Scrap Mechanic Blueprint Skill
Quick Start
- Ask user for game install path (usually
D:\SteamLibrary\steamapps\common\Scrap Mechanic\orC:\Program Files (x86)\Steam\steamapps\common\Scrap Mechanic\) - Only modify existing blueprints — never create new UUID. Game can't find new blueprints. User tells you which blueprint name/ID to overwrite.
- Blueprint save path:
%APPDATA%\Axolot Games\Scrap Mechanic\User\User_*\Blueprints\<uuid>\blueprint.json
Parts Database
Load references/parts-database.json for 170+ parts with UUIDs, sizes. Load references/block-types.md for zaxis/bounds rules.
Blueprint JSON Format (v4)
{
"bodies": [{"childs": [...]}],
"joints": [...], // optional
"version": 4
}
Each child: {"color":"HEX","controller":{...},"pos":{"x":x,"y":y,"z":z},"shapeId":"uuid","xaxis":1,"zaxis":-2}
Block Type Differences (CRITICAL)
| Type | zaxis | bounds | stretch |
|---|---|---|---|
Platform connector (295451dd-) |
-2 | optional | no |
| Metal/Wood/Concrete blocks | 3 | required {x,y,z} |
yes |
Never mix zaxis values between types.
controllers (logic wiring)
controllers: [{"id":X}]= this component's output goes TO component Xcontrollers: null= endpoint (light, no forwarding)- IDs start at 1; 0 is reserved
Logic Gate Modes
| mode | gate | behavior |
|---|---|---|
| 0 | AND | all 1→1 |
| 1 | OR | any 1→1 |
| 2 | XOR | exactly one 1→1 |
| 3 | NAND | all 1→0. Single input = NOT gate |
| 4 | NOR | any 1→0 |
Key Rules (Game Verified)
- Signal has NO loss — fan-out is unlimited, no buffers needed
- 1 tick delay per hop — only propagation cost
- Lights only accept ONE input — need OR gate to combine multiple sources
- Blocks must be adjacent — floating blocks split into separate pieces
- Bearing+board+wheel form rigid triangle — can't change relative positions
- Wheels: small d=3+margin*2≈4 effective, spacing ≥4
Vehicle Building (zaxis=-2 orientation)
Board at z=2, xaxis=1, zaxis=-2
Bottom wheels: pos(board_x-1, -1, 4), zaxis=-2
Top wheels: pos(board_x+2, 3, 4), zaxis=2
Bearing joint: posA=posB=(board_x, -2, 2) bottom / (board_x, 3, 2) top
Digital Circuits (Game Verified)
Core Circuits
- 1-tick pulse gen: AND→NAND→AND feedback
- T flip-flop: edge detector(AND+NAND)→XOR↺self
- OR self-latch: OR↺self, 1-tick pulse→permanent ON
- 3-OR ring oscillator: odd ORs = stable oscillator
- Ripple counter: shared 1tick pulse→XOR chain with carry ANDs
- Simplified counter: pulse width < chain length prevents ripple, saves NANDs
Display Decoder
Counter bits → NAND inverters(single input=~X) →
Value-detecting AND gates(one per value) → Pixel-collecting OR gates → Lights
Each light has exactly ONE OR gate as input. OR gate collects from all value-ANDs where pixel should be ON.
Tools
Use scripts/blueprint_builder.py for programmatic blueprint generation. Key API:
- Blueprint(name, version=4) — create blueprint
- .block/shape, x, y, z) — add static block (platform connector)
- .metal(x, y, z, w, h, d) — add metal block with bounds
- .cube/hollow_cube/sphere/cylinder(...) — geometry
- .part/shape, x, y, z, mode, controllers) — interactive component
- .gate/type, x, y, z, inputs) — logic gate shortcut
- .add_wheel(side, body, board_x, board_y) — vehicle wheel with bearing
- .save_to(target_dir) — save to existing blueprint directory
