Rigid Body Physics: Unity and PhysX

Rigid Bodies in Unity

• The Rigidbody component can be assigned to GameObjects in Unity to configure them as rigid bodies, which do not deform or change shape under physics forces.
• The Rigidbody component provides a way to control the movement and position of a GameObject, allowing for physics-based simulation.

Rigidbody Properties and Movement

• Rigidbody properties should be used to move a GameObject in Unity when physics-based movement is required, such as when applying forces, torques, or velocities.
• If the Transform is changed directly on a GameObject with a Rigidbody, it will be overridden by the physics engine, leading to unexpected behavior.

API and Forces

• The Rigidbody class represents a rigid body in the Unity API.
• The primary class used to add forces to a GameObject is the Rigidbody class.
• The AddTorque method of the Rigidbody class is used to apply torque to a GameObject.

Kinematic Rigid Bodies

• A kinematic Rigidbody is a type of Rigidbody that has non-physics-based movement, allowing it to move without being affected by the physics engine.
• The Is Kinematic property of a Rigidbody defines a GameObject as non-physics-based and removes it from the control of the physics engine.
• A kinematic Rigidbody can move and collide with a Rigidbody that has physics-based movement, but it will not be affected by the collision.

Sleep and Wake

• Unity sets a Rigidbody to 'sleep' when it has come to rest and is no longer moving or colliding with other objects.
• If a Rigidbody receives a collision or force while it is 'sleeping', it will be 'woken up' and begin to move and respond to physics forces again.
• The Rigidbody can be manually woken up using the WakeUp method.

Learn about simulating physics-based behavior such as movement, gravity, collision, and joints by configuring GameObjects as rigid bodies in Unity’s PhysX system.