How to detect when a key was just pressed (single keypress detection)
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InputHandler_Sam
Posted on July 20, 2025 • Intermediate
⌨️ HELP! Single keypress detection problem!
I’m working on a game and I need to detect when a key was just pressed - not held down! Here’s my situation:
- I want to detect a single keypress (like jumping or shooting)
- If the player holds the key down, it should NOT keep triggering
- I can’t use wait blocks because they pause my entire game loop
- I need this to work within my main game loop without interruption
Current Problem: When I use “key pressed?” in my forever loop, it keeps triggering while the key is held down. I need it to only trigger ONCE per keypress!
How do I implement proper single keypress detection without breaking my game flow? 🤔
KeyDetection_Expert
Replied 30 minutes later • ⭐ Best Answer
Perfect question @InputHandler_Sam! Single keypress detection is crucial for responsive games. Here are multiple solutions:
🎯 Input Detection System Overview
Here’s how proper keypress detection works:
🔧 Method 1: Single Variable Approach (Simplest)
The easiest solution using just one variable:
// Initialize at start when flag clicked set [Space Key State v] to [0] // Main game loop forever // Check for single keypress if <<key [space v] pressed?> and <(Space Key State) = [0]>> then // Key was just pressed! say [Jump!] for (0.5) seconds // Set state to prevent repeat set [Space Key State v] to [1] end // Reset when key is released if <not <key [space v] pressed?>> then set [Space Key State v] to [0] end // Rest of your game logic here... end
⚡ Method 2: Multi-Key System
Handle multiple keys efficiently:
// Initialize all key states when flag clicked set [Space Pressed v] to [0] set [Enter Pressed v] to [0] set [Up Arrow Pressed v] to [0] // Main input handler forever // Space key detection if <<key [space v] pressed?> and <(Space Pressed) = [0]>> then broadcast [space just pressed v] set [Space Pressed v] to [1] end if <not <key [space v] pressed?>> then set [Space Pressed v] to [0] end // Enter key detection if <<key [enter v] pressed?> and <(Enter Pressed) = [0]>> then broadcast [enter just pressed v] set [Enter Pressed v] to [1] end if <not <key [enter v] pressed?>> then set [Enter Pressed v] to [0] end // Up arrow detection if <<key [up arrow v] pressed?> and <(Up Arrow Pressed) = [0]>> then broadcast [up just pressed v] set [Up Arrow Pressed v] to [1] end if <not <key [up arrow v] pressed?>> then set [Up Arrow Pressed v] to [0] end end
🎮 Method 3: Advanced Input Manager
Professional input handling system:
// Input Manager - runs separately from game loop when flag clicked // Initialize input system set [Input System Active v] to [1] broadcast [start input manager v] // Separate input detection script when I receive [start input manager v] forever if <(Input System Active) = [1]> then // Check all important keys // Jump key (Space) if <<key [space v] pressed?> and <not <(Last Space State) = [1]>>> then broadcast [jump pressed v] end set [Last Space State v] to <key [space v] pressed?> // Attack key (X) if <<key [x v] pressed?> and <not <(Last X State) = [1]>>> then broadcast [attack pressed v] end set [Last X State v] to <key [x v] pressed?> // Menu key (Escape) if <<key [escape v] pressed?> and <not <(Last Escape State) = [1]>>> then broadcast [menu pressed v] end set [Last Escape State v] to <key [escape v] pressed?> end end
🚀 Method 4: Function-Based Approach
Create reusable input detection:
// Custom block: Check Single Keypress define Check Single Keypress (key) (state variable) if <<key (key) pressed?> and <(state variable) = [0]>> then set (state variable) to [1] // Return true (key just pressed) else if <not <key (key) pressed?>> then set (state variable) to [0] end // Return false (key not just pressed) end // Usage in main loop when flag clicked forever // Check for jump Check Single Keypress [space v] [Jump State v] if <(result) = [true]> then // Handle jump change y by [50] end // Check for shoot Check Single Keypress [x v] [Shoot State v] if <(result) = [true]> then // Handle shooting broadcast [fire bullet v] end end
🎯 Method 5: Event-Driven System
Clean separation of input and game logic:
// Input Event System when flag clicked // Input detection (separate from game logic) forever // Detect keypresses and broadcast events if <<key [space v] pressed?> and <(Space State) = [0]>> then broadcast [on space press v] set [Space State v] to [1] end if <not <key [space v] pressed?>> then set [Space State v] to [0] end end // Game logic responds to events when I receive [on space press v] if <(Game State) = [playing]> then // Player jump set [Player Y Velocity v] to [15] play sound [jump v] else if <(Game State) = [menu]> then // Menu selection broadcast [menu select v] end end
🐛 Common Issues & Solutions
- Key still repeating: Make sure you’re checking the previous state correctly
- Missed keypresses: Don’t use wait blocks in your input detection loop
- Laggy response: Keep input detection separate from heavy game logic
- Multiple triggers: Ensure state variables are properly initialized
💡 Pro Tips
- Use broadcasts for clean event-driven architecture
- Keep input detection in a separate forever loop
- Initialize all state variables when the flag is clicked
- Consider using custom blocks for reusable input functions
Choose the method that best fits your game’s complexity! 🎮
InputHandler_Sam
Replied 1 hour later
@KeyDetection_Expert This is exactly what I needed! Thank you! 🎉
I implemented Method 1 first and it works perfectly. No more repeated actions when holding keys down. The event-driven system looks really clean too - I’ll try that for my next project!
Quick question: How do I handle key combinations like Ctrl+Space?
KeyCombo_Master
Replied 45 minutes later
@InputHandler_Sam Great follow-up! For key combinations, use this approach:
// Key combination detection if <<<key [space v] pressed?> and <key [shift v] pressed?>> and <(Combo State) = [0]>> then // Super jump activated! set [Player Y Velocity v] to [25] set [Combo State v] to [1] end // Reset when either key is released if <<not <key [space v] pressed?>> or <not <key [shift v] pressed?>>> then set [Combo State v] to [0] end
This handles combinations while maintaining single-press detection! ⌨️
GameLoop_Optimizer
Replied 30 minutes later
Excellent solutions everyone! One performance tip: if you have many keys to check, consider using a list-based approach:
// Efficient multi-key system when flag clicked // Initialize key list delete all of [Key States v] add [0] to [Key States v] // Space (index 1) add [0] to [Key States v] // Enter (index 2) add [0] to [Key States v] // Up Arrow (index 3) // Key names list delete all of [Key Names v] add [space] to [Key Names v] add [enter] to [Key Names v] add [up arrow] to [Key Names v] // Check all keys efficiently forever set [i v] to [1] repeat (length of [Key Names v]) if <<key (item (i) of [Key Names v]) pressed?> and <(item (i) of [Key States v]) = [0]>> then broadcast (join [key ] (item (i) of [Key Names v])) replace item (i) of [Key States v] with [1] end if <not <key (item (i) of [Key Names v]) pressed?>> then replace item (i) of [Key States v] with [0] end change [i v] by [1] end end
This scales well for games with many input keys! 🚀
Vibelf_Community
Pinned Message • Moderator
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