GreedyTile

Fast pattern synthesis preserving local tile constraints. Safe Rust implementation with CLI and library interfaces.

Examples

Source	Generated	Visualized

Installation and usage

# Install with Rust 1.88.0 or later
cargo install greedytile

# Generate pattern from source image
greedytile input.png

# Process directory of images including rotation, mirroring, and animation
greedytile ./patterns/ -r -m -v

Options

Option	Description	Default	Without Option	With Option
--seed	Seed reproducible generation	42
--iterations	Maximum iterations	1000
--prefill	Use content of <input>_pre.png	disabled
--visualize	Generate placement animation	disabled
--width	Maximum pixel width	unbounded
--height	Maximum pixel height	unbounded
--rotate	Enable 90°/180°/270° tile rotations	disabled
--mirror	Enable tile reflection	disabled
--quiet	Suppress progress output	verbose
--no-skip	Process overwriting existing output	skip existing

Details

GreedyTile generates patterns by placing 3×3 tiles extracted from a source image. Weights for randomly selecting placement are influenced by several factors:

1. Entropy weighting: Prioritizes positions where fewer tile options are valid (similar to WFC)
2. Global balance correction: If pixels are under-represented then selection is biased towards the source balance
3. Distance-based probabilities: Pixel distance patterns in the source are replicated in the output
4. Deadlock recovery: If no choices exist which respect tiles, pixels in a local area are removed before continuing

Commentary

For efficiency, the global balance correction uses a normal distribution to approximate what should technically be a binomial distribution. The approximation becomes accurate at large counts where it matters most.

The distance probability weighting has more impact on easily tiled patterns than complex ones. Restrictive patterns often have less valid tile choices, making the probabilistic selection less relevant.

Limitations

• Fixed tile size: Currently hardcoded to sample 3×3 pixel tiles from the source
• Extensibility: Would be improved by a plugin interface for adding new probability rules