Unity physics about collision and energy

Question

I have been working on a Unity ping pong game using the Leap Motion. I use rigidbody.MovePosition() to move the paddle. However, when I hit the ball (which uses gravity), the paddle launches it too far. Even when I change the masses of both, it doesn't do anything.

What variable should I change to reduce this energy going into the ball?

by any chance are you using a bounce material on the paddle? — lemunk
Yes, I am. I'm using a physicMaterial with a coefficient of resitution (bounciness). — Sonu Bae
then go into the material you can see a properties called "bounce" it refers to the energy absorb rate that you can fine tune to suit your needs — lemunk

Daniel Bank Daniel Bank · Accepted Answer · 2013-10-31T18:19:41

From the following link.

"MovePosition will put your object at the target location, no matter what. It may push aside other objects in a realistic way, or may blast them out of the way, or may just pass right through them. But it will gladly move you through a solid wall or a mountain.

If you're using MovePosition on a rigidbody to add from where you currently are, it looks like AddForce. With AddForce, the physics step does all the work: applies your velocity, sees the collision and handles the bounce. With MovePosition, the physics step sees you're mysteriously overlapping a solid object. If it isn't too much, it will bounce you apart."

You won't need to use MovePosition. Instead, you can figure out the direction of the shot (based on the position of the ball relative to the paddle). Then you can add an impulse force in that direction to the ball.

Pseudo-code (from the following link):

Vector3 shootDir = ballPosition - paddlePosition; // Calculate direction of the shot
shootDir.Normalize(); // Normalize the shot vector
ball.AddForce(shootDir * speed, ForceMode.Impulse); //Add impulse force in correct direction.

Credit due to Owen Reynolds and Tim Michels.

Unity physics about collision and energy

1 Answers