Fader Footie

Table football (Tischfußball) for two players and a Music Thing 8mu, played in a web page, with the Workshop Computer turning the game into voltages: who touched the ball, where the ball is, every touch and every goal.

The 8mu sits on the table between the two players, its buttons towards the screen. Each player has the four faders nearest them, one for each of their rods, and the two buttons nearest them: a hard and a soft shot, or (if you choose) draw back and shoot.

Status: 0.2.0, beta. The firmware builds and the web page has been tested in Chrome against a simulated card and 8mu, with the CPU playing itself. It has not yet been tried on a Workshop Computer with a real 8mu.

What you need

• A Workshop Computer, plugged into a computer's USB port with a data cable.
• Chrome or Edge on that computer, to open web/index.html.
• An 8mu on its factory settings (faders CC 34-41, buttons notes C2, C3, C4, C5), plugged into the same computer. Without one, the page's on-screen faders and the keyboard work too, and either team can be played by the CPU.

Quick start

1. Copy UF2/fader_footie.uf2 to the card (hold BOOTSEL, plug in, drop the file).
2. Plug the computer into the Computer's front USB socket and power-cycle the module. The card appears as a MIDI device called Fader Footie.
3. Plug the 8mu into the computer.
4. Open web/index.html in Chrome, press Connect card & 8mu, and allow MIDI with SysEx.
5. Team 2 starts as the CPU: set it to Human (next to its score) for two players.

The page plays without a card (no voltages, of course) and without an 8mu.

When it finds an 8mu, the page sends it the same identify message as the Computer's own 8mu driver (EightMU.h). That makes the 8mu load its default setup (faders CC 34-41, buttons C2-C5) and switches off its bank buttons until it is power-cycled, so pressing a top button can never move it to another bank, where its faders would send something else. It also asks where the faders are, so the rods start where the faders sit.

Playing

So the fader nearest each player is their goalie, and the two attacks meet in the middle of the 8mu. Attack nearest the player turns that round, and Swap the two buttons swaps them. A fader pushed up moves its rod up the screen; tick faders upside down for a team if it feels backwards from where that player sits.

The teams are the classic 1-2-5-3: one goalie, two defenders, five midfielders and three attackers, numbered as in football, 1 to 11, top to bottom along each rod. The single goalie can cover the whole width, which leaves the goal open when he goes chasing into a corner.

Buttons. Two ways to play, chosen under Physics (Buttons):

• Hard shot + soft shot (the default, quickest to pick up): the button nearest you spins the rod right round over the bar, the next one flicks it forwards.
• Draw back + shoot, as on a real table: below.

Shooting, as on a real table. The men are moulded plastic players on their rods, seen from above, each with his own skin tone and hair colour (picked at random when the page opens), and they turn the way real ones do:

• Draw back lifts the men's feet up behind them, so they lie face down over the table. Their feet are off the table, so the ball rolls underneath without touching them. They stay drawn back while the button is held, and for a moment after it is let go (Draw-back hold, 0.45s by default, from held only up to 5s).
• Shoot on its own is a soft shot: the men flick their feet forwards, face up at you for a moment, then hang down again.
• Shoot while drawn back is a hard shot: the men swing down through the ball and on, right round over the bar once, to hang down again.

The ball also rolls under the rods themselves. The buttons move the rod nearest the ball, a ball in front counting nearer; Buttons move: all four rods draws back and shoots every rod at once, goalie included, which is more dramatic and leaves the goal open.

Serving. The ball is served from the side of the table at the halfway line, rolling across it. A ball that stops, or rolls around where nobody can reach it, is nudged or served again after a few seconds (Unstick after). A match is first to 5 (or 3, 10, or endless); the next starts by itself.

8mu tilt. Turn up 8mu tilt → slope and tipping the 8mu tips the table.

Keyboard. Team 1 rods Q/A W/S E/D R/F, buttons A and B on Z and X; team 2 rods U/J I/K O/L P/;, buttons C and D on , and .. Space serves, Esc pauses. The on-screen faders and buttons can be dragged and pressed too.

CPU. Either team can be played by the CPU: easy, medium or hard. It draws back for a hard shot when it has the ball at its feet, and medium and hard lift their rods in front out of the way of their own hard shots.

Human + CPU. Each team can also be Human + CPU (easy, medium or hard): the player plays one rod and the CPU plays the other three, to help out. The player's rod is the one whose fader they moved last, and it glows on the table and is outlined under it; moving any other fader takes that rod instead, at any time. (A fader has to move by two steps to take over, so a twitching fader doesn't steal it.) Draw back and shoot work the player's rod. A good way to learn, or to play one against the CPU without four faders to watch. Two CPUs will happily play each other all day, which makes a good generative modulation source with nobody at the table.

Physics

Everything is tweakable while you play, and kept in the browser. Presets: Classic, Ice rink, Pinball, Mud, Beach ball, Marble, Giants, Barn door and Slow motion.

Outputs

Players to CV. The page chooses how a player's number becomes a voltage, and lists all eleven for both teams:

• Notes of a scale (the default, major): player 1 is the root, 2 the next note of the scale, and so on up, 1V/oct. Ten scales.
• Semitones: one semitone per player, 1V/oct.
• Spread 0-5V: player 1 at 0V to player 11 at 5V, for modulation.
• Rods, 1V apart: goalie 0V, defence 1V, midfield 2V, attack 3V.

Player 1 at shifts everything up or down, a semitone at a time, and Team 2 transpose moves team 2 against team 1, so the two teams can play in harmony. The CV outs are calibrated, so they play in tune. Patch them into two oscillators' pitch inputs, the pulse outs into their envelopes, and the game plays a duet.

Distance. Straight-line distance from the goal by default; along the table only ignores the side-to-side position. The page sends it about 60 times a second, and the card smooths it (Main knob). The two audio outs cross over as play moves up and down the table, which is a lovely pair of crossfade or panning voltages. With the switch up they show nearness instead (+5V at the goal), so a voltage rises as an attack builds.

Pulses. A touch is a new contact between the ball and a man; a ball held against a man is one touch. The gate length is set by the X knob. A goal fires a burst of triggers (12 by default, set on the page from 1 to 64) at the rate set by the Y knob, and the burst wins over any touch gates. A gate that is already high goes low for 1ms first, so every touch is a fresh edge.

The card's panel

The page shows the switch and the three knob settings under Outputs.

With no page linked (it pings the card every second), LEDs 4 and 5 blink slowly in turn. The outputs hold their last values.

How it works

The physics runs in the page: a fixed 720Hz step, the ball against the walls, the posts and the men's feet. Each man's feet are a rounded box that moves with its rod and swings forwards and back as the rod turns (so their speed is what kicks the ball), and they only collide while they are near the table. Each man is drawn from his rod's turn: his head, shoulders, arms, legs and boots are boxes in his own frame, each drawn as seen from above, lowest first. The card is a USB MIDI device and does the timing that matters on the jacks: the page sends it the voltages and the touch and goal events as SysEx, and the card makes the gates, bursts and smoothing at the audio rate. The protocol is in sysex.h.

The card is always a USB device, never a host: the game needs the screen, so the 8mu goes into the computer.

Building

cmake -B build -G Ninja
cmake --build build

Needs the Pico SDK. ComputerCard.h is copied from Demonstrations+HelloWorlds/PicoSDK/ComputerCard. The binary is committed at UF2/fader_footie.uf2.

Credits

• Chris Johnson: the ComputerCard library.
• Tom Whitwell / Music Thing Modular: the Workshop System and the 8mu.

Written with Claude (Anthropic) in collaboration with the card's author.

License

MIT.