linearInOut: Linear Symmetric Motion

Mathematical Foundation

The linearInOut function maintains the same direct linear interpolation as linearIn, with $f(t) = t$. Linear motion remains constant regardless of acceleration or deceleration phases, resulting in uniform progression.

Live Editor

const fragment = () => {
  const w = 0.01
  const t = iTime.fract()
  const y = linearInOut(t)
  const Y = linearInOut(uv.x)
  const a = vec3(0.1, 0.9, 0.3)
  const b = vec3(0.8, 0.9, 0.7)
  const c = a.mix(b, t).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)
}