I have a cube, a plane and a ball.

At first, I set the rigid body physics of the cube and the plane to passive and the ball to active. I set the strength of the force field physics of the cube to 0 at frame 1 and at frame 50, when the ball falls on the plane, I set it to -100. As expected, the ball falls on the plane and the cube attracts it.

But, after that I use the loop cut tool to cut the faces into multiple faces.

I add the Build modifier and set its start frame at 1 and length to 50.

But now, the ball doesn't hit the cube, but rather goes through it and falls into the bottom. Why does that happen?

  • $\begingroup$ how to set the strength of the force field physics of the cube? what settings are you editing? $\endgroup$
    – Sanbaldo
    Jun 6, 2020 at 12:22
  • $\begingroup$ I recreated your scene (without the force field) and everything is working. the ball impacts the cube even if it's not 100% yet visible. $\endgroup$
    – Sanbaldo
    Jun 6, 2020 at 12:25
  • $\begingroup$ are you applying the "build modifier"? it's not clear $\endgroup$
    – Sanbaldo
    Jun 6, 2020 at 12:26
  • $\begingroup$ @Sanbaldo Yes, I used the "Build" modifier. I also tried without the modifier like you, and you were right, the ball impacts the cube. But how do I make that happen after the modifier has finished building the cube? If you want, I can give you the blend file. $\endgroup$ Jun 7, 2020 at 10:59
  • $\begingroup$ pls share the blend file so we can check it (it's not clear what you are trying to achieve) $\endgroup$
    – Sanbaldo
    Jun 7, 2020 at 11:07

1 Answer 1


I suggest to add an invisible wall to bypass the problem of the cube physics when the build modifier is attached to it. So the ball will collide and bounce on that wall.

This is a quick experiment where the cube acts the way you need (I don't know why it works):


  • $\begingroup$ Thanks bro, I clearly forgot about using the invisible wall. $\endgroup$ Jun 9, 2020 at 10:50
  • 1
    $\begingroup$ If this answer solved your issue, please learn how to accept it. How this site works: blender.stackexchange.com/tour @AmanatAzizKhan $\endgroup$
    – brockmann
    Jun 9, 2020 at 11:53
  • $\begingroup$ @brockmann Thanks, I am new so I didn't know $\endgroup$ Jun 10, 2020 at 8:35

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .