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Need Help Detecting Which ID the Player Collides With

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CZ

CollisionDetector_Z

Posted on July 17, 2025 • Intermediate

🎯 Collision ID detection challenge

Hi everyone! I’m working on a project where I need to detect which specific object the player collides with, not just that a collision happened.

My setup:

  • Multiple objects/clones in the game world
  • Each object has a unique ID or identifier
  • Player has a hitbox sprite for collision detection
  • Need to know exactly which object was hit

The basic collision detection works fine - I can detect when the player touches something. But I can’t figure out how to identify which specific object was touched when there are multiple objects of the same type.

For example, if I have 10 enemy clones, how do I know which enemy clone the player collided with? I need this for things like:

  • Removing specific enemies when hit
  • Triggering different effects based on object type
  • Tracking which collectibles have been picked up

Any ideas on how to implement this kind of collision ID system? 🤔

CS

CollisionSystemExpert

Replied 3 hours later • ⭐ Best Answer

Great question @CollisionDetector_Z! This is a common challenge when building complex games with multiple interactive objects. There are several effective approaches to solve this!

🧠 Understanding the Problem

The core issue is that Scratch’s basic collision detection only tells you IF a collision happened, not WITH WHAT. We need to create a system that can identify specific objects.

flowchart TD A[🏃 Player moves] --> B[Collision detected] B --> C{Which approach?} C -->|Method 1| D[Clone ID System] C -->|Method 2| E[Position-Based Detection] C -->|Method 3| F[Broadcast System] D --> G[Each clone has unique ID] E --> H[Check object positions] F --> I[Objects report themselves] G --> J[✅ Know exact clone] H --> J I --> J style A fill:#e1f5fe style J fill:#e8f5e8 style C fill:#fff3e0

🎯 Method 1: Clone ID System (Recommended)

This is the most reliable approach for clone-based objects:

    // In the main sprite (before creating clones)
when flag clicked
set [next clone id v] to [1]
set [collision detected id v] to [0]

// When creating each clone
when I receive [create enemy v]
create clone of [Enemy v]
change [next clone id v] by (1)

// In the Enemy sprite
when I start as a clone
set [my id v] to (next clone id)

forever
if <touching [Player Hitbox v] ?> then
set [collision detected id v] to (my id)
broadcast [collision with enemy v]
end
end

🔍 Method 2: Advanced Position-Based Detection

For when you need to identify objects by their location:

    // In the Player Hitbox sprite
define check collision details
set [collision id v] to [0]
set [collision type v] to []

// Check each possible collision type
if <touching [Enemies v] ?> then
set [collision type v] to [enemy]
find closest enemy id
end

if <touching [Collectibles v] ?> then
set [collision type v] to [collectible]
find closest collectible id
end

define find closest enemy id
set [closest distance v] to [999999]
set [closest id v] to [0]

// Check all enemy clones
broadcast [report positions v]
wait (0.1) seconds // Let all clones report

// This requires each clone to report its position and ID
// when it receives the broadcast

🚀 Method 3: Smart Broadcast System

Let the objects identify themselves when touched:

    // In each object sprite (Enemy, Collectible, etc.)
when I start as a clone
set [my id v] to (next clone id)
set [my type v] to [enemy] // or whatever type this is

forever
if <touching [Player Hitbox v] ?> then
// Report collision with specific details
set [last collision id v] to (my id)
set [last collision type v] to (my type)
set [last collision x v] to (x position)
set [last collision y v] to (y position)

broadcast [collision detected v]

// Prevent multiple reports from same collision
wait (0.1) seconds
end
end

⚡ Method 4: Complete Collision Management System

Here’s a comprehensive solution that handles multiple object types:

    // Global collision manager (in Stage or main sprite)
when flag clicked
set [collision queue v] to []
set [processing collision v] to [false]

when I receive [collision detected v]
if <(processing collision) = [false]> then
set [processing collision v] to [true]

