http://blog.csdn.net/a3070173/archive/2008/11/27/3390477.aspx

1. 图像过滤无论是在作图工具还是特效的实现上都时有运用,这里发一些通常会使用到的图像
2. 过滤着色器供有需要的朋友参考.
3. 备注:这里列出的都是片元着色器,顶点着色器都是一样地简单变换顶点和传递纹理坐标.
4. 高斯过滤 - 常用于进行图像模糊
5. 横向过滤:
6. const int g_iWeightNumber = 17;
7. uniform sampler2D g_FilterTexture;  // 被过滤纹理
8. uniform float g_aryWeight[g_iWeightNumber]; // Blur权重数组
9. uniform vec2 g_aryVerticalOffset[g_iWeightNumber];  // 横向Blur偏移数组
10. void main()
11. {
12. vec4 vec4Sum = vec4(0.0);
13. for(int i = 0; i < g_iWeightNumber; ++i)
14. {
15. vec4Sum += texture2D(g_FilterTexture, gl_TexCoord[0].st + g_aryVerticalOffset[i])*g_aryWeight[i];
16. }
17. gl_FragColor = vec4Sum;
18. }
19. 纵向过滤:
20. const int g_iWeightNumber = 17;
21. uniform sampler2D g_FilterTexture;  // 被过滤纹理
22. uniform float g_aryWeight[g_iWeightNumber]; // Blur权重数组
23. uniform vec2 g_aryHorizontalOffset[g_iWeightNumber];    // 横向Blur偏移数组
24. void main()
25. {
26. vec4 vec4Sum = vec4(0.0);
27. for(int i = 0; i < g_iWeightNumber; ++i)
28. {
29. vec4Sum += texture2D(g_FilterTexture, gl_TexCoord[0].st + g_aryHorizontalOffset[i])*g_aryWeight[i];
30. }
31. gl_FragColor = vec4Sum;
32. }
33. Mean过滤 - 用于纹理抗锯齿
34. // Mean kernel
35. // 1 1 1
36. // 1 1 1
37. // 1 1 1
38. const int g_iWeightNumber = 9;
39. uniform sampler2D g_FilterTexture;  // 被过滤纹理
40. uniform float g_aryWeight[g_iWeightNumber]; // Blur权重数组
41. uniform vec2 g_aryOffset[g_iWeightNumber];  // 横向Blur偏移数组
42. void main()
43. {
44. vec4 vec4Sum = vec4(0.0);
45. if (gl_TexCoord[0].s < 0.495)
46. {
47. for(int i = 0; i < g_iWeightNumber; ++i)
48. {
49. vec4Sum += texture2D(g_FilterTexture, gl_TexCoord[0].st + g_aryOffset[i])*g_aryWeight[i];
50. }
51. }
52. else if (gl_TexCoord[0].s > 0.505)
53. {
54. vec4Sum = texture2D(g_FilterTexture, gl_TexCoord[0].st);
55. }
56. else
57. {
58. vec4Sum = vec4(1.0, 0.0, 0.0, 1.0);
59. }
60. gl_FragColor = vec4Sum;
61. }
62. Laplacian过滤 - 用于突显图像轮廓
63. // Edge detection kernel (Laplacian filter).
64. // 0  -1 0
65. // -1  4 -1
66. // 0  -1 0
67. const int g_iWeightNumber = 9;
68. uniform sampler2D g_FilterTexture;  // 被过滤纹理
69. uniform float g_aryWeight[g_iWeightNumber]; // Blur权重数组
70. uniform vec2 g_aryOffset[g_iWeightNumber];  // 横向Blur偏移数组
71. void main()
72. {
73. vec4 vec4Sum = vec4(0.0);
74. if (gl_TexCoord[0].s < 0.495)
75. {
76. for(int i = 0; i < g_iWeightNumber; ++i)
77. {
78. vec4Sum += texture2D(g_FilterTexture, gl_TexCoord[0].st + g_aryOffset[i])*g_aryWeight[i];
79. }
80. vec4 vec4BaseColor = texture2D(g_FilterTexture, gl_TexCoord[0].st);
81. vec4Sum += vec4BaseColor*0.1;
82. }
83. else if (gl_TexCoord[0].s > 0.505)
84. {
85. vec4Sum = texture2D(g_FilterTexture, gl_TexCoord[0].st);
86. }
87. else
88. {
89. vec4Sum = vec4(1.0, 0.0, 0.0, 1.0);
90. }
91. gl_FragColor = vec4Sum;
92. }
93. Emboss过滤 - used to simulate the relief of an image
94. // Emboss filter
95. // 2   0  0
96. // 0  -1  0
97. // 0   0  -1
98. const int g_iWeightNumber = 9;
99. uniform sampler2D g_FilterTexture;  // 被过滤纹理
100. uniform float g_aryWeight[g_iWeightNumber]; // Blur权重数组
101. uniform vec2 g_aryOffset[g_iWeightNumber];  // 横向Blur偏移数组
102. void main()
103. {
104. vec4 vec4Sum = vec4(0.0);
105. if (gl_TexCoord[0].s < 0.495)
106. {
107. for(int i = 0; i < g_iWeightNumber; ++i)
108. {
109. vec4Sum += texture2D(g_FilterTexture, gl_TexCoord[0].st + g_aryOffset[i])*g_aryWeight[i];
110. }
111. vec4Sum += 0.5;
112. }
113. else if (gl_TexCoord[0].s > 0.505)
114. {
115. vec4Sum = texture2D(g_FilterTexture, gl_TexCoord[0].st);
116. }
117. else
118. {
119. vec4Sum = vec4(1.0, 0.0, 0.0, 1.0);
120. }
121. gl_FragColor = vec4Sum;
122. }
123. Sharpness过滤 - 突显图像的细节
124. // Sharpness filter
125. // -1  -1  -1
126. // -1   9  -1
127. // -1  -1  -1
128. const int g_iWeightNumber = 9;
129. uniform sampler2D g_FilterTexture;  // 被过滤纹理
130. uniform float g_aryWeight[g_iWeightNumber]; // Blur权重数组
131. uniform vec2 g_aryOffset[g_iWeightNumber];  // 横向Blur偏移数组
132. void main()
133. {
134. vec4 vec4Sum = vec4(0.0);
135. if (gl_TexCoord[0].s < 0.495)
136. {
137. for(int i = 0; i < g_iWeightNumber; ++i)
138. {
139. vec4Sum += texture2D(g_FilterTexture, gl_TexCoord[0].st + g_aryOffset[i])*g_aryWeight[i];
140. }
141. }
142. else if (gl_TexCoord[0].s > 0.505)
143. {
144. vec4Sum = texture2D(g_FilterTexture, gl_TexCoord[0].st);
145. }
146. else
147. {
148. vec4Sum = vec4(1.0, 0.0, 0.0, 1.0);
149. }
150. gl_FragColor = vec4Sum;
151. }
152. Demo效果截图:
153. 
154. 
155. 
156. 
157. 
158. exe文件:http://www.fileupyours.com/view/219112/GLSL/Image%20Filter%20Demo.rar