I just started using UE4 and was playing around with the youtube tutorial [Blueprint QuickShot 4 Spawning Physics Actors][1], I modified the approach slightly and used the MaterialSphere from the starter content. Because the sphere was quite large after spawning I modified the blueprint slightly and re-scaled it to reduce the size. Everything worked fine until I reduced the scale below ~0.5 (for each axis), below this factor the sphere suddenly started to drop through the floor. However if I spawn multiple balls within a short period, it suddenly works again. The following [Youtube video][2] shows the problem.
Is this a bug, or do I miss something.
Regards, Tobias
Hey digibert -
I am trying to reproduce this for you, but need a little more information. Could you give me a screenshot of you BouncingBall Blueprint’s component details window? Also, can you let me know if you have set up any custom gamemode or player character information. From your video it doesn’t look like you have, but I don’t want to assume.
Eric Ketchum
Hi Eric,
as you already guessed, I didn’t use any custom gamemode or player character info.
Also I attached a screenshot of the blueprint component details window:
Regards, Tobias
PS. If it would be of any help, I could also try to upload the project to github or some other repository.
Hey Tobias -
So I might have an idea of what is causing the issue based on the screenshots you are showing me. In the components section of your bouncing ball blueprints change the scale back to 1,1,1. Since you are already setting actor scale in your blueprint, the multiple scales could be generating an issue with the physics calculations. See if that doesn’t fix the issue.
Let me know if that works or if you are still having the same problem,
Eric Ketchum
Hi Eric,
Unfortunately this didn’t fix the problem.
I created a git repository with the project, maybe this could be of any help Bitbucket
Regards, Tobias
Hey Tobias -
I was able to successfully reproduce this issue. Thank you for your help. I am passing this along to our engineers, but I want to make sure I give them as much information as possible. On my PC, the issue starts at scaling .10,.10,.10. You had said that your issue started with a scaling of anything below .5. Can you confirm this for me and also give me your CPU specs. (Processor, Memory, Video Card and Video Memory info)?
Thanks Again Tobias -
Eric Ketchum
Hi Eric,
my computer has the following specs:
- 32 GByte of RAM
- Intel Core i7-3840QM CPU (2.8 GHz)
- NVIDIA Quadro K1000M (Feature Level 11_0), with 1926MB of dedicated video memory and 2048MB of shared system memory
Thank you for your support!
Tobias
Hi Eric, I checked again the scale. And everything works fine until 0.5, as soon as I change it to 0.4, the ball starts dropping through the floor.
Tobias
Hi Eric, I found a solution to my problem. If I enable ‘Substepping’ in the Project settings (Physics->Framerate), it works correctly. I guess the problem is due to my low frame rate, which is causing problems during the physics calculation.
Regards, Tobias
Hey Tobias -
I am really glad you found the Substepping and if that works for you great. You may also want to look at enabling Use CCD under Collision in the Bouncing Balls Blueprint components as that corrected the problem for me on my version of the project.
-Eric Ketchum
