Cross Tab — Algorithm & How to Use It
The Cross tab helps you find a solution for the bottom-face cross. The app analyzes all 6 cross directions (by color) and suggests each move on the 3D cube. You can choose between two modes: Basic and Pro.
Basic vs. Pro — what's the difference?
| Criteria | Basic | Pro |
|---|---|---|
| Goal | Shortest path (QTM) | Easier to execute by hand (ergonomic) |
| Moves | Only R U L F D B face turns | Adds wide r l, M |
| 3D viewer | Shows only the cross + adjacent centers | Shows the full cube |
| Best for | Inspection, counting optimal moves | Practicing speedcubing execution |
The app opens in Basic mode by default. Your choice is saved in the browser — switching tabs or generating a new scramble won't reset the selected tier. When you switch Basic ↔ Pro for the same scramble, the result is taken from the cache (not recomputed from scratch).
Basic algorithm
The engine uses IDA* (Iterative Deepening A*) on the D face with the QTM move set — Quarter Turn Metric: each move is a 90° or 180° face turn.
- Depth limit: up to 8 moves.
- Allows temporarily breaking the cross if that's the shortest path.
- For each cross color, tries 4 cube orientations (y rotations) and picks the one with the fewest moves.
The Cross Direction Analysis table always shows the QTM move count for all 6 colors — even while you're viewing the Pro solution for the currently selected direction. The Min cell is the shortest direction by QTM.
Pro algorithm
Pro still computes QTM as a reference, but prioritizes solutions that are easier to execute:
- Finds more candidates via IDA* with wide moves and M slice turns.
- Scores by ergonomic cost — favoring sexy moves, limiting B turns and cube rotations.
- May pick a sequence slightly longer than QTM if the execution is noticeably smoother.
This is closer to how an experienced speedcuber actually chooses a cross in practice, rather than just counting moves on paper.
6 cross directions & the F face
Each color in the table corresponds to one way of placing the cross on the D face. The solver always orients the cube so the cross color is on D; the F face (the front you'll be solving with) changes depending on the orientation — this is expected behavior, not a bug.
How to read the app's results
- Generate a WCA scramble or paste a move sequence.
- Select the Cross tab.
- Turn on Basic to compare all 6 directions by optimal move count; or Pro to see a practical execution sequence.
- Click a color cell in the table to switch cross directions — the move suggestions update instantly.
- Use Move Suggestions and the 3D viewer to follow each step.