RigidBody

Intro

A Rigidbody in Unity is a component that enables a GameObject to react to physics, like gravity and collisions. It allows movement through forces making the object behave more realistically in the game world.

Here are some typical configurations using a RigidBody:

Indication

• Blocking + Moving

  • Object moves and responds to gravity or impulses, can collide and bounce with other elements

  • Useful for: moving car, falling domino, basket-ball

  • Set: Collider + RigidBody

  • Function: void OnCollisionEnter(Collision collision)

• Blocking + Immobile

  • Object doesn’t move, but other objects can bump into it

  • Useful for: walls, floor

  • Set: Collider only

  • Function: None

Avertissement

Beware, when the trigger of the collider is activated, this implicitly disables the rigidbody of the gameobject.

Avertissement

In previous project, we have moved objects using the translate or rotate function.

Exercise

Basic setup

We begin our study by adding a RigidBody to the sphere.

• Create a cube and and assign it a color

  • Scale the cube to create a ground

• Select the sphere

  • In the Inspector, click on the button Add Component

  • Select RigidBody

  • In the RigidBody section, check: Use Gravity

  

• If you want the camera to shoot the same view as the scene view

  • In the Hierarchy, select the camera

  • Right click and select Align With View

• Enter Play mode

  

What happened?

• The sphere has a Rigidbody, moreover it is affected by gravity so it falls

• The ground don’t have a Rigidbody, it’s a static object, it cant move

• Both the sphere and the ground have a Collider, allowing them to come into contact, which stops the sphere’s fall

Simulation

We add some new elements to the scene; try to reproduce the scene below.

Some hints:

• Analyze which object has a RigidBody: is the object moving or not?

• Detect which object is affected by gravity: it is falling or not ?

• Enable all options correctly