Advanced Scratch Programming Guide

Variables and lists are key to advanced projects:

• Use lists as arrays for storing game data (e.g., enemy health, positions).
• Simulate multi-dimensional arrays by having one list store references to others.
• Keep “global” variables for shared state and “local” variables for temporary use.
• Optimize by reusing lists instead of creating new ones mid-project.

Example: Use two lists X_Positions and Y_Positions to track dozens of objects without creating separate sprites.

Broadcasting lets you decouple your scripts:

• Use broadcast and wait when you need scripts to run in sequence.
• Create “event channels” (like GameStart, NextLevel, GameOver).
• Chain broadcasts for state machines (menus → gameplay → results screen).

Cloning allows you to simulate object-oriented behavior:

• Create bullet systems by cloning one sprite multiple times.
• Give each clone unique properties by storing their data in lists indexed by my clone ID.
• Limit clones with conditions to prevent lag (e.g., max 300 clones).

Advanced tip: use a “clone pool” — recycle clones instead of deleting and creating new ones.

Custom blocks (functions) make code reusable and clean:

• Use parameters for flexible behaviors (e.g., “moveTo(x, y)”).
• Enable “Run without screen refresh” for faster calculations.
• Build your own math, physics, or AI helper blocks.

Scratch doesn’t have arrays or objects, but you can simulate them:

• Use parallel lists (IDs, positions, health, etc.).
• Serialize complex data as text (e.g., “10,20,30” split into values).
• Build lookup tables for speed (store precalculated values in lists).

• Enemy AI: use sensing blocks to detect distance/angle to the player.
• Pathfinding: approximate with grid maps stored in lists.
• Physics: simulate gravity with velocity variables and floor detection.
• Collision detection: compare distances or use overlapping costume checks.

Big projects often lag — here’s how to optimize:

• Reduce forever loops. Use broadcasts or timers where possible.
• Group code into fewer scripts that handle multiple objects at once.
• Turn off “draggable” on sprites unless needed.
• Hide calculations inside custom blocks with “run without screen refresh.”

• Use pen extension for drawing shapes, graphs, or dynamic UIs.
• Implement raycasting for pseudo-3D effects.
• Preload assets in costumes for faster switching.

TurboWarp extends Scratch capabilities:

• Run projects at 60fps for smooth visuals.
• Use JavaScript extensions to add new blocks.
• Export as HTML/ZIP to share projects outside Scratch.
• Enable compiler settings for 10x faster performance.

Large projects require careful planning:

• Separate code into “systems” (input, AI, rendering, sound).
• Keep naming consistent for variables and lists.
• Document code by adding comments to scripts.
• Prototype small features before merging into the main project.