Help with rigidbody object sitting on top of another (moving) rigidbody

Unity Engine
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1

Hi all,
I’m fairly new to Unity, and as an exercise I decided to make a simple coin pusher game. The coins will fall from the top, land on a shelf, and push other coins off the shelf into the tray below.

I have one script which moves the shelf back and forth, and rigidbody coins falling from above.
The problem I’m having is that the coins do not move with the shelf at all, and instead sit stationary on top as the shelf moves back and forth below.

I then added a script to add a fixed joint to the coins on collision with the shelf, and now the coins do move with the shelf, but are frozen in place as soon as they touch. I’m trying to make it so the coins can follow the position of the shelf, and still be pushed off.

I have searched high and low for a solution to this problem, and so far I have not found anything all too helpful.
Can anybody offer me any advice on how to go about this? I have also tried to read the manual for Unity, however this is not ideal because I don’t actually know what is causing this behavior.

Thank you very much in advance.

2

Hi there,
Have you assign a physical material to both the coins and shelf since the motion is caused by friction, also make sure that you are driving the shelf back and forth through physics not simply modifying the transform position. It should work with these set up.

3

Hi there Lokeyyyy, thanks for answering.
I have indeed applied a physics material to my coins and my shelf, and this unfortunately does not seem to work. However, it did not cross my mind that the way the shelf is moved could be the culprit for this problem. I do believe it is set as a modifying transform rather than a force.
I am going to redo the movement with a force and try it again. I will come back with the results.

Thank you very much, once again.

4

Hello again Lokeyyyy, I just thought I’d let you know that your suggestion was totally right, and thanks to you I made great progress in the creation of my first game. Even if it is quite simple, it’s a big step for a beginner, so thank you very much once again.

5

You’re welcome, good luck with your project