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How to detect sprite movement direction and state in Scratch

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CE

CodeExplorer_Sam

Posted on July 26, 2025 • Intermediate

🎯 Need help detecting sprite movement states

Hey everyone! I’m working on a project with fly sprites that have different movement behaviors. Here’s my situation:

  • My Fly sprite moves randomly most of the time
  • When a specific event happens, it should move to coordinates X: 0 Y: -150
  • I need to detect when it’s moving to those specific coordinates vs. moving randomly
  • I also need to detect when the sprite isn’t moving at all

The tricky part is that I’m using clones, and each clone might have different movement states. How can I track this properly? 🤔

SM

SpriteManager_Pro

Replied 1 hour later • ⭐ Best Answer

Great question @CodeExplorer_Sam! This is a common challenge when working with clones and movement states. Here’s a comprehensive solution:

🎯 Movement Detection System

Here’s how to track different movement states for each clone:

flowchart TD A[🚀 Clone Created] --> B[Set Movement State] B --> C{Current State?} C -->|Random| D[Random Movement] C -->|Target| E[Move to Target] C -->|Idle| F[No Movement] D --> G[Update Position Randomly] E --> H[Move Toward X:0 Y:-150] F --> I[Stay in Place] G --> J[Check for State Change] H --> K{Reached Target?} I --> J K -->|Yes| L[Set State to Idle] K -->|No| E J --> M{Event Triggered?} M -->|Yes| N[Change to Target State] M -->|No| C L --> C N --> C style A fill:#e1f5fe style B fill:#f3e5f5 style D fill:#e8f5e8 style E fill:#fff3e0 style F fill:#fce4ec

🔧 Step 1: Create Movement State Variables

First, create these variables for tracking movement states:

    when flag clicked
// Create 'for this sprite only' variables
set [Movement State v] to [random]
set [Target X v] to [0]
set [Target Y v] to [0]
set [Previous X v] to (x position)
set [Previous Y v] to (y position)

🎲 Step 2: Random Movement Detection

Here’s how to implement and detect random movement:

    // Random movement script
when flag clicked
forever
if <(Movement State) = [random]> then
// Store previous position
set [Previous X v] to (x position)
set [Previous Y v] to (y position)

// Random movement
change x by (pick random (-5) to (5))
change y by (pick random (-5) to (5))

// Keep sprite on screen
if <(x position) > [240]> then
set x to [240]
end
if <(x position) < [-240]> then
set x to [-240]
end
if <(y position) > [180]> then
set y to [180]
end
if <(y position) < [-180]> then
set y to [-180]
end

wait (0.1) seconds
end
end

🎯 Step 3: Target Movement System

For moving to specific coordinates:

    // Target movement script
when flag clicked
forever
if <(Movement State) = [target]> then
// Store previous position
set [Previous X v] to (x position)
set [Previous Y v] to (y position)

// Move toward target
if <(distance to x: (Target X) y: (Target Y)) > [5]> then
point towards x: (Target X) y: (Target Y)
move (3) steps
else
// Reached target
set [Movement State v] to [idle]
go to x: (Target X) y: (Target Y)
end

wait (0.05) seconds
end
end

🛑 Step 4: Movement Detection Functions

Create custom blocks to detect movement states:

    // Custom block: Is Moving?
define Is Moving?
if <<not <(x position) = (Previous X)>> or <not <(y position) = (Previous Y)>>> then
set [Is Moving v] to [true]
else
set [Is Moving v] to [false]
end

// Custom block: Is Moving to Target?
define Is Moving to Target?
if <<(Movement State) = [target]> and <(Is Moving) = [true]>> then
set [Moving to Target v] to [true]
else
set [Moving to Target v] to [false]
end

// Custom block: Is Moving Randomly?
define Is Moving Randomly?
if <<(Movement State) = [random]> and <(Is Moving) = [true]>> then
set [Moving Randomly v] to [true]
else
set [Moving Randomly v] to [false]
end

⚡ Step 5: State Change System

Handle state changes with events:

    // Event handler for changing to target movement
when I receive [move to target v]
set [Movement State v] to [target]
set [Target X v] to [0]
set [Target Y v] to [-150]

// Event handler for random movement
when I receive [start random movement v]
set [Movement State v] to [random]

// Event handler for stopping
when I receive [stop movement v]
set [Movement State v] to [idle]

📊 Step 6: Movement Status Display

Optional: Display current movement status:

    when flag clicked
forever
// Update detection
Is Moving?
Is Moving to Target?
Is Moving Randomly?

// Display status (optional)
if <(Movement State) = [random]> then
say [Moving randomly] for (0.1) seconds
else
if <(Movement State) = [target]> then
say (join [Moving to: ] (join (Target X) (join [, ] (Target Y)))) for (0.1) seconds
else
if <(Movement State) = [idle]> then
say [Not moving] for (0.1) seconds
end
end
end
end

This system gives you complete control over movement detection! Each clone can have its own movement state, and you can easily check what type of movement is happening. 🎮

CV

CloneVars_Expert

Replied 45 minutes later

@CodeExplorer_Sam Just to clarify the clone variable concept that was mentioned earlier:

When you create a variable “for this sprite only”, each clone gets its own copy of that variable. This is perfect for your use case! 🎯

    // Each clone can have different values
when I start as a clone
set [Movement State v] to [random] // This clone starts with random movement
set [Clone ID v] to (length of [Clone List v]) // Unique identifier
add (Clone ID) to [Clone List v]

This way, Clone #1 might be moving randomly while Clone #2 is moving to target coordinates, and Clone #3 is idle - all independently! 🚀

CE

CodeExplorer_Sam

Replied 20 minutes later

@SpriteManager_Pro @CloneVars_Expert This is exactly what I needed! 🎉

The “for this sprite only” variables make perfect sense now. I implemented the movement state system and it works beautifully! Each clone can now track its own movement independently.

Thanks for the detailed explanation and code examples! 🙏

VB

Vibelf_Community

Pinned Message • Moderator

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Excellent discussion on movement detection! For those wanting to explore more advanced sprite control concepts:

  • 🎯 Advanced pathfinding algorithms
  • 🤖 AI-driven sprite behaviors
  • 🎮 Complex clone management systems
  • 📊 Performance optimization for many sprites

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