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    Rolling ball jumps on flat surface

    Hello everyone ,

    I'm a beginner with the Unreal Engine 4, so I wanted to create a very simple platform game where the player controls a ball,

    But I have a problem, sometimes the ball jumps even on a flat surface :


    For the collisions I use a box simplified collision :

    Click image for larger version

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    And this is how the collision looks like on the map, as we can se there's no "space" between the boxes :

    Click image for larger version

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    Can someone explain to me why the ball is jumping and how I can fix it?

    Thanks for your time!

    (Sorry for my English, I'm French).
    Last edited by MyroG; 08-03-2015, 12:06 PM.

    #2
    What's the ball collision set to? it seems like it's hitting facets somewhere
    And you've made sure all of your boxes are exactly the same Z height correct? I see the Z is set to 569.9999939 on the selected one, if they're off even by a little you can get a pop pretty easily

    Comment


      #3
      Thanks for your reply

      The ball uses a "Sphere simplified collision", I also enabled "CCD collision" :
      Click image for larger version

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      I changed the Z to 0 for all my boxes, but it doesn't change anything, the ball is still jumping.

      Comment


        #4
        I'm thinking that it is still seeing the edge of the boxes as being the problem, it might be a good thing to try and make a single collision box that encompasses everything in a row, and see if it still bounces. maybe stretch one box to be the whole length and see if the ball still bounces, that should tell you whether it's the spherical collision or the boxes

        Comment


          #5
          Sorry for the double-post, but I wanted to add something.

          I don't know if it may help you, but this time I tried something different.

          I deleted all the blocks and I created a landscape using the "Landscape" tool, I didn't change anything on the landscape:



          As we can see the ball is still jumping, so the problem is maybe the ball, here are the details of the ball:

          Click image for larger version

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          As I said on the previous comment, the ball uses a "Sphere Simplified Collision".

          Best regards,

          Pascal.

          edit : I didn't saw your previous comment Visnarel , I'll try it, thanks

          Comment


            #6
            Hi everyone,

            This is a known issue and has been reported as UE-16238. I am going to update the bug report to show that more developers are affected by this.
            Adam Davis | Marketplace Support | Epic Games
            How to report a bug? | Installation & Setup issues? | Answerhub Bug Reports | Twitter

            Comment


              #7
              Thanks Adam Davis for your reply

              So the only thing I can do is to stretch one box instead of using many boxes (I tested Visnarel method and it works).

              Thank you everyone for your time and have a great day.

              Comment


                #8
                Double post removed
                Last edited by gunnar.kriik; 10-13-2015, 05:16 PM.

                Comment


                  #9
                  Just discovered this issue by accident, and realised that I am experiencing the same issue with a skateboard simulator as well. The wheels of the skateboard are primitive sphere colliders, and as they roll, they seem to catch on the internal edges of the collision mesh(es). See the video below, but it is basically the same issue as what OP is reporting. Physics substepping is enabled. Happens randomly, and speed / angular velocity of the sphere does not seem to matter. Have tried many things, but have not yet been able to make the random "popping" on edges go away.

                  Has there been any updates to issue UE-16238?



                  Thanks!
                  Last edited by gunnar.kriik; 10-13-2015, 05:19 PM.

                  Comment


                    #10
                    In case anyone doesn't know, the option in 4.13:
                    project settings --> physics section --> max contact offset
                    seems to fix this. Set the number lower to prevent the bounces

                    Just replying to this old thread, since i found it from googling the problem, and hopefully this will help anyone else with the same issue

                    Comment


                      #11
                      Originally posted by 11007 View Post
                      In case anyone doesn't know, the option in 4.13:
                      project settings --> physics section --> max contact offset
                      seems to fix this. Set the number lower to prevent the bounces

                      Just replying to this old thread, since i found it from googling the problem, and hopefully this will help anyone else with the same issue
                      This mostly resolved my problem. Thank you very much for taking the time to post here with the solution!
                      I chose a Max Contact Offset of 0.125. Will test that for a while.
                      Contact me: (Steam: Neillithan) (E-mail: neilvmoore@gmail.com)

                      Comment


                        #12
                        Hey I've been working on a rolling ball game as well, and have been running into similar issues. One way I've been able to work around the problem is to create a large cube that encompasses the area and use that as the collision - set the in game visibility to hidden, or make a transparent material to apply to several of these collision boxes. Then for you flooring set their collisions to No Collision. Smooth Ride. I know this is an old thread, just thought I'd share what I've come up with.

                        Comment


                          #13
                          Originally posted by 11007 View Post
                          In case anyone doesn't know, the option in 4.13:
                          project settings --> physics section --> max contact offset
                          seems to fix this. Set the number lower to prevent the bounces

                          Just replying to this old thread, since i found it from googling the problem, and hopefully this will help anyone else with the same issue
                          I love you, because this worked. I also changed Min Contact Offset. Here are my values:

                          - Contact Offset Multiplier = 0.02
                          - Min Contact Offset = 0.01
                          - Max Contact Offset = 0.05

                          I don't know if those values are overkill, but it completely helped with my rolling ball collision behavior. No more erratic bouncing on flat surfaces!

                          Comment


                            #14
                            As of at least 4.21 this no longer works, and the ball will jump when rolling over the seams. I can't seem to get any combination of values to provide the desired results.

                            Comment


                              #15
                              Bump, Chris is correct!

                              Comment

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