// snow
      _SnowDiff("Diffuse/Height", 2D) = "white" {}
      _SnowNormal("NormalSAO", 2D) = "white" {}
      _SnowUpVector("Snow Up Vector", Vector) = (0, 1, 0, 0)
      _SnowTint("Snow Tint Color", Color) = (1,1,1,1)
      _SnowAmount("Amount", Range(0,1)) = 0.5
      _SnowUVScales("UV Scale", Vector) = (50, 50, 0, 0)
      _SnowHeightAngleRange("Height Range", Vector) = (50, 90, 0, 1)   // height range, min/max angle
      // height influence, erosion, crystal, melt
      _SnowParams("Params", Vector) = (0.0, 0.0, 0.3, 0.1)