working in the latest 4.11 build?


Hello Tocs,

I have a few questions for you that will help narrow down what issue it is that you are experiencing.

Quick questions:

  1. Can you reproduce this issue in clean project?
  2. If so, could you provide a detailed list of steps to reproduce this issue on our end?
  3. Could you provide screen shots of any blueprints that may be involved with this issue?

Hi Rudy,

I just created a new blank blueprint project in 4.10.4 with starter content (so I had something to enable physics on).

I then created a new actor blueprint and set it up as per below.

Note that I created a boolean that does nothing other than makes this issue appear (it works for any updated variable).

I place this blueprint in the world and lift it up a bit and hit simulate. The objects fall to the surface.
When I then select the blueprint while simulate is running and toggle the boolean the physics objects jump back up to a peculiar position.
The issue also appears if any of the rendering, input or actor fields are changed.

Also further playing around with it I have noticed if the blueprint is located over the map origin then when it is refreshed the objects move directly up.
But if the blueprint is say at 400,0,200 when the objects are refreshed the objects move up but also move twice the distance away from the origin of the map, so in this example they move to 800,0,200. Or if it was 400,400,200 then they move to 800,800,200, etc.
Its hard to measure but it looks like the Z value is slightly increased also but definitely not double.

I hope this helps.

Hello Tocs,

I was able to reproduce this issue on our end. I have written up a report (UE-28457) and I have submitted it to the developers for further consideration. I will provide updates with any pertinent information as it becomes available. Thank you for your time and information.

Make it a great day