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How to Create a Scroll Bar in Scratch Games

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GG

GardenGameDev

Posted on July 28, 2025 • Intermediate

🛒 Need help creating a scroll bar for my shop

Hey everyone! I’m working on a garden growing game and I need to create a scroll bar for my shop system. I have all my shop items in one sprite and want to use clones to display them.

I’m running into two main issues:

  • How to make a functional scroll bar that works with cloned items
  • When I create clones and change Y by -75, they stack on top of each other instead of spacing properly
  • Need the scroll to work smoothly with arrow keys or mouse wheel

I want players to be able to scroll through all the available items in the shop. Any help would be amazing! 🌱

UI

UIExpert_Sam

Replied 1 hour later • ⭐ Best Answer

Perfect question @GardenGameDev! Creating a scroll bar with clones is a common challenge. Here’s a complete solution that will solve your positioning issues:

📋 Scroll Bar System Flow

Here’s how a proper scroll system works:

flowchart TD A[🚀 Initialize Shop] --> B[Set Scroll Position = 0] B --> C[Create Item Clones] C --> D[🎮 User Input] D --> E{Scroll Direction?} E -->|Up Arrow| F[Scroll Position + 1] E -->|Down Arrow| G[Scroll Position - 1] E -->|Mouse Wheel| H[Detect Wheel Direction] F --> I[Check Scroll Limits] G --> I H --> I I --> J[Update All Clone Positions] J --> K[Calculate: Y = (Index - Scroll) * Height] K --> L{Item Visible?} L -->|Yes| M[Show Clone] L -->|No| N[Hide Clone] M --> O[🔄 Wait for Next Input] N --> O O --> D style A fill:#e1f5fe style I fill:#fff3e0 style K fill:#e8f5e8 style O fill:#f3e5f5

🔧 Step 1: Initialize the Scroll System

First, set up your main variables and create the shop items:

    when flag clicked
// Initialize scroll variables
set [scroll_position v] to [0]
set [item_count v] to [12]  // Total number of shop items
set [item_height v] to [80]  // Spacing between items
set [visible_items v] to [5]  // How many items visible at once
set [shop_top_y v] to [150]  // Top position of shop area

// Create all shop items
create shop items :: custom
update item positions :: custom

📦 Step 2: Create Shop Items with Proper IDs

Create clones with unique identifiers:

    define create shop items
// Clear any existing clones
delete all clones

// Create clones with proper indexing
set [current_item v] to [1]
repeat (item_count)
set [clone_id v] to (current_item)
create clone of [myself v]
change [current_item v] by [1]
end

🎯 Step 3: Clone Positioning Logic

This is the key part that fixes your stacking issue:

    when I start as a clone
// Store this clone's ID
set [my_id v] to (clone_id)

// Set the correct costume for this item
switch costume to (my_id)

// Position this clone correctly
update my position :: custom

define update my position
// Calculate Y position based on scroll and item ID
set [calculated_y v] to ((shop_top_y) - (((my_id) - (scroll_position)) * (item_height)))

// Position the clone
go to x: [0] y: (calculated_y)

// Show/hide based on visibility
if <<(calculated_y) > [(shop_top_y) - ((visible_items) * (item_height))]> and <(calculated_y) < [(shop_top_y) + (item_height)]>> then
show
else
hide
end

⬆️ Step 4: Scroll Controls

Handle user input for scrolling:

    // Scroll up (show earlier items)
when [up arrow v] key pressed
if <(scroll_position) > [0]> then
change [scroll_position v] by [-1]
update item positions :: custom
end

// Scroll down (show later items)
when [down arrow v] key pressed
set [max_scroll v] to ((item_count) - (visible_items))
if <(scroll_position) < (max_scroll)> then
change [scroll_position v] by [1]
update item positions :: custom
end

// Update all clone positions
define update item positions
broadcast [update positions v]

// In clone script:
when I receive [update positions v]
update my position :: custom

🖱️ Step 5: Mouse Wheel Support (Advanced)

For even better user experience:

    // Detect mouse wheel scrolling
when flag clicked
forever
if <mouse down?> then
set [last_mouse_y v] to (mouse y)
wait until <not <mouse down?>>
set [mouse_delta v] to ((mouse y) - (last_mouse_y))

if <(mouse_delta) > [10]> then
// Scrolled up
if <(scroll_position) > [0]> then
change [scroll_position v] by [-1]
update item positions :: custom
end
else
if <(mouse_delta) < [-10]> then
// Scrolled down
set [max_scroll v] to ((item_count) - (visible_items))
if <(scroll_position) < (max_scroll)> then
change [scroll_position v] by [1]
update item positions :: custom
end
end
end
end
end

🎨 Step 6: Visual Scroll Bar (Optional)

Add a visual scroll bar indicator:

    // Create scroll bar sprite
when flag clicked
forever
// Calculate scroll bar position
set [scroll_percent v] to ((scroll_position) / ((item_count) - (visible_items)))
set [bar_y v] to ((shop_top_y) - ((scroll_percent) * ((visible_items) * (item_height))))

// Position scroll bar
go to x: [200] y: (bar_y)

// Show scroll bar only when needed
if <(item_count) > (visible_items)> then
show
else
hide
end
end

This system will give you smooth scrolling with proper clone positioning! The key is calculating each clone’s position based on its ID and the current scroll position. 🛒✨

GardenGameDev

Replied 45 minutes later

@UIExpert_Sam This is incredible! 🎉 The positioning calculation makes perfect sense now.

I implemented your solution and my shop scroll bar works perfectly! The clones no longer stack on top of each other, and the scrolling is super smooth. Thank you so much!

The visual scroll bar is a nice touch too - really makes it feel professional! 🌟

CD

CloneDeveloper

Replied 2 hours later

Great solution! 👏 I’d also suggest adding some performance optimizations:

  • Lazy loading: Only create clones for visible items + a few buffer items
  • Smooth scrolling: Add easing animations between scroll positions
  • Touch support: Detect touch gestures for mobile-like scrolling
  • Scroll momentum: Add inertia when scrolling quickly

These features can make your scroll bar feel even more professional! 🚀

VB

Vibelf_Community

Pinned Message • Moderator

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