wild bouncing


I’ve made a cube that constantly (using the always sensor) applies an upward force to itself, but only if it is on the ground. The “local” (L) flag/button is NOT set. When I set its bounds to “box”, and run the game, it bounces wildly all over the place. But it doesn’t do this before I explicitly set the bounds.

Why is it doing this? If no other forces acting on the object, then it should just bounce upward. Does the engine have some randomness to it?


if you drop a rigid body box onto a plane so that a corner hits the floor without the upwards force being applied, you will notice that it will bounce to a side and then land and level out like a normal object would. the upward force seems to exaggerate this. making the cube not a rigid body and only dynamic would get rid of the problem. but not sure if that will work for you.

edit: meaning i am not sure what you are using the bouncing cube for. so i don’t know whether you need it to be a rigid body or not.

That makes sense, but if it’s a perfect cube, and the force is applied from the center of the object, shouldn’t the bottom hit the plane flat on?
And I was just experimenting with Blender when I noticed this, by the way.

Try to add materials to the objects?!

Both the cube and the place it bounces off have materials. The bouncing doesn’t really matter, since it’s not causing me any problems. :slight_smile: Thanks anyway.

Game engine physics aren’t “perfect” simulations, just like real life can’t really be perfect. Yes, in theory a perfect cube landing on a perfectly flat plane shouldn’t do anything but bounce straight up, but as I said, the physics aren’t perfect. Try making a rigid body cube, setting its bounds to cube, and dropping it from about 10 blender units above a plane. It will rotate a little, even though it shouldn’t.

You can solve this rotation by not using rigid body, but aside from that it’s just a limitation.

Ok, thanks. That’s kind of what I thought, but I wanted to be sure (since I’m new to 3D game engines and physics simulations).