Math.inverse_lerp

Math.inverse_lerp(a, b, v) -> fixed

The inverse of Math.lerp: given endpoints a and b and a value v, it returns the fraction (v - a) / (b - a) — 0.0 when v equals a, 1.0 when it equals b. Use it to turn a raw quantity into a normalized amount: how full a health bar is, how far a timer has run, or the t to feed into another Math.lerp. The endpoints must differ, since equal ones would divide by zero.

Parameters

athe endpoint that maps to 0.0

bthe endpoint that maps to 1.0

vthe value to locate between them

Example

program HealthFraction {
  const MAX_HP: fixed = 200.0

  var hp: fixed = 150.0

  handler Draw phase Render {
    let fraction = Math.inverse_lerp(0.0, MAX_HP, hp)   # 0.75
  }
}

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