quinticInOut: Symmetric Fifth-Power Motion

Maximum contrast bidirectional motion through mirrored quintic curves

The quinticInOut function creates the most extreme symmetric motion pattern through scaled fifth-power curves. The first half produces extraordinary acceleration while the second half mirrors this with equally extreme deceleration.

$$f(t) = \begin{cases} 16t^5 & \text{if } t < 0.5 \\ -\frac{1}{2}(2t-2)^5 + 1 & \text{if } t \geq 0.5 \end{cases}$$

The scaling factor of 16 maintains continuity while maximizing the quintic acceleration effect, creating the strongest contrast between motion phases possible with polynomial curves.

ライブエディター

const fragment = () => {
  const w = 0.01
  const t = iTime.fract()
  const y = quinticInOut(t)
  const Y = quinticInOut(uv.x)
  const a = vec3(0.2, 0.6, 0.9)
  const b = vec3(0.9, 0.2, 0.6)
  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)
}