F-1 Spirit stores its 21 tracks as lists of pieces, and those lists can be rewritten. The editor is an HTML page that reads the ROM, draws each track the way the game draws it and lets you change it: double-click to open, no network needed, and it downloads the patched ROM.
python3 tools/haz_editor.py f1spirit.rom
tools/editor/circuitos.htmlThe page is generated with the ROM and the data inside it (about 800 KB), so once built it works on its own.
The track, in the middle, as a vertical strip: each 32 × 12 tile band is one piece of the sequence, with the start line at the bottom. Below the last one comes the first piece of the next lap, dimmed, with the seam marked.
The minimap, top left, in screen coordinates: the game's marker lives in the top right corner of the screen, and that is where it is drawn. Each leg is coloured by the direction its pieces take —red for left, green for right, cyan for straight— and the red dot marks the piece you are editing.
The panel, with the race, the tables it uses, the byte budget and the warnings.
Click a band of the track, or reach it with the arrow keys, and change it:
| key | what it does |
|---|---|
↑ ↓ | move up and down the track (it wraps around at the end) |
← → | steer the track one column left or right |
+ − | change the piece |
Del | delete the piece |
Home End | jump to the start line or to the end of the lap |
The panel buttons do the same, and add inserting a copy before or after, moving up and down, undo (200 steps) and reverting the whole race.
Steering is what makes the track wind. The shift is added modulo 8 to the column used to read each piece's row of metatiles, and it accumulates from one piece to the next: that is why 0x47 (one column left) and 0x41 (one right) are the two most used values in the ROM. Mind what it does not do: it rotates the row rather than translating it, so the track never wanders off screen, and it does not touch the car —only the three instructions that paint the row ever read that accumulator—.
In SCREEN 2 the pattern table is three banks, one per third of the screen, and the game loads different drawings under the same index in the top one and the bottom one: that is how the track gets its depth. The third selector picks which bank is used; "all three" splits them as they appear on screen.
It is separate data: 21 byte paths in page 6, each byte two signed nibbles that move the marker. Its shape does not come from the sequence —change the shifts and nothing moves here, nor in the game— but its length is tied to it: across all 21 races,
steps = pieces / 2 + 1that is, one step every two pieces. Hence the warning in the panel as soon as you add or remove pieces: the path is left describing something else.
Tick edit the path and the minimap moves to a larger panel where its points can be dragged. Moving one only changes the two legs touching it, so the sum of the deltas stays put and the path still closes, as all 21 in the ROM do. If a leg will not fit in a single step (nibbles reach ±7), the point does not move.
Both areas are full in the original ROM:
| area | where | size | free |
|---|---|---|---|
| the 21 sequences | p07 0x602A–0x7747 | 5917 B | 0 |
| the 21 minimap paths | p06 0xB22E–0xB805 | 1495 B | 0 |
Other data starts right behind each one, so they cannot grow: to add a piece you must remove another, here or in a different race. Making a track one step longer costs 1 byte of path and 4 of sequence. The panel gauge keeps count and, if you go over, the export buttons switch off.
python3 tools/parchea_circuitos.py f1spirit.rom patch.json out.rom
python3 tools/parchea_minimapas.py f1spirit.rom patch.json out.romBoth tools lay the sequences or the paths out back to back from the start of their area and rebuild the pointer table, which is exactly what the editor does. With no changes they return the ROM unchanged, and the project's tests check it —including one that runs the page's own JavaScript and compares its output byte for byte against the tools—.
Every change is saved in the browser by itself and comes back when you reopen the page —the label under the buttons says so—. Even so, the real backup is the file:
Browser storage may not persist when the page is opened from disk, depending on which one you use; the .json does not depend on that. It is the same file that parchea_circuitos.py and parchea_minimapas.py apply.
The editor in the repository has the ROM inside it, so it cannot be shared: that would mean sharing the game. That is what the portable build is for:
python3 tools/haz_editor.py f1spirit.rom --portable
tools/editor/circuitos_portable.htmlIt is 43 KB and holds nothing from the cartridge: on opening it asks you to load your own ROM and pulls the tracks, the graphics and the minimaps out of it in the browser, with nothing uploaded anywhere. That is tools/editor/lector.js, which repeats what tools/exporta_circuitos.py does; a node test checks that both say exactly the same thing.
Edit the pieces themselves (the 3 × 8 metatile grid). When it does, it will have to warn about something: piece tables are shared between races —fifteen of them use the 112-piece one— so touching one changes several tracks at once.