quarticOut: Fourth-Power Deceleration

Inverted quartic curve producing extremely gentle motion completion

The quarticOut function creates dramatic deceleration through inverted fourth-power scaling. This produces rapid initial motion that decelerates to an extremely gentle completion.

$f(t) = -(t-1)^4 + 1$

The inverted quartic relationship amplifies the deceleration effect beyond quadratic and cubic curves, creating extended periods of near-zero velocity toward completion.

ライブエディター

const fragment = () => {
  const w = 0.01
  const t = iTime.fract()
  const y = quarticOut(t)
  const Y = quarticOut(uv.x)
  const a = vec3(0.1, 0.8, 0.9)
  const b = vec3(0.9, 0.4, 0.1)
  const c = a.mix(b, y).mul(uv.x.step(t))
  const lines = mmin2(smoothstep(0, w, uv.mod(0.1).min(uv.sub(vec2(t, y)).abs())))
  const curve = stroke(uv.y.sub(Y), 0, w).mul(c)
  const color = lines.oneMinus().mul(0.2).add(curve)
  return vec4(color, 1)
}