// Process the collision based on type
if <(last collision type) = [enemy]> then
handle enemy collision (last collision id)
end

if <(last collision type) = [collectible]> then
handle collectible collision (last collision id)
end

if <(last collision type) = [powerup]> then
handle powerup collision (last collision id)
end

set [processing collision v] to [false]
end

define handle enemy collision (id)
// Find and affect the specific enemy
broadcast [enemy hit v] and wait
// The enemy with matching ID will respond

define handle collectible collision (id)
// Remove specific collectible and update score
broadcast [collectible taken v] and wait
change [score v] by (10)

🎮 Method 5: Object-Specific Response System

Make each object handle its own collision response:

    // In Enemy sprite
when I receive [enemy hit v]
if <(my id) = (last collision id)> then
// This enemy was hit!
change [enemy health v] by (-1)

if <(enemy health) < [1]> then
// Create death effect
create clone of [Explosion v]
delete this clone
else
// Show damage effect
set [color effect v] to (50)
wait (0.2) seconds
set [color effect v] to (0)
end
end

// In Collectible sprite  
when I receive [collectible taken v]
if <(my id) = (last collision id)> then
// This collectible was taken!
play sound [pickup v]
create clone of [Sparkle Effect v]
delete this clone
end

🔧 Bonus: Multi-Layer Collision Detection

For complex games with multiple collision layers:

    define advanced collision check
// Check different collision layers
set [ground collision v] to [false]
set [enemy collision v] to [false]
set [item collision v] to [false]

// Layer 1: Ground/Walls
if <touching color (#8B4513) ?> then // Brown for ground
set [ground collision v] to [true]
end

// Layer 2: Enemies (check each enemy type)
if <touching color (#FF0000) ?> then // Red for enemies
set [enemy collision v] to [true]
find specific enemy
end

// Layer 3: Items/Collectibles
if <touching color (#FFD700) ?> then // Gold for items
set [item collision v] to [true]
find specific item
end

define find specific enemy
// Use color detection + position to identify exact enemy
set [check x v] to (x position)
set [check y v] to (y position)

broadcast [enemy position check v]
wait (0.1) seconds

// Enemies report if they're at the collision point

💡 Pro Tips for Collision ID Systems

  • Unique IDs: Always ensure each clone gets a unique identifier
  • Collision cooldown: Add small delays to prevent multiple collision reports
  • Performance: Use broadcasts efficiently - don’t check collisions every frame for every object
  • Debugging: Create visual indicators to show which object was hit during development
  • Cleanup: Remove collision data when objects are deleted

The clone ID system (Method 1) is usually the best approach for most games. It’s reliable, efficient, and easy to debug! 🎯

CZ

CollisionDetector_Z

Replied 1 hour later

@CollisionSystemExpert This is exactly what I needed! 🤩 The clone ID system is perfect for my project!

I implemented Method 1 and it works flawlessly - now I can tell exactly which enemy was hit and remove just that specific clone. The collision cooldown tip was crucial too, it prevented the weird double-collision bugs I was getting.

The broadcast system approach is really clever too - I’m planning to use that for my more complex interactions. Thanks for the comprehensive breakdown! 🎉

GD

GameDev_Pro

Replied 2 hours later

Excellent solution @CollisionSystemExpert! 👏 I’d like to add one more technique that’s super useful for RPG-style games:

Object Property Detection: You can also store additional data with each collision:

    // Store object properties when collision happens
when I start as a clone
set [my damage v] to (random (5) (15))
set [my type v] to [fire enemy]
set [my level v] to (3)

if <touching [Player v] ?> then
set [collision damage v] to (my damage)
set [collision element v] to (my type)
set [collision level v] to (my level)
broadcast [detailed collision v]
end

This lets you create rich interaction systems where different objects have different properties! 🎮

VB

Vibelf_Community

Pinned Message • Moderator

🎯 Master Advanced Collision Detection Systems

Excellent discussion on collision ID detection! For developers ready to build sophisticated collision systems and object management, our expert tutors can help you master:

  • 🎯 Advanced collision detection and object identification
  • 🔧 Clone management and ID systems
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