0xheycat Autotiling & Edge Transitions
Overview
Hard edges between grass and water look like a checkerboard. Autotiling picks the correct edge/corner transition tile based on a bitmask of neighbors. This skill defines the transition set and the bitmask rule.
When to Use
- Two terrain types meet and the seam looks harsh.
- You want maps to look hand-blended without hand-placing every edge.
- You need a repeatable rule for which transition tile to use.
Process
- Define the base terrains and their priority order (e.g. water < sand < grass).
- Author the 16-tile (or 47-tile) transition set for each terrain pair.
- For each cell, compute a neighbor bitmask (N, E, S, W and corners).
- Map the bitmask to the correct transition tile index.
- Render the transition tile on top of the lower-priority base.
- Verify all 16 bitmask cases visually with a test map.
- Cache the bitmask->tile lookup for performance.
bitmask = N*1 + E*2 + S*4 + W*8 -> transitionTile[bitmask]
Rationalizations (Stop Lying to Yourself)
| Excuse | Reality |
|---|---|
| "I will hand-place edge tiles" | Hundreds of edges by hand is unmaintainable. Use a bitmask rule. |
| "One generic edge tile is enough" | Corners need their own tiles or you get gaps. Author the full set. |
Red Flags - STOP if you catch yourself:
- Hard checkerboard seams between terrains.
- Missing corner transition tiles.
- Bitmask computed but never cached (slow).
Verification
You are NOT done until every box is checked:
- A complete transition set exists per terrain pair.
- All bitmask cases render correctly on a test map.
- The bitmask->tile lookup is cached.