OpenGL马赛克（八-2）
作者：互联网
上一节写了如何实现全部马赛克
本篇做的是部分马赛克：
需要理解的点：片元着色器，每一个片元（像素）执行一次片元着色器的程序；所以你在片元着色器中写的程序都是针对逐个像素的；
片元着色器代码：（本博客直接修改原图显示的像素，未进行图片叠加，融合，等马赛克方式）
1 #version 330 core
2 layout(location = 0) out vec4 FragColor;
3 in vec2 TexCoord;
4 uniform sampler2D dataY;
5 uniform sampler2D dataU;
6 uniform sampler2D dataV;
7 vec3 yuv;
8 vec3 rgb;
9 //马赛克块大小
10 const vec2 mosaicSize = vec2(30.0, 30.0);
11 //图片大小
12 const vec2 TexSize = vec2(1920.0, 1080.0);
13
14 void main()
15 {
16 //计算实际图像位置 换算成1920*1080的坐标
17 vec2 intXY = vec2(TexCoord.x * TexSize.x, TexCoord.y * TexSize.y);
18 //部分马赛克
19 if( TexCoord.x > 0.3 && TexCoord.x <0.6 && TexCoord.y > 0.3 && TexCoord.y< 0.6)
20 {
21 //floor(x)返回⼩于等于X的最⼤整数值.计算出整数个马赛克的坐标
22 vec2 XYMosaic = vec2(floor(intXY.x / mosaicSize.x) * mosaicSize.x, floor(intXY.y / mosaicSize.y) * mosaicSize.y);
23 //换算回纹理坐标
24 vec2 UVMosaic = vec2(XYMosaic.x / TexSize.x, XYMosaic.y / TexSize.y);
25
26 yuv.x = texture2D(dataY,UVMosaic).r-0.0625;
27 yuv.y = texture2D(dataU,UVMosaic).r-0.5;
28 yuv.z = texture2D(dataV,UVMosaic).r-0.5;
29 }else
30 {
31 yuv.x = texture2D(dataY,TexCoord).r-0.0625;
32 yuv.y = texture2D(dataU,TexCoord).r-0.5;
33 yuv.z = texture2D(dataV,TexCoord).r-0.5;
34 }
35
36
37 rgb = mat3(1, 1, 1,
38 0, -0.18732, 1.8556,
39 1.57481, -0.46813, 0) * yuv;
40
41 FragColor = vec4(rgb.x, rgb.y,rgb.z,1);
42 };
有了局部马赛克，局部模糊如何实现呢？我们先做一个周围平均：
中间那个像覆盖上一层纱一样的东西的片元着色器：
1 #version 330 core
2 layout(location = 0) out vec4 FragColor;
3 in vec2 TexCoord;
4 uniform sampler2D dataY;
5 uniform sampler2D dataU;
6 uniform sampler2D dataV;
7 vec3 yuv;
8 vec3 rgb;
9
10
11 //片元着色器主要功能为通过重复执行(每片元一次),将3D物体中的图元光栅化后产生的每个片元的颜色等属性计算出来送入后继阶段
12 void main()
13 {
14
15 if( TexCoord.x > 0.3 && TexCoord.x <0.6 && TexCoord.y > 0.3 && TexCoord.y< 0.6)
16 {
17
18 vec2 tex_offset = 3.0 / textureSize(dataY, 0); //步长3 ，周围9个点
19 float result = texture(dataY, TexCoord).r ;
20 {
21
22 result += texture(dataY, TexCoord + vec2(tex_offset.x * 1, 0.0)).r ;
23 result += texture(dataY, TexCoord - vec2(tex_offset.x * 1, 0.0)).r;
24 result += texture(dataY, TexCoord + vec2(0.0, tex_offset.y * 1)).r ;
25 result += texture(dataY, TexCoord - vec2(0.0, tex_offset.y * 1)).r;
26 result += texture(dataY, TexCoord + vec2(tex_offset.x * 1, tex_offset.y * 1)).r ;
27 result += texture(dataY, TexCoord - vec2(tex_offset.x * 1, tex_offset.y * 1)).r;
