Madison Weaver / Guides

PICO-8 provides two simple way to tell if the user is pressing a button: BTN() and BTNP(). BTN() will return true if the button is currently being pressed, while BTNP() will return true if the button was pressed in the last frame. To tell which button the user is pressing, you pass either a number from 0 to 5 or the glyph that correspond to that button.

On a PICO-8 controller or keyboard input, there are 6 buttons: left, right, up, down, O, and X (O and X are analogous to A and B on other consoles).

To write glyphs into your code, hold Shift and press one of the following keys:

• Left: L
• Right: R
• Down: D
• Up: U
• O: O
• X: X

BTN(0) -- is left pressed
BTN(1) -- is right pressed
BTN(2) -- is up pressed
BTN(3) -- is down pressed
BTN(4) -- is O pressed
BTN(5) -- is X pressed

BTN(⬅️) -- is left pressed
BTN(➡️) -- is right pressed
BTN(⬆️) -- is up pressed
BTN(⬇️) -- is down pressed
BTN(🅾️) -- is O pressed
BTN(❎) -- is X pressed

BTNP(0) -- was left pressed
BTNP(1) -- was right pressed
BTNP(2) -- was up pressed
BTNP(3) -- was down pressed
BTNP(4) -- was O pressed
BTNP(5) -- was X pressed

BTNP(⬅️) -- was left pressed
BTNP(➡️) -- was right pressed
BTNP(⬆️) -- was up pressed
BTNP(⬇️) -- was down pressed
BTNP(🅾️) -- was O pressed
BTNP(❎) -- was X pressed

Here’s an example of how you might use these functions in your game:

RED=8
BLUE=12

FUNCTION _INIT()
  PLAYER_X=64
  PLAYER_COLOR=RED
END

FUNCTION _UPDATE()
  IF BTN(➡️) THEN
    PLAYER_X+=1
  ELSEIF BTN(⬅️) THEN
    PLAYER_X-=1
  END

  IF BTNP(🅾️) THEN
    IF PLAYER_COLOR==RED THEN
      PLAYER_COLOR=BLUE
    ELSE
      PLAYER_COLOR=RED
    END
  END
END

FUNCTION _DRAW()
  CLS()
  CIRCFILL(PLAYER_X,64,4,PLAYER_COLOR)
END