Procedural 2D Sprites & Pixel Art

Generate 2D pixel art assets for ZX games: sprites, UI elements, tilesets, and sprite sheets.

Output Requirements

• Format: PNG (RGBA or indexed)
• Color: Indexed palettes (4-256 colors) or full RGBA
• Compatible with: draw_sprite(), draw_sprite_region()

Quick Decision Guide

Need	Algorithm	Reference
Reduce colors	Median cut	references/palette-algorithms.md
Smooth gradients	Floyd-Steinberg	references/dithering-patterns.md
Retro look	Bayer ordered dither	references/dithering-patterns.md
Scalable panels	9-slice	references/ui-sprites.md
Auto-connecting terrain	Autotile (16/47/256)	references/tileset-generation.md
Character animations	Sprite sheets	references/sprite-organization.md

Common Sprite Sizes

Type	Size	Notes
UI icon	16x16, 32x32	Power of 2
Character	32x32, 64x64	4-8 directions, 3-4 frames
Tile	16x16, 32x32	Must tile seamlessly
Health bar	64x8, 128x12	Segmented or continuous

Autotile Systems

System	Tiles	Complexity	Use Case
2-corner	16	Simple	Basic terrain
4-corner	47	Medium	Standard RPG
Blob	256	Complex	Smooth transitions

Basic Palette Quantization

from PIL import Image

def quantize_image(path, num_colors=16):
    """Quick palette extraction."""
    img = Image.open(path).convert('RGB')
    return img.quantize(colors=num_colors, method=Image.Quantize.MEDIANCUT)

For detailed algorithms, see references/palette-algorithms.md.

Basic Dithering

def apply_bayer_dither(img, palette):
    """Ordered dithering for retro look."""
    bayer = [[0,8,2,10], [12,4,14,6], [3,11,1,9], [15,7,13,5]]
    # Apply threshold matrix before quantizing
    # See references/dithering-patterns.md for full implementation

ZX Integration

# nether.toml
[[assets.textures]]
id = "ui-sprites"
path = "generated/textures/ui_elements.png"
filter = "nearest"  # Critical for pixel art

// Drawing sprites
draw_sprite(sprites, x, y);

// Drawing from sprite sheet (e.g., button state 2)
draw_sprite_region(sprites, x, y, state * width, 0, width, height);

File Organization

Author sprite sheets as texture specs under .studio/specs/textures/ and generate with:

python .studio/generate.py --only textures

References

• references/palette-algorithms.md - Median cut, k-means, quantization
• references/dithering-patterns.md - Bayer, Floyd-Steinberg, error diffusion
• references/ui-sprites.md - 9-slice, health bars, buttons
• references/tileset-generation.md - Autotiles, variations, animated tiles
• references/sprite-organization.md - Sprite sheets, palette swaps

Related Skills

• procedural-textures - Noise algorithms for sprite bases
• semantic-asset-language - Style tokens for sprite generation