button-delta ( old? new? -- delta )
Game controller input

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Next:	buttons-delta ( old-buttons new-buttons -- delta )

Vocabulary
game.input

Inputs

old?	a boolean
new?	a boolean

Outputs

delta

pressed, released, or f

Word description
Outputs a symbol representing the change in a key or button's state given a "before" and "after" sample of its state. Outputs pressed if old? is false and new? is true, released if old? is true and new? is false, or f if the two inputs have the same boolean value.

See also
buttons-delta, buttons-delta-as

Definition

USING: combinators kernel ;

IN: game.input

: button-delta ( old? new? -- delta )
    {
        { [ 2dup xor not ] [ 2drop f ] }
        { [ dup not ] [ 2drop released ] }
        { [ over not ] [ 2drop pressed ] }
    } cond ; inline