How To Make Parallax Background Infinite Scrolling Unity

E.Caroline

3 min read

·

08-02-2025

1

0

Share

Creating an infinite scrolling parallax background in Unity adds a captivating sense of depth and movement to your games. This tutorial will guide you through the process, breaking it down into manageable steps. We'll cover everything from setting up the scene to implementing the scrolling effect, ensuring your background seamlessly repeats without any jarring interruptions.

Understanding Parallax Scrolling

Parallax scrolling is a technique where background elements move slower than foreground elements, creating an illusion of depth and perspective. This effect is particularly effective in side-scrolling games, but can be adapted for other genres as well. In an infinite scrolling implementation, the background seamlessly loops, creating the impression of endless movement.

Setting Up the Scene in Unity

1. Create your background images: You'll need at least two images for your parallax background. More images will provide a richer visual effect and greater depth. Ideally, these images should seamlessly tile horizontally. If they don't, you'll need to edit them to ensure a smooth transition when looping.

2. Import images into Unity: Import your background images as sprites into your Unity project. Ensure the "Sprite" import type is selected. Consider using a sprite sheet for optimal performance with multiple background layers.

3. Create GameObjects: Create several GameObjects in your Unity scene, one for each layer of your parallax background. These GameObjects will act as containers for your sprite renderers. Name them clearly (e.g., "BackgroundLayer1", "BackgroundLayer2").

4. Add Sprite Renderers: Add a Sprite Renderer component to each GameObject. Assign the corresponding background image to each Sprite Renderer. Adjust the sorting order in the Sprite Renderer component to ensure correct layering. Farther background layers should have a lower sorting order.

5. Positioning: Position the GameObjects strategically to create the desired parallax effect. Background layers should be placed further away from the camera than foreground layers.

Implementing the Infinite Scrolling Script

This is where the magic happens. We'll use C# to create a script that handles the parallax scrolling and infinite looping.

using UnityEngine;

public class ParallaxBackground : MonoBehaviour
{
    public float scrollingSpeed = 1f; // Adjust this value to control scrolling speed
    public float parallaxFactor = 0.5f; // Adjust this value to control parallax effect

    private float offsetX;
    private Renderer backgroundRenderer;

    void Start()
    {
        backgroundRenderer = GetComponent<Renderer>();
    }

    void Update()
    {
        offsetX += scrollingSpeed * Time.deltaTime * parallaxFactor;
        backgroundRenderer.material.mainTextureOffset = new Vector2(offsetX, 0f);

        //Check if the background has moved completely offscreen to reset
        if (offsetX > backgroundRenderer.material.mainTextureScale.x)
        {
            offsetX -= backgroundRenderer.material.mainTextureScale.x;
        }
    }
}

Explanation:

• scrollingSpeed: Controls the overall speed of the scrolling.
• parallaxFactor: Controls the strength of the parallax effect. Lower values create a stronger parallax effect.
• offsetX: Tracks the horizontal offset of the background.
• backgroundRenderer: Accesses the Sprite Renderer component of the GameObject.
• The Update() function updates the texture offset based on scrolling speed and parallax factor.
• The conditional statement handles the looping, resetting the offset when it exceeds the texture's width.

Attaching the Script and Fine-Tuning

1. Attach the script: Create a new C# script named "ParallaxBackground.cs" and paste the code above into it. Attach this script to each GameObject representing a layer of your parallax background.

2. Adjust parameters: Modify the scrollingSpeed and parallaxFactor values in the Inspector for each layer to fine-tune the parallax effect. Background layers should typically have lower scrollingSpeed values and higher parallaxFactor values than foreground layers.

3. Test and iterate: Run your game and adjust the parameters until you achieve the desired effect.

Optimizing for Performance

• Texture size: Use appropriately sized textures. Larger textures require more processing power.
• Layer count: Minimize the number of parallax layers for improved performance.
• Sprite Sheet: Use sprite sheets instead of individual images where possible.
• Pooling: For very complex scenes, consider using object pooling to recycle GameObjects.

By following these steps, you can create a visually stunning and performant infinite scrolling parallax background for your Unity games. Remember to experiment with different speeds and parallax factors to achieve the perfect look and feel for your project. Happy developing!