Resetting

Before this: Buffers

Variables keep their values through presses, players and world loads. Nothing starts over by itself, so most circuits with state need a reset: one input that puts every variable back where it began.

Code
Run
Under the Hood
Use it: a reset that passes on
Modify
Make
Good to Know

button1 Held -> chip red
button2 Held -> chip blue
button3 Held -> chip reset
chip text -> decal Text

Code

@left in red: exec
@left in blue: exec
@left in reset: exec
var redScore: int = 0
var blueScore: int = 0
var lastPoint: string = "none"
@right out text = "Red ${redScore.Value}, Blue ${blueScore.Value} (last: ${lastPoint.Value})"

on red {
  redScore += 1
  lastPoint = "red"
}

on blue {
  blueScore += 1
  lastPoint = "blue"
}

on reset {
  redScore = 0
  blueScore = 0
  lastPoint = "none"
}

A scoreboard for two teams. Each team’s button adds a point and records who scored last. The reset handler writes every variable back to the value it was declared with.

After a few points, what does the sign say right after a reset?

Run

Compile the chip and paste it in-game. Place three Buttons and a brick with a Text Decal.
Wire the Buttons’ Held outputs to red, blue and reset, and text to the Text Decal’s Text.
Score a few points for each team. Press reset: the sign reads “Red 0, Blue 0 (last: none)”, the same as when it was pasted.

Under the Hood

Open the chip. There are three chains, one per handler. The reset chain is three Set Variable gates in a row, each writing a constant, wired from the reset pin.

When you add a variable to a circuit, add it to the reset handler too. A variable left out keeps its old value through every reset, which can look like a bug somewhere else.

Use it: a reset that passes on

A bigger build has several chips, each with its own state. Instead of running a wire from one reset button to every chip, each chip can pass the reset on to the next once it has finished its own. This is a daisy chain.

@left in point: exec
@left in reset: bool
var score: int = 0
var passing: bool = false
@right out text = "Score: ${score.Value}"
@right out resetNext = passing.Value

on point {
  score += 1
}

on reset {
  score = 0
  passing = true
}

on !reset {
  passing = false
}

resetNext turns on after this chip’s reset steps have run, and turns off when the reset button is let go. on !reset runs when reset turns off. It reads the pin’s value, so reset is a bool in this chip. Wired into the next chip’s reset, that rising resetNext starts the next chip’s reset, and so on down the line.

Paste the chip three times. Give each copy its own Button on point and its own Text Decal on text.
Wire a Button’s Held to the first copy’s reset. Wire the first copy’s resetNext to the second copy’s reset, and the second’s resetNext to the third’s reset.
Score a few points on each, then press the reset button. All three signs go back to 0, each one just after the one before it.

Modify

Wire an Attached Zone’s Occupied output to reset instead of the button. The scores clear whenever someone steps into the zone.
Keep a best score that survives a reset. Add var best: int = 0, set it whenever a team’s score passes it, show it on the sign, and leave it out of the reset handler.
Flash a light for two seconds after each reset. Add var flash: bool = false and @right out light = flash.Value, then end the reset handler with:
```
  flash = true
  await Sleep(_, delay = 2.0)
  flash = false
```

Make

Make a round counter chip with @left in reset: exec that counts how many times it has been reset, and shows “Round 3” on a sign. Put it at the end of a chain of two scoreboards, so one button clears the scores and starts a new round.

circuit1 "Scoreboard"
circuit2 "Scoreboard"
chip "Round"
button1 Held -> circuit1 point
button2 Held -> circuit2 point
button3 Held -> circuit1 reset
circuit1 resetNext -> circuit2 reset
circuit2 resetNext -> chip reset
circuit1 text -> decal1 Text
circuit2 text -> decal2 Text
chip text -> decal3 Text

Good to Know

A world save and load keeps every variable, so a circuit starts over only when its reset runs.
A Button’s Held stays on for as long as it is held, but on reset runs once per press. Holding the reset button does not keep resetting.

Next: pick a lesson from the tree on the Learn page.

Wirescript