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

效果如下：

代码如下：

 1 float3 RGBToHSV(float3 rgb)
 2 {
 3    float R = rgb.x;
 4    float G = rgb.y;
 5    float B = rgb.z;
 6    float3 hsv;
 7    float max1 = max(R, max(G, B));
 8    float min1 = min(R, min(G, B));
 9 
10    if (R == max1)
11    {
12        hsv.x = (G - B) / (max1 - min1);
13    }
14    if (G == max1)
15    {
16        hsv.x = 2.0 + (B - R) / (max1 - min1);
17    }
18    if (B == max1)
19    {
20        hsv.x = 4.0 + (R - G) / (max1 - min1);
21    }
22 
23    hsv.x = hsv.x * 60.0;
24    if (hsv.x  < 0.0)
25    {
26        hsv.x = hsv.x + 360.0;
27    }
28    hsv.z = max1;
29    hsv.y = (max1 - min1) / max1;
30    return hsv;
31 }
32 
33 float3 HSVToRGB(float3 hsv)
34 {
35    float R;
36    float G;
37    float B;
38    if (hsv.y == 0.0)
39    {
40         R = G = B = hsv.z;
41         return float3(R, G, B);
42     }
43 
44     hsv.x = hsv.x / 60.0;
45     int i = int(hsv.x);
46     float f = hsv.x - float(i);
47     float a = hsv.z * (1.0 - hsv.y);
48     float b = hsv.z * (1.0 - hsv.y * f);
49     float c = hsv.z * (1.0 - hsv.y * (1.0 - f));
50     if (i == 0)
51     {
52         R = hsv.z;
53         G = c;
54         B = a;
55     }
56     else if (i == 1)
57     {
58         R = b;
59         G = hsv.z;
60         B = a;
61     }
62     else if (i == 2)
63     {
64         R = a;
65         G = hsv.z;
66         B = c;
67     }
68     else if (i == 3)
69     {
70         R = a;
71         G = b;
72         B = hsv.z;
73     }
74     else if (i == 4)
75     {
76         R = c;
77         G = a;
78         B = hsv.z;
79     }
80     else
81     {
82         R = hsv.z;
83         G = a;
84         B = b;
85     }
86     return float3(R, G, B);
87 }
88 
89 // 根据色相，饱和度，明度，计算染色颜色
90 half3 ComputeDyeColor(half4 c, half4 dyeValue)
91 {
92     float3 hsv = RGBToHSV(c.rgb);
93     hsv.x += dyeValue.x;
94     hsv.x = hsv.x % 360;
95     hsv.y *= dyeValue.y;
96     hsv.z *= dyeValue.z;
97     return HSVToRGB(hsv);
98 }

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