Autotile Routing Pipeline — Automatic Tile Transition Selection for 2D Maps

The Problem Imagine a 2D map editor: the user paints with materials — grass, water, sand, stone. At boundaries between them, you need smooth transitions — not just a hard cut "grass | water", but beautiful smooth edges, corners, and corridors. This is what autotiling does — a system that automatically selects the right sprite frame based on the cell's neighborhood. But classic autotiling only handles one transition type (material present / absent). What if you have 10+ materials and not every pair has a dedicated transition spritesheet? How do you visually connect sand to water when you only have sand→dirt and dirt→water ? The Solution: Material Routing The idea: treat materials as nodes in a graph and transition tilesets as edges . Then "how to visually connect two materials" becomes a shortest path problem. The 5-Step Pipeline Step 1 — Tileset Registry What it is. A centralized, immutable index of all available tilesets. Each tileset declares a pair of materials it can render a trans