2D Roguelike Unity example project interesting snippets

MovingObject.cs

using UnityEngine;
using System.Collections;

namespace Completed
{
	//The abstract keyword enables you to create classes and class members that are incomplete and must be implemented in a derived class.
	public abstract class MovingObject : MonoBehaviour
	{
		public float moveTime = 0.1f;			//Time it will take object to move, in seconds.
		public LayerMask blockingLayer;			//Layer on which collision will be checked.
		
		
		private BoxCollider2D boxCollider; 		//The BoxCollider2D component attached to this object.
		private Rigidbody2D rb2D;				//The Rigidbody2D component attached to this object.
		private float inverseMoveTime;			//Used to make movement more efficient.
		
		
		//Protected, virtual functions can be overridden by inheriting classes.
		protected virtual void Start ()
		{
			//Get a component reference to this object's BoxCollider2D
			boxCollider = GetComponent <BoxCollider2D> ();
			
			//Get a component reference to this object's Rigidbody2D
			rb2D = GetComponent <Rigidbody2D> ();
			
			//By storing the reciprocal of the move time we can use it by multiplying instead of dividing, this is more efficient.
			inverseMoveTime = 1f / moveTime;
		}
		
		
		//Move returns true if it is able to move and false if not. 
		//Move takes parameters for x direction, y direction and a RaycastHit2D to check collision.
		protected bool Move (int xDir, int yDir, out RaycastHit2D hit)
		{
			//Store start position to move from, based on objects current transform position.
			Vector2 start = transform.position;
			
			// Calculate end position based on the direction parameters passed in when calling Move.
			Vector2 end = start + new Vector2 (xDir, yDir);
			
			//Disable the boxCollider so that linecast doesn't hit this object's own collider.
			boxCollider.enabled = false;
			
			//Cast a line from start point to end point checking collision on blockingLayer.
			hit = Physics2D.Linecast (start, end, blockingLayer);
			
			//Re-enable boxCollider after linecast
			boxCollider.enabled = true;
			
			//Check if anything was hit
			if(hit.transform == null)
			{
				//If nothing was hit, start SmoothMovement co-routine passing in the Vector2 end as destination
				StartCoroutine (SmoothMovement (end));
				
				//Return true to say that Move was successful
				return true;
			}
			
			//If something was hit, return false, Move was unsuccesful.
			return false;
		}
		
		
		//Co-routine for moving units from one space to next, takes a parameter end to specify where to move to.
		protected IEnumerator SmoothMovement (Vector3 end)
		{
			//Calculate the remaining distance to move based on the square magnitude of the difference between current position and end parameter. 
			//Square magnitude is used instead of magnitude because it's computationally cheaper.
			float sqrRemainingDistance = (transform.position - end).sqrMagnitude;
			
			//While that distance is greater than a very small amount (Epsilon, almost zero):
			while(sqrRemainingDistance > float.Epsilon)
			{
				//Find a new position proportionally closer to the end, based on the moveTime
				Vector3 newPostion = Vector3.MoveTowards(rb2D.position, end, inverseMoveTime * Time.deltaTime);
				
				//Call MovePosition on attached Rigidbody2D and move it to the calculated position.
				rb2D.MovePosition (newPostion);
				
				//Recalculate the remaining distance after moving.
				sqrRemainingDistance = (transform.position - end).sqrMagnitude;
				
				//Return and loop until sqrRemainingDistance is close enough to zero to end the function
				yield return null;
			}
		}
		
		
		//The virtual keyword means AttemptMove can be overridden by inheriting classes using the override keyword.
		//AttemptMove takes a generic parameter T to specify the type of component we expect our unit to interact with if blocked (Player for Enemies, Wall for Player).
		protected virtual void AttemptMove <T> (int xDir, int yDir)
			where T : Component
		{
			//Hit will store whatever our linecast hits when Move is called.
			RaycastHit2D hit;
			
			//Set canMove to true if Move was successful, false if failed.
			bool canMove = Move (xDir, yDir, out hit);
			
			//Check if nothing was hit by linecast
			if(hit.transform == null)
				//If nothing was hit, return and don't execute further code.
				return;
			
			//Get a component reference to the component of type T attached to the object that was hit
			T hitComponent = hit.transform.GetComponent <T> ();
			
			//If canMove is false and hitComponent is not equal to null, meaning MovingObject is blocked and has hit something it can interact with.
			if(!canMove && hitComponent != null)
				
				//Call the OnCantMove function and pass it hitComponent as a parameter.
				OnCantMove (hitComponent);
		}
		
		
		//The abstract modifier indicates that the thing being modified has a missing or incomplete implementation.
		//OnCantMove will be overriden by functions in the inheriting classes.
		protected abstract void OnCantMove <T> (T component)
			where T : Component;
	}
}