Preventing noclip and collision bugs in Scratch games
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CollisionExpert_Dev
Posted on January 26, 2024 • Advanced
🚫 Noclip collision detection issues
I’m developing a platformer game and I’m having persistent issues with collision detection. My basic collision system works most of the time, but players can still occasionally clip through walls, especially when moving fast or at certain angles.
Problems I’m experiencing:
- Players sometimes pass through solid walls
- Fast movement causes collision detection to fail
- Corner cases where collision isn’t detected properly
- Inconsistent behavior with different sprite sizes
I know this is a common issue in game development, but I need a bulletproof collision system that prevents all forms of noclipping. Any help with creating robust collision detection would be incredibly valuable! 🛡️
PhysicsSystem_Master
Replied 45 minutes later • ⭐ Best Answer
Excellent question @CollisionExpert_Dev! Noclipping is indeed one of the most challenging aspects of game physics. I’ll show you how to build a bulletproof collision system that prevents all forms of wall clipping!
🔍 Understanding Noclip Causes
Here’s why basic collision detection fails:
🛡️ Bulletproof Collision System
Here’s a robust collision detection system that prevents all noclipping:
// Advanced collision detection system define move with collision (dx) (dy) // Store current position set [old x v] to (x position) set [old y v] to (y position) // Calculate target position set [target x v] to ((x position) + (dx)) set [target y v] to ((y position) + (dy)) // Step-by-step movement (prevents tunneling) set [steps v] to (round ((sqrt (((dx) * (dx)) + ((dy) * (dy)))) / [2])) if <(steps) < [1]> then set [steps v] to [1] end set [step x v] to ((dx) / (steps)) set [step y v] to ((dy) / (steps)) // Move in small increments repeat (steps) change x by (step x) change y by (step y) // Check collision after each step if <touching [Walls v]?> then // Collision detected - revert and stop set x to (old x) set y to (old y) stop [this script v] end // Update old position for next iteration set [old x v] to (x position) set [old y v] to (y position) end
🎯 Axis-Separated Collision
Handle X and Y movement separately for better control:
// Separate X and Y collision handling define move with separated collision (dx) (dy) // Handle X movement first if <not <(dx) = [0]>> then move with collision on axis [x] by (dx) end // Then handle Y movement if <not <(dy) = [0]>> then move with collision on axis [y] by (dy) end define move with collision on axis (axis) by (distance) set [old position v] to (x position) if <(axis) = [y]> then set [old position v] to (y position) end // Calculate step size (smaller = more accurate) set [step size v] to [1] if <(distance) < [0]> then set [step size v] to [-1] end set [remaining distance v] to (abs (distance)) repeat until <(remaining distance) = [0]> // Move one step if <(axis) = [x]> then change x by (step size) else change y by (step size) end // Check for collision if <touching [Walls v]?> then // Revert the step if <(axis) = [x]> then change x by ((step size) * [-1]) else change y by ((step size) * [-1]) end stop [this script v] end change [remaining distance v] by [-1] end
🔧 Advanced Collision Features
Add sophisticated collision behaviors:
// Sliding collision (smooth wall interaction) define move with sliding collision (dx) (dy) // Try full movement first move with collision (dx) (dy) // If blocked, try sliding along walls if <touching [Walls v]?> then // Reset position set x to (old x) set y to (old y) // Try X movement only (slide along Y-axis) move with collision (dx) (0) // If X worked, try Y movement if <not <touching [Walls v]?>> then move with collision (0) (dy) else // Reset and try Y movement only set x to (old x) set y to (old y) move with collision (0) (dy) end end // Push-out system (escape from inside walls) define push out of walls set [push attempts v] to [0] repeat until <not <touching [Walls v]?>> // Try pushing in all directions change x by [1] if <not <touching [Walls v]?>> then stop [this script v] end change x by [-2] if <not <touching [Walls v]?>> then stop [this script v] end change x by [1] change y by [1] if <not <touching [Walls v]?>> then stop [this script v] end change y by [-2] if <not <touching [Walls v]?>> then stop [this script v] end change y by [1] change [push attempts v] by [1] if <(push attempts) > [20]> then // Emergency teleport to safe position go to x: [0] y: [0] stop [this script v] end end
⚡ High-Speed Movement Protection
Handle fast movement without tunneling:
// Raycast collision detection define raycast from (start x) (start y) to (end x) (end y) set [ray distance v] to (sqrt (((end x) - (start x)) ^ 2 + ((end y) - (start y)) ^ 2)) set [ray steps v] to (round ((ray distance) / [2])) if <(ray steps) < [1]> then set [ray steps v] to [1] end set [ray step x v] to (((end x) - (start x)) / (ray steps)) set [ray step y v] to (((end y) - (start y)) / (ray steps)) set [ray x v] to (start x) set [ray y v] to (start y) repeat (ray steps) change [ray x v] by (ray step x) change [ray y v] by (ray step y) // Check collision at this point go to x: (ray x) y: (ray y) if <touching [Walls v]?> then // Collision found - move to previous safe position change [ray x v] by ((ray step x) * [-1]) change [ray y v] by ((ray step y) * [-1]) go to x: (ray x) y: (ray y) set [collision detected v] to [true] stop [this script v] end end set [collision detected v] to [false] // Usage in movement define move with raycast (dx) (dy) raycast from (x position) (y position) to ((x position) + (dx)) ((y position) + (dy)) if <(collision detected) = [false]> then change x by (dx) change y by (dy) end
🎮 Complete Movement System
Put it all together in a professional movement controller:
// Main movement controller when flag clicked set [movement speed v] to [5] set [collision precision v] to [1] // Lower = more accurate forever set [dx v] to [0] set [dy v] to [0] // Get input if <key [right arrow v] pressed?> then change [dx v] by (movement speed) end if <key [left arrow v] pressed?> then change [dx v] by ((movement speed) * [-1]) end if <key [up arrow v] pressed?> then change [dy v] by (movement speed) end if <key [down arrow v] pressed?> then change [dy v] by ((movement speed) * [-1]) end // Apply movement with collision if <not <((dx) = [0]) and ((dy) = [0])>> then move with sliding collision (dx) (dy) end // Safety check - push out if somehow inside wall if <touching [Walls v]?> then push out of walls end end
This system creates absolutely bulletproof collision detection that prevents all noclipping! 🛡️✨
CollisionExpert_Dev
Replied 1 hour later
@PhysicsSystem_Master This is absolutely incredible! 🤯 The step-by-step movement and raycast system completely eliminated all noclipping issues!
My platformer now has rock-solid collision detection. Players can’t clip through walls no matter how fast they move or what angles they approach from. The sliding collision makes movement feel natural too. Thank you for this comprehensive solution!
GameEngine_Pro
Replied 3 hours later
Fantastic collision system! Here are some additional optimization tips for performance:
- Spatial partitioning: Only check collision with nearby walls
- Collision layers: Separate different types of collision objects
- Adaptive precision: Use higher precision only when needed
- Collision caching: Remember recent collision results
These techniques can make your collision system both bulletproof AND performant! ⚡
Vibelf_Community
Pinned Message • Moderator
🚀 Master Professional Game Physics
Outstanding discussion on collision systems! For developers looking to create professional-grade physics and collision systems, our community can help you implement:
- 🛡️ Advanced collision detection algorithms
- ⚡ High-performance physics optimization
- 🎮 Professional game feel and polish
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📚 Related Physics Topics
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