GLSL实现Image Filter

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

过滤着色器供有需要的朋友参考.

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.

高斯过滤 - 常用于进行图像模糊

横向过滤:

const int g_iWeightNumber = 17;

uniform sampler2D g_FilterTexture; // 被过滤纹理

uniform float g_aryWeight[g_iWeightNumber]; // Blur权重数组

uniform vec2 g_aryVerticalOffset[g_iWeightNumber]; // 横向Blur偏移数组

void main()

{

vec4 vec4Sum = vec4(0.0);

for(int i = 0; i < g_iWeightNumber; ++i)

{

vec4Sum += texture2D(g_FilterTexture, gl_TexCoord[0].st + g_aryVerticalOffset[i])*g_aryWeight[i];

}

gl_FragColor = vec4Sum;

}

纵向过滤:

const int g_iWeightNumber = 17;

uniform sampler2D g_FilterTexture; // 被过滤纹理

uniform float g_aryWeight[g_iWeightNumber]; // Blur权重数组

uniform vec2 g_aryHorizontalOffset[g_iWeightNumber]; // 横向Blur偏移数组

void main()

{

vec4 vec4Sum = vec4(0.0);

for(int i = 0; i < g_iWeightNumber; ++i)

{

vec4Sum += texture2D(g_FilterTexture, gl_TexCoord[0].st + g_aryHorizontalOffset[i])*g_aryWeight[i];

}

gl_FragColor = vec4Sum;

}

Mean过滤 - 用于纹理抗锯齿

// Mean kernel

// 1 1 1

// 1 1 1

// 1 1 1

const int g_iWeightNumber = 9;

uniform sampler2D g_FilterTexture; // 被过滤纹理

uniform float g_aryWeight[g_iWeightNumber]; // Blur权重数组

uniform vec2 g_aryOffset[g_iWeightNumber]; // 横向Blur偏移数组

void main()

{

vec4 vec4Sum = vec4(0.0);

if (gl_TexCoord[0].s < 0.495)

{

for(int i = 0; i < g_iWeightNumber; ++i)

{

vec4Sum += texture2D(g_FilterTexture, gl_TexCoord[0].st + g_aryOffset[i])*g_aryWeight[i];

}

}

else if (gl_TexCoord[0].s > 0.505)

{

vec4Sum = texture2D(g_FilterTexture, gl_TexCoord[0].st);

}

else

{

vec4Sum = vec4(1.0, 0.0, 0.0, 1.0);

}

gl_FragColor = vec4Sum;

}

Laplacian过滤 - 用于突显图像轮廓

// Edge detection kernel (Laplacian filter).

// 0 -1 0

// -1 4 -1

// 0 -1 0

const int g_iWeightNumber = 9;

uniform sampler2D g_FilterTexture; // 被过滤纹理

uniform float g_aryWeight[g_iWeightNumber]; // Blur权重数组

uniform vec2 g_aryOffset[g_iWeightNumber]; // 横向Blur偏移数组

void main()

{

vec4 vec4Sum = vec4(0.0);

if (gl_TexCoord[0].s < 0.495)

{

for(int i = 0; i < g_iWeightNumber; ++i)

{

vec4Sum += texture2D(g_FilterTexture, gl_TexCoord[0].st + g_aryOffset[i])*g_aryWeight[i];

}

vec4 vec4BaseColor = texture2D(g_FilterTexture, gl_TexCoord[0].st);

vec4Sum += vec4BaseColor*0.1;

}

else if (gl_TexCoord[0].s > 0.505)

{

vec4Sum = texture2D(g_FilterTexture, gl_TexCoord[0].st);

}

else

{

vec4Sum = vec4(1.0, 0.0, 0.0, 1.0);

}

gl_FragColor = vec4Sum;

}

Emboss过滤 - used to simulate the relief of an image

// Emboss filter

// 2 0 0

// 0 -1 0

// 0 0 -1

const int g_iWeightNumber = 9;

uniform sampler2D g_FilterTexture; // 被过滤纹理

uniform float g_aryWeight[g_iWeightNumber]; // Blur权重数组

uniform vec2 g_aryOffset[g_iWeightNumber]; // 横向Blur偏移数组

void main()

{

vec4 vec4Sum = vec4(0.0);

if (gl_TexCoord[0].s < 0.495)

{

for(int i = 0; i < g_iWeightNumber; ++i)

{

vec4Sum += texture2D(g_FilterTexture, gl_TexCoord[0].st + g_aryOffset[i])*g_aryWeight[i];

}

vec4Sum += 0.5;

}

else if (gl_TexCoord[0].s > 0.505)

{

vec4Sum = texture2D(g_FilterTexture, gl_TexCoord[0].st);

}

else

{

vec4Sum = vec4(1.0, 0.0, 0.0, 1.0);

}

gl_FragColor = vec4Sum;

}

Sharpness过滤 - 突显图像的细节

// Sharpness filter

// -1 -1 -1

// -1 9 -1

// -1 -1 -1

const int g_iWeightNumber = 9;

uniform sampler2D g_FilterTexture; // 被过滤纹理

uniform float g_aryWeight[g_iWeightNumber]; // Blur权重数组

uniform vec2 g_aryOffset[g_iWeightNumber]; // 横向Blur偏移数组

void main()

{

vec4 vec4Sum = vec4(0.0);

if (gl_TexCoord[0].s < 0.495)

{

for(int i = 0; i < g_iWeightNumber; ++i)

{

vec4Sum += texture2D(g_FilterTexture, gl_TexCoord[0].st + g_aryOffset[i])*g_aryWeight[i];

}

}

else if (gl_TexCoord[0].s > 0.505)

{

vec4Sum = texture2D(g_FilterTexture, gl_TexCoord[0].st);

}

else

{

vec4Sum = vec4(1.0, 0.0, 0.0, 1.0);

}

gl_FragColor = vec4Sum;

}

Demo效果截图:











exe文件:http://www.fileupyours.com/view/219112/GLSL/Image%20Filter%20Demo.rar