GLSL实现Image Filter 【转】

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mb5fdb131956bf3 2014-06-24 18:14:00

文章标签 4s 2d 数组权重着色器 文章分类 代码人生

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: