Player movement not smooth on mobile

Hello, i’ve discovered what i think it’s a bug or at the very least it’s something very annoying. I was following the endless runner tutorial on youtube and decided to implement it exactly like it is but as a side scroller so the player can only move endlessly on the Y axis. However what i’ve noticed is that if you play on mobile (HDR or not) the movement is not smooth, sometimes it kinda like jumps somehow comparable to like if the framerate suddenly dropped but it’s not fps problems as my fps are always locked on 30 or 60.
I followed several steps to test different stuff and it was always the same on mobile:

  • Created own project twice (BP and C++) and moved a mesh every tick multiplying deltaSeconds by a movement vector.
  • Created the side scroller template and added movement input on every tick, multiplying deltaSeconds by a scale factor
  • Created the flying template, rotated the camera so it was sideways and when you thrust and you reach the maximum speed you start to notice these jumps.

I can’t show any captures or videos but this is easily reproducible. I reinstalled the engine completely and tried both BP and C++ for every test. I also tried running the game on the editor (which ran fine), running the game on mobile preview (ran with the problems i said) and ran the game on a physical device (Android - Also ran with the problems).

I don’t really know if this is a expected behaviour due to framerate or something but i’d hoped that by multiplying by deltaSeconds i’d get framerate independent movement. if this is not a bug and i have to compensate for longer or shorter frames, how can i do it.?

Hi DylanVelezDev,

On what device are you testing this? But you’re able to reproduce the issue in mobile preview, you said?

Yes, on mobile preview i’m able to reproduce this. Also on a low end device with adreno 225 (but fps are not a problem as the game runs at 30 fps). The best i can do to describe the problem is like if i want to move from point A to Point B i just have to multiply DeltaTime by velocity and add that to relative location. In editor or standalone it plays smoothly enough, but in mobile it’s like it moved from point A to point A.1 instantly so you can notice the sudden change of location, then from point A.1 to point A.2 and so on until it reaches point B.

Hello DylanVelezDev,

I noticed that you said that your frames were locked when you were testing your project. Did you use the “Use Fixed Frame Rate” to achieve this?

Nope, if i used the fixed frame rate option it would only speed up the fps. I just set the minimum and maximum fps options to the same value.

Hello DylanVelezDev,

I see that you mentioned reproducing this issue in a clean flying template. I tried to reproduce this issue myself and was unable to do so. Could you provide a detailed list of the steps that you used to reproduce this issue within the flying template?

I just created a new test project with the kenney sprite pack and recorded a gif. if you observe the background and not the character you’ll notice something like it’s like it were fps problems but the fps are locked at 30 or 35. The problem might not seem much but after a while following and object with a camera it becomes very annoying.

I thought it might be setup problems but my dxdiag seems to be ok and my pc has a nvidia gtx 650 ti boost with 2Gb GDDR5 but in any case i’ll attach my dxdiag too. [log][2]

As for the steps to reproduce the problem, i do nothing in special. just create a blueprint project from a template (any template) and run in mobile preview or device (with target platforms set to mobile with HDR)

Hello DylanVelezDev,

I am unable to reproduce this issue on our end. I have tried several variations of the the test that you have provided. In order to eliminate any possibility that it could be the pc that you are running the project on could you package out your kenny project in the gif to a supported mobile device and reply with your results? Included in these results I will need the exact device used as well as the exact version of the OS that is being run on the device.

Hi Rudy, I’ve already packaged several test projects to different supported devices and can say that the problem is not there on these devices, so i think my pc’s causing the problems. I did a complete reset a few weeks ago so that might be it, because i still have the problems on mobile preview.

Hello DylanVelezDev,

I have listed the recommended specifications below, you may be experiencing issues because your machine is below the recommended specs.

Recommended specs:

  • Intel Core i7 4930K processor

  • Intel X79 chipset motherboard

  • 32GB RAM

  • 1TB SSD

  • Nvidia GTX 770 video card

You could try turning your scalability settings down. This option can be found under settings > Engine scalability settings

Hello DylanVelezDev,

We have not heard back from you in a few days, so we are marking this post as Resolved by for tracking purposes. I have selected your last comment as the answer for this question as I believe it to be the correct one. If you gather further information that points to this not being the case please feel free to reply to this post and I will be happy to investigate further. Thank you for your time and information.

Make it a great day.