Create a gist now

Instantly share code, notes, and snippets.

What would you like to do?
Multi directionnal infinite scrolling script.This is related to the tutorial http://pixelnest.io/tutorials/2d-game-unity/parallax-scrolling/
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
/// <summary>
/// Parallax scrolling script that should be assigned to a layer
///
/// This is related to the tutorial http://pixelnest.io/tutorials/2d-game-unity/parallax-scrolling/
///
/// See the result: http://pixelnest.io/tutorials/2d-game-unity/parallax-scrolling/-img/multidir_scrolling.gif
/// </summary>
public class ScrollingScript : MonoBehaviour
{
/// <summary>
/// Scrolling speed
/// </summary>
public Vector2 speed = new Vector2(10, 10);
/// <summary>
/// Moving direction
/// </summary>
public Vector2 direction = new Vector2(-1, 0);
/// <summary>
/// Movement should be applied to camera
/// </summary>
public bool isLinkedToCamera = false;
/// <summary>
/// Background is inifnite
/// </summary>
public bool isLooping = false;
private List<SpriteRenderer> backgroundPart;
private Vector2 repeatableSize;
void Start()
{
// For infinite background only
if (isLooping)
{
//---------------------------------------------------------------------------------
// 1 - Retrieve background objects
// -- We need to know what this background is made of
// -- Store a reference of each object
// -- Order those items in the order of the scrolling, so we know the item that will be the first to be recycled
// -- Compute the relative position between each part before they start moving
//---------------------------------------------------------------------------------
// Get all part of the layer
backgroundPart = new List<SpriteRenderer>();
for (int i = 0; i < transform.childCount; i++)
{
Transform child = transform.GetChild(i);
SpriteRenderer r = child.GetComponent<SpriteRenderer>();
// Only visible children
if (r != null)
{
backgroundPart.Add(r);
}
}
if (backgroundPart.Count == 0)
{
Debug.LogError("Nothing to scroll!");
}
// Sort by position
// -- Depends on the scrolling direction
backgroundPart = backgroundPart.OrderBy(t => t.transform.position.x * (-1 * direction.x)).ThenBy(t => t.transform.position.y * (-1 * direction.y)).ToList();
// Get the size of the repeatable parts
var first = backgroundPart.First();
var last = backgroundPart.Last();
repeatableSize = new Vector2(
Mathf.Abs(last.transform.position.x - first.transform.position.x),
Mathf.Abs(last.transform.position.y - first.transform.position.y)
);
}
}
void Update()
{
// Movement
Vector3 movement = new Vector3(
speed.x * direction.x,
speed.y * direction.y,
0);
movement *= Time.deltaTime;
transform.Translate(movement);
// Move the camera
if (isLinkedToCamera)
{
Camera.main.transform.Translate(movement);
}
// Loop
if (isLooping)
{
//---------------------------------------------------------------------------------
// 2 - Check if the object is before, in or after the camera bounds
//---------------------------------------------------------------------------------
// Camera borders
var dist = (transform.position - Camera.main.transform.position).z;
float leftBorder = Camera.main.ViewportToWorldPoint(new Vector3(0, 0, dist)).x;
float rightBorder = Camera.main.ViewportToWorldPoint(new Vector3(1, 0, dist)).x;
var topBorder = Camera.main.ViewportToWorldPoint(new Vector3(0, 0, dist)).y;
var bottomBorder = Camera.main.ViewportToWorldPoint(new Vector3(0, 1, dist)).y;
// Determine entry and exit border using direction
Vector3 exitBorder = Vector3.zero;
Vector3 entryBorder = Vector3.zero;
if (direction.x < 0)
{
exitBorder.x = leftBorder;
entryBorder.x = rightBorder;
}
else if (direction.x > 0)
{
exitBorder.x = rightBorder;
entryBorder.x = leftBorder;
}
if (direction.y < 0)
{
exitBorder.y = bottomBorder;
entryBorder.y = topBorder;
}
else if (direction.y > 0)
{
exitBorder.y = topBorder;
entryBorder.y = bottomBorder;
}
// Get the first object
SpriteRenderer firstChild = backgroundPart.FirstOrDefault();
if (firstChild != null)
{
bool checkVisible = false;
// Check if we are after the camera
// The check is on the position first as IsVisibleFrom is a heavy method
// Here again, we check the border depending on the direction
if (direction.x != 0)
{
if ((direction.x < 0 && (firstChild.transform.position.x < exitBorder.x))
|| (direction.x > 0 && (firstChild.transform.position.x > exitBorder.x)))
{
checkVisible = true;
}
}
if (direction.y != 0)
{
if ((direction.y < 0 && (firstChild.transform.position.y < exitBorder.y))
|| (direction.y > 0 && (firstChild.transform.position.y > exitBorder.y)))
{
checkVisible = true;
}
}
// Check if the sprite is really visible on the camera or not
if (checkVisible)
{
//---------------------------------------------------------------------------------
// 3 - The object was in the camera bounds but isn't anymore.
// -- We need to recycle it
// -- That means he was the first, he's now the last
// -- And we physically moves him to the further position possible
//---------------------------------------------------------------------------------
if (firstChild.IsVisibleFrom(Camera.main) == false)
{
// Set position in the end
firstChild.transform.position = new Vector3(
firstChild.transform.position.x + ((repeatableSize.x + firstChild.bounds.size.x) * -1 * direction.x),
firstChild.transform.position.y + ((repeatableSize.y + firstChild.bounds.size.y) * -1 * direction.y),
firstChild.transform.position.z
);
// The first part become the last one
backgroundPart.Remove(firstChild);
backgroundPart.Add(firstChild);
}
}
}
}
}
}

Thank you very much! I'm a beginning game developer, I have enjoyed this tutoria and acquired a basic foundation to build games! Thanks again!

2 things i noticed:
When the player/camera stops moving, the BG keeps moving, even thought it is linked to camera,
also, all speeds seem to be either the same or faster than the camera speed. I used the exact values used in your tutorial.

Owner

valryon commented Mar 4, 2015

Updated for Unity 5

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment