Simple, procedural mountain landscape view with Jetpack Compose

BackgroundView.kt

/* Copyright 2020 Google LLC.
   SPDX-License-Identifier: Apache-2.0 */

@Composable
fun BackgroundView(
  speed: Float = 0.3f,
  peakDensity: Float = .5f,
  sunOffset: Float = 0.4f,
  sunColor: Color = Color.White,
  startColor: Color = Color.DarkGray,
  endColor: Color = Color.LightGray,
  steps: Int = 12,
  modifier: Modifier
) {
  var time: Long by remember { mutableStateOf(0L) }
  LaunchedEffect(true) {
    while (isActive) {
      withFrameMillis { time = it }
    }
  }

  Canvas(modifier = modifier) {
    drawCircle(color = sunColor, center = Offset(x = center.x, y = size.height * sunOffset))

    val path = Path()
    (0..steps).forEach { index ->
      val parallax2 = log(x = 2 + index.toDouble(), base = steps + 1.0).toFloat()
      val parallax3 = log(x = 3 + index.toDouble(), base = steps + 1.0).toFloat()
      val waveWidth = (size.width / peakDensity * parallax3).toInt()

      path.reset()
      (0..(size.width.toInt() + waveWidth * 4) step waveWidth).forEachIndexed { peakIndex, offset ->
        path.lineTo(
          x = offset.toFloat() - (time * parallax2 * speed) % waveWidth * 2,
          y = size.height / 1f * if (peakIndex % 2 == 0) parallax2 else parallax3
        )
      }

      path.lineTo(size.width, size.height)
      path.lineTo(0f, size.height)
      path.close()

      val parallax1 = log(x = 1 + index.toDouble(), base = steps + 1.0).toFloat()
      val color = lerp(startColor, endColor, parallax1)
      drawPath(path = path, color = color)
    }
  }
}