Day 012 — Error Line

Fullscreen spray paint canvas. Pick a cap, choose a color, and tag the entire browser window.

Desktop first. Not optimized for mobile.

Features

• 5 cap types — Skinny, Standard, Fat Cap, Super Fat, Clogged (asymmetric splatter)
• Pressure — 1–6 bar, affects paint density and drip threshold
• Distance — 3–40 cm, controls spot size and edge softness
• Opacity — 20–100%, global alpha multiplier
• Sharpness — 0–100%, hard edge vs. soft glow falloff
• Paint drips — accumulation-based, gravity-driven with bulge heads
• Undo/Redo — per stroke (mousedown→mouseup), Ctrl+Z / Ctrl+Y, up to 40 steps
• Resize-safe — canvas content preserved on window resize

Controls

Input	Effect
Mouse drag	Spray paint
Cap buttons	Switch nozzle type
Color dots	Switch paint color
Sliders	Pressure, distance, opacity, sharpness
Ctrl+Z	Undo last stroke
Ctrl+Y / Ctrl+Shift+Z	Redo
Clear	Wipe canvas (undoable)

Stack

Single-file HTML/JS, no dependencies. Canvas 2D with radial gradients and per-frame particle rendering.