Creating a scrolling background is a popular technique in Scratch projects. This effect helps games and animations look more dynamic and interactive. Many games use scrolling backgrounds to give the illusion of movement or travel within a virtual world.
Understanding how scrolling backgrounds work in Scratch can help with building more advanced projects. For those new to this concept, it introduces important programming concepts related to graphics and logic.
A scrolling background in Scratch creates the effect where background images move continuously across the screen. Think of it like looking out a car window – the scenery appears to move past you, but you’re staying in the same spot!
In Scratch, this works by moving background sprites (not backdrops) while keeping your main character in a fixed position. The background tiles slide across the stage, creating the illusion that your character is walking, running, or driving through a larger world.
This technique is super useful for:
Scrolling backgrounds let you create worlds that are much bigger than Scratch’s stage. Instead of cramming everything into one small screen, you can build long levels that feel like real adventures!
Your main sprite stays near the center of the stage while the world moves around it. This approach makes games feel more professional and engaging. Players get excited when they see new scenery appearing as they explore.
Key benefits include:
Start by opening a new Scratch project and deleting the default cat sprite. You’ll work with sprites for your scrolling elements, not backdrops.
Create your background tiles first. These are sprites that will repeat to form your scrolling world. Design them so they connect seamlessly – the right edge of one tile connects perfectly with the left edge of the next tile.
Essential variables to create:
Make these variables “For all sprites” so every part of your project can use them. Set scrollX to 0 and speed to 5 when your project starts.
Your background sprite needs multiple copies (clones) to fill the entire stage. Plan for at least 3-4 tiles visible at once to avoid gaps during scrolling.
Open the Variables section and make two new variables: scrollX and speed. These control your scrolling camera system.
When the green flag is clicked, set scrollX to 0 and speed to 5. These starting values work well for most projects.
Draw a background tile that’s about 200-300 pixels wide. Make sure the left and right edges match perfectly so tiles connect without visible seams.
Important design tips:
Create enough clones of your background sprite to cover the stage width plus extra space. Use this script for each background clone:
set x to (starting x position - scrollX)
Space your tiles so they touch but don’t overlap. If your tile is 240 pixels wide, place them at positions like -240, 0, 240, 480, etc.
When arrow keys are pressed, change the scrollX variable instead of moving your player sprite directly. For moving right, increase scrollX by the speed value. For moving left, decrease scrollX by the speed value.
This makes all background tiles shift together, creating the scrolling effect while your player appears to move through the world.
When a background tile moves completely off one side of the stage, reset its position to the opposite side. This creates an infinite scrolling loop.
Use this logic: if a tile’s x position is less than -480 (off the left), set it to x position + (number of tiles × tile width).
Parallax scrolling makes backgrounds look more realistic by moving different layers at different speeds. Objects closer to the camera move faster, while distant objects move slower.
Make separate sprites for foreground, middle ground, and background elements. For example:
Each layer moves at a fraction of the main scroll speed. Try these multipliers:
This creates a convincing depth effect as players move through your game world.
All layers use the same scrollX variable but multiply it by their speed factor. This keeps everything moving together while maintaining the depth illusion.
Vertical scrolling works exactly like horizontal scrolling but uses a scrollY variable instead. This technique works great for top-down games or flying games.
Create a scrollY variable and set it to 0 when your project starts. When players press up/down arrows, change scrollY by your speed value.
For your background sprites, use:
set y to (starting y position - scrollY)
Two-axis scrolling combines both techniques. Your background sprites use both variables:
set x to (starting x position - scrollX)
set y to (starting y position - scrollY)
This creates free movement in all directions, perfect for exploration games or space shooters.
Gaps appear when tiles don’t line up perfectly. Double-check that your tile width matches the spacing between clones. If your tile is 240 pixels wide, space clones exactly 240 pixels apart.
Use whole numbers for all positions. Decimal positions can create tiny gaps that look unprofessional.
Flickering happens when sprites rapidly change positions or visibility. Keep your scrolling smooth by updating positions once per frame, not multiple times.
Quick fixes:
Too many sprites or clones can slow down your project. Limit background clones to only what’s visible on screen plus one extra tile on each side.
Delete clones that move far off-screen and create new ones only when needed. This keeps your project running smoothly even with complex scrolling backgrounds.
No, Scratch backdrops cannot move or change position through code blocks. Backdrops stay fixed in place on the stage. You need sprites to create scrolling effects because only sprites can change their x and y positions during the game.
Put your scrollX changes inside the same scripts that detect player movement. When a player presses the right arrow key, increase scrollX in the same script block. When no keys are pressed, don’t change scrollX, and the background will stay still.
Create road sprites that tile vertically instead of horizontally. Use scrollY to make road segments move downward toward your car sprite. Set your car sprite to stay near the bottom center of the stage while road tiles scroll from top to bottom, simulating forward driving motion.
Scrolling backgrounds use sprites that can move and repeat seamlessly across the stage. Moving backdrops refers to switching between different backdrop images, which creates scene changes rather than smooth scrolling motion. For continuous movement effects, always use sprites.
Now you have all the tools to create amazing scrolling backgrounds in your Scratch projects! Start with a simple horizontal scroll, then experiment with parallax layers and vertical movement as you get more comfortable.
The key is starting simple and adding complexity gradually. Your first scrolling background might just be a basic repeating pattern, and that’s perfectly fine. Each project teaches you something new about game development and programming.
Ready to take your Scratch skills to the next level? Sign up for a free trial class where expert instructors can help you master advanced techniques like scrolling backgrounds, game physics, and interactive storytelling. Every child deserves access to world-class technology education that makes learning fun and engaging!