28 result += texture(dataY, TexCoord + vec2(tex_offset.x * 1,-tex_offset.y * 1)).r ;
29 result += texture(dataY, TexCoord + vec2(-tex_offset.x * 1, tex_offset.y * 1)).r;
30
31 result = result/9.0;
32
33 }
34
35
36 vec2 tex_offset1 = 3.0 / textureSize(dataU, 0);
37 float result1 = (texture(dataU, TexCoord).r-0.5) ;
38
39 {
40 result1 += texture(dataU, TexCoord + vec2(tex_offset1.x * 1, 0.0)).r-0.5 ;
41 result1 += texture(dataU, TexCoord - vec2(tex_offset1.x * 1, 0.0)).r-0.5;
42 result1 += texture(dataU, TexCoord + vec2(0.0, tex_offset1.y * 1)).r-0.5 ;
43 result1 += texture(dataU, TexCoord - vec2(0.0, tex_offset1.y * 1)).r-0.5;
44 result1 += texture(dataU, TexCoord + vec2(tex_offset1.x * 1, tex_offset1.y * 1)).r-0.5 ;
45 result1 += texture(dataU, TexCoord - vec2(tex_offset1.x * 1, tex_offset1.y * 1)).r-0.5;
46 result1 += texture(dataU, TexCoord + vec2(tex_offset1.x * 1,-tex_offset1.y * 1)).r-0.5 ;
47 result1 += texture(dataU, TexCoord + vec2(-tex_offset1.x * 1, tex_offset1.y * 1)).r-0.5;
48
49 result1 = result1/9.0;
50
51 }
52
53 vec2 tex_offset2 = 1.0 / textureSize(dataV, 0);
54 float result2 = (texture(dataV, TexCoord).r-0.5) ;
55
56 {
57 result2 += texture(dataV, TexCoord + vec2(tex_offset1.x * 1, 0.0)).r -0.5;
58 result2 += texture(dataV, TexCoord - vec2(tex_offset1.x * 1, 0.0)).r-0.5;
59 result2 += texture(dataV, TexCoord + vec2(0.0, tex_offset1.y * 1)).r -0.5;
60 result2 += texture(dataV, TexCoord - vec2(0.0, tex_offset1.y * 1)).r-0.5;
61 result2 += texture(dataV, TexCoord + vec2(tex_offset1.x * 1, tex_offset1.y * 1)).r-0.5 ;
62 result2 += texture(dataV, TexCoord - vec2(tex_offset1.x * 1, tex_offset1.y * 1)).r-0.5;
63 result2 += texture(dataV, TexCoord + vec2(tex_offset1.x * 1,-tex_offset1.y * 1)).r-0.5 ;
64 result2 += texture(dataV, TexCoord + vec2(-tex_offset1.x * 1, tex_offset1.y * 1)).r-0.5;
65
66 result2 = result2/9.0;
67
68 }
69
70 yuv.x =result;
71 yuv.y = result1;
72 yuv.z = result2;
73
74
75 }else
76 {
77 yuv.x = texture2D(dataY,TexCoord).r-0.0625;
78 yuv.y = texture2D(dataU,TexCoord).r-0.5;
79 yuv.z = texture2D(dataV,TexCoord).r-0.5;
80
81 }
82
83
84 rgb = mat3(1, 1, 1,
85 0, -0.18732, 1.8556,
86 1.57481, -0.46813, 0) * yuv;
87
88 FragColor = vec4(rgb.x, rgb.y,rgb.z,1);
89 };
完整代码见马赛克1：OpenGL马赛克（八） - 邗影 - 博客园 (cnblogs.com)
标签：offset1,OpenGL,0.5,texture,tex,vec2,马赛克,TexCoord 来源： https://www.cnblogs.com/8335IT/p/16380494.html