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uniform sampler2D tex;
uniform int operation;
uniform float width;
uniform float height;
uniform float opacity_factor;
#define CORRECTION 2.25
#define SIZE_ADDITION 3.0
vec4 get_texture_at_position(vec2 position) {
vec2 raw_position = position + vec2(CORRECTION, CORRECTION);
vec2 raw_uv = raw_position / vec2(max(1.0, width + SIZE_ADDITION), max(1.0, height + SIZE_ADDITION));
return texture2D(tex, raw_uv);
}
vec4 try_get_texture_at_position(vec2 position, inout int count) {
if (any(greaterThanEqual(position, vec2(width, height))) ||
any(lessThan(position, vec2(0.0, 0.0)))) {
return vec4(0.0);
} else {
count++;
return get_texture_at_position(position);
}
}
ivec2 get_corrected_position() {
vec2 raw_uv = cogl_tex_coord0_in.st;
vec2 raw_position = raw_uv * vec2(width + SIZE_ADDITION, height + SIZE_ADDITION);
return ivec2(raw_position - vec2(CORRECTION, CORRECTION));
}
void main() {
ivec2 corrected_position = get_corrected_position();
vec4 source_color = get_texture_at_position(vec2(corrected_position));
vec4 effect_color = source_color;
// 1-step derivative
if (operation == 0) {
vec4 color = vec4(0.0);
int c = 0;
color += try_get_texture_at_position(vec2(corrected_position) + vec2(0.0, 1.0), c);
color -= try_get_texture_at_position(vec2(corrected_position) + vec2(0.0, 0.0), c);
color += try_get_texture_at_position(vec2(corrected_position) + vec2(1.0, 0.0), c);
color -= try_get_texture_at_position(vec2(corrected_position) + vec2(0.0, 0.0), c);
if (c < 4) {
color = vec4(0.0);
}
effect_color = vec4(color.xyz, source_color.a);
} else
// 2-step derivative
if (operation == 1) {
vec4 color = vec4(0.0);
int c = 0;
color += try_get_texture_at_position(vec2(corrected_position) + vec2(0.0, 1.0), c);
color -= try_get_texture_at_position(vec2(corrected_position) + vec2(0.0, -1.0), c);
color += try_get_texture_at_position(vec2(corrected_position) + vec2(1.0, 0.0), c);
color -= try_get_texture_at_position(vec2(corrected_position) + vec2(-1.0, 0.0), c);
if (c < 4) {
color = vec4(0.0);
}
effect_color = vec4(color.xyz / 2.0, source_color.a);
} else
// laplacian
if (operation == 2) {
vec4 color = vec4(0.0);
color = -4.0 * get_texture_at_position(vec2(corrected_position));
color += get_texture_at_position(vec2(corrected_position) + vec2(0.0, 1.0));
color += get_texture_at_position(vec2(corrected_position) + vec2(0.0, -1.0));
color += get_texture_at_position(vec2(corrected_position) + vec2(1.0, 0.0));
color += get_texture_at_position(vec2(corrected_position) + vec2(-1.0, 0.0));
effect_color = vec4(color.xyz, source_color.a);
}
cogl_color_out = mix(source_color, effect_color, opacity_factor);
}
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