Pick the right fence or wall piece so lines, corners and crossings join up

Players place wall pieces one at a time and expect them to turn into corners, ends and crossings by themselves. Here is a compact way to choose the picture for each piece from its neighbours, and which pieces need to be redrawn when one is placed or removed.

Why this works

Each piece only needs to know which of its four sides has a partner, and that small yes-or-no per side already names its picture. A change can only reach its direct neighbours, so redrawing just those keeps big bases fast and the pieces always matching.

When not to use it

Not enough for walls that need corners cut at other angles, diagonal fences, or pieces whose look depends on more than touching sides, like height or material. Then use a richer set of neighbours, or hand-drawn pieces placed by the builder.

In the full entry

• What to build, step by step
• Starting values and the reason for each
• 4 common mistakes and the fix
• A diagram of every state
• 21 lines of example code with 4 checks that pass
• How your AI shows you that it works

Say this to your AI

Use the Spielerando entry "Pick the right fence or wall piece so lines, corners and crossings join up" (read_entry survival-fence-pieces-join-neighbours) in my game. Build it step by step, and show me how you checked that it works.

Or skip this and connect the MCP: your AI then finds all of this by itself.Connect the MCP