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#version 330 core
out vec4 frag_color;
in vec2 tex_coords;
uniform sampler2D texture1;
vec4
inversion()
{
vec4 result = vec4(1.0f-vec3(texture(texture1, tex_coords)), 1.0f);
return(result);
}
vec4
grayscale_average()
{
vec4 tex_color = texture(texture1, tex_coords);
float average = (tex_color.r+tex_color.g+tex_color.b)/3.0f;
vec4 result = vec4(average, average, average, 1.0f);
return(result);
}
vec4
grayscale_weights()
{
vec4 tex_color = texture(texture1, tex_coords);
float average = 0.2126*tex_color.r+0.7152*tex_color.g+0.0722f*tex_color.b;
vec4 result = vec4(average, average, average, 1.0f);
return(result);
}
const float offset = 1.0f/300.0f;
vec4
kernel_effect(float[9] kernel)
{
vec2 offsets[9] = vec2[](
vec2(-offset, offset), /* top-left */
vec2(0.0f, offset), /* top-center */
vec2(offset, offset), /* top-right */
vec2(-offset, 0.0f), /* center-left */
vec2(0.0f, 0.0f), /* center-center */
vec2(offset, 0.0f), /* center-right */
vec2(-offset, -offset), /* bottom-left */
vec2(0.0f, -offset), /* bottom-center */
vec2(offset, -offset) /* bottom-right */
);
vec3 sample_texture[9];
for (int offset_index = 0;
offset_index < 9;
++offset_index)
{
sample_texture[offset_index] =
vec3(texture(texture1, tex_coords+offsets[offset_index]));
}
vec3 color = vec3(0.0f);
for (int i = 0; i < 9; ++i)
color += sample_texture[i]*kernel[i];
return(vec4(color, 1.0f));
}
void
main(void)
{
float strange_kernel[9] = float[](
-1, -1, -1,
-1, 9, -1,
-1, -1, -1
);
float gaussian_blur_kernel[9] = float[](
1.0f/16.0f, 2.0f/16.0f, 1.0f/16.0f,
2.0f/16.0f, 4.0f/16.0f, 2.0f/16.0f,
1.0f/16.0f, 2.0f/16.0f, 1.0f/16.0f
);
float box_blur_kernel[9] = float[](
1.0f/9.0f, 1.0f/9.0f, 1.0f/9.0f,
1.0f/9.0f, 1.0f/9.0f, 1.0f/9.0f,
1.0f/9.0f, 1.0f/9.0f, 1.0f/9.0f
);
float edge_detection_kernel[9] = float[](
1.0f, 1.0f, 1.0f,
1.0f, -8.0f, 1.0f,
1.0f, 1.0f, 1.0f
);
float sharpening_kernel[9] = float[](
0.0f, -1.0f, 0.0f,
-1.0f, 5.0f, -1.0f,
0.0f, -1.0f, 0.0f
);
float sobel_kernel_vertical[9] = float[](
-1.0f, 0.0f, 1.0f,
-2.0f, 0.0f, 2.0f,
-1.0f, 0.0f, 0.0f
);
float sobel_kernel_horizontal[9] = float[](
-1.0f, -2.0f, -1.0f,
0.0f, 0.0f, 0.0f,
1.0f, 2.0f, 1.0f
);
float funny_kernel[9] = float[](
1.0f, 1.0f, 1.0f,
1.0f, -4.0f, 1.0f,
1.0f, 1.0f, 1.0f
);
/*
frag_color = kernel_effect(funny_kernel);
frag_color *= vec4(0.76f, 0.47f, 0.84f, 1.0f);
*/
frag_color = grayscale_weights();
}
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