RGBHSV 转换

fixed3 RGBtoHSV(fixed3 c)
{
  fixed4 K = fixed4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
  fixed4 p = lerp(fixed4(c.bg, K.wz), fixed4(c.gb, K.xy), step(c.b, c.g));
  fixed4 q = lerp(fixed4(p.xyw, c.r), fixed4(c.r, p.yzx), step(p.x, c.r));

  float d = q.x - min(q.w, q.y);
  float e = 1.0e-10;
  return fixed3(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x);
}

fixed3 HSVtoRGB(fixed3 c)
{
  fixed4 K = fixed4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
  fixed3 p = abs(frac(c.xxx + K.xyz) * 6.0 - K.www);
  return c.z * lerp(K.xxx, saturate(p - K.xxx), c.y);
}

posted @ 2017-09-29 13:23  StraussDu  阅读(70)  评论(0编辑  收藏