Unity shader 之 PhotoShop的色相，饱和度，明度算法实现

效果如下：

代码如下：

float3 RGBToHSV(float3 rgb)
{
   float R = rgb.x;
   float G = rgb.y;
   float B = rgb.z;
   float3 hsv;
   float max1 = max(R, max(G, B));
   float min1 = min(R, min(G, B));

   if (R == max1)
   {
       hsv.x = (G - B) / (max1 - min1);
   }
   if (G == max1)
   {
       hsv.x = 2.0 + (B - R) / (max1 - min1);
   }
   if (B == max1)
   {
       hsv.x = 4.0 + (R - G) / (max1 - min1);
   }

   hsv.x = hsv.x * 60.0;
   if (hsv.x  < 0.0)
   {
       hsv.x = hsv.x + 360.0;
   }
   hsv.z = max1;
   hsv.y = (max1 - min1) / max1;
   return hsv;
}

float3 HSVToRGB(float3 hsv)
{
   float R;
   float G;
   float B;
   if (hsv.y == 0.0)
   {
        R = G = B = hsv.z;
        return float3(R, G, B);
    }

    hsv.x = hsv.x / 60.0;
    int i = int(hsv.x);
    float f = hsv.x - float(i);
    float a = hsv.z * (1.0 - hsv.y);
    float b = hsv.z * (1.0 - hsv.y * f);
    float c = hsv.z * (1.0 - hsv.y * (1.0 - f));
    if (i == 0)
    {
        R = hsv.z;
        G = c;
        B = a;
    }
    else if (i == 1)
    {
        R = b;
        G = hsv.z;
        B = a;
    }
    else if (i == 2)
    {
        R = a;
        G = hsv.z;
        B = c;
    }
    else if (i == 3)
    {
        R = a;
        G = b;
        B = hsv.z;
    }
    else if (i == 4)
    {
        R = c;
        G = a;
        B = hsv.z;
    }
    else
    {
        R = hsv.z;
        G = a;
        B = b;
    }
    return float3(R, G, B);
}

// 根据色相，饱和度，明度，计算染色颜色
half3 ComputeDyeColor(half4 c, half4 dyeValue)
{
    float3 hsv = RGBToHSV(c.rgb);
    hsv.x += dyeValue.x;
    hsv.x = hsv.x % 360;
    hsv.y *= dyeValue.y;
    hsv.z *= dyeValue.z;
    return HSVToRGB(hsv);
}

转载请注明出处：https://www.cnblogs.com/jietian331/p/14379175.html

参考地址：http://imgtec.eetrend.com/d6-imgtec/blog/2016-05/7968.html