Collision

Collision System Overview:

The provided code defines an abstract class CollisionBase that serves as the foundation for a collision system in a Unity game. This system is designed to handle collision events (enter, stay, exit) involving a specified type of collider (TCollider). The implementation includes event handling, collision detection, and collider management.

1. Generic CollisionBase Class:

   • This is an abstract class (CollisionBase<TCollider, TPhysicScene>) that serves as the base for collision handling.

   • It extends MonoBehaviour and implements the IEditableForEditor interface.

   • It has three events (OnCollisionEnter, OnCollisionStay, OnCollisionExit) that can be subscribed to for reacting to collisions.

   • It includes properties and methods for managing collision layers, garbage collider size, center position, and physics scenes.

2. Colliders and Garbage Collection:

   • The class handles collisions using an array of colliders (m_garbageColliders) and a list (_colliders) to keep track of colliders involved in collisions.

   • The size of the garbage collider array is set by GarbageColliderSize.

   • The HandleColliderCleaner method is responsible for cleaning up null colliders from the list and resetting the garbage colliders.

3. Physics Scene and Layer Management:

   • The class has a physics scene (TPhysicScene m_physicsScene) that is updated using the UpdatePhysicScene method.

   • The collision layer is set using the SetLayer method, which takes a LayerMask parameter.

4. Collision Handling:

   • The main collision handling logic is in the FixedUpdate method, which is executed at a fixed time interval.

   • The CalculateCollision method is abstract and should be implemented by subclasses to define specific collision logic.

   • The class handles new collisions, continued collisions, and collisions exits using the HandleNewCollisions, HandleContinuedCollisions, and HandleCollisionsExit methods, respectively.

5. Event Handling:

   • The class provides methods (HandleCollisionEnter, HandleCollisionStay, HandleCollisionExit) to trigger the corresponding events when collisions occur.

6. Editor Integration:

   • The class implements an interface (IEditableForEditor) to support editor-specific functionality. The Editable property is likely used for toggling whether the collision system is editable in the Unity Editor.

7. Initialization:

   • The Awake method sets the initial capacity of colliders and garbage colliders using the SetCollidersCapacity method.

   • The Start method initializes the physics scene using GetPhysicScene.

8. Error Handling:

   • If the physics scene is not set during the FixedUpdate, an error message is logged to the console.

How to Use:

1. Inheritance:

   • Create a class that inherits from CollisionBase.

   • Implement the abstract methods (CalculateCollision and GetPhysicScene) to define specific collision behavior.

2. Event Handling:

   • Subscribe to the collision events (OnCollisionEnter, OnCollisionStay, OnCollisionExit) in the derived class to execute custom logic when collisions occur.

3. Unity Editor Integration:

   • Utilize the Editable property for debugging purposes, making the collision system visually editable in the Unity Editor.

4. Layer Filtering:

   • Set the m_layer property to filter collisions based on layers.

Example Usage:

public class MyCollisionSystem : CollisionBase<Collider3D, PhysicsScene>
{
    // Implement abstract methods
    protected override void CalculateCollision()
    {
        // Custom collision calculation logic
    }

    protected override void GetPhysicScene()
    {
        // Custom physics scene retrieval logic
    }
}

public class MyCharacterController : MonoBehaviour
{
    [SerializeField] private MyCollisionSystem _collision;

    // Custom event handling
    private void Awake()
    {
        _collision.OnCollisionEnter += HandleCustomCollisionEnter;
    }
    
    private void HandleCustomCollisionEnter(Collider coll)
    {
        // Custom logic for handling collision enter
    }
}

Benefits:

• Provides a flexible foundation for implementing collision systems in Unity.

• Offers a modular structure for handling different types of colliders and physics scenes.

• Enables event-driven collision handling for easy customization.

Considerations:

• Ensure that the abstract methods are implemented in derived classes to define specific collision behavior.

• Customize the event handling methods (HandleCollisionEnter, HandleCollisionStay, HandleCollisionExit) for the desired behavior in the derived class.

• The system is designed for 3D physics; modifications may be necessary for 2D physics.