76 lines
No EOL
2.4 KiB
GLSL
76 lines
No EOL
2.4 KiB
GLSL
uniform sampler2D tex;
|
|
uniform int divider;
|
|
uniform float width;
|
|
uniform float height;
|
|
uniform int downsampling_mode;
|
|
|
|
#define CORRECTION 2.25
|
|
#define SIZE_ADDITION 3
|
|
|
|
vec4 get_texture_at_position(vec2 position) {
|
|
vec2 raw_position = position + vec2(CORRECTION, CORRECTION);
|
|
vec2 raw_uv = raw_position / vec2(width + SIZE_ADDITION, height + SIZE_ADDITION);
|
|
|
|
return texture2D(tex, raw_uv);
|
|
}
|
|
|
|
vec2 get_corrected_position() {
|
|
vec2 raw_uv = cogl_tex_coord0_in.st;
|
|
vec2 raw_position = raw_uv * vec2(width + SIZE_ADDITION, height + SIZE_ADDITION);
|
|
return raw_position - vec2(CORRECTION, CORRECTION);
|
|
}
|
|
|
|
void main() {
|
|
ivec2 corrected_position = ivec2(get_corrected_position());
|
|
vec2 multiplied_position = corrected_position * divider;
|
|
|
|
if (any(greaterThan(multiplied_position, vec2(width, height)))) {
|
|
discard;
|
|
}
|
|
|
|
// mode 0: boxcar downsampling
|
|
if (downsampling_mode == 0) {
|
|
|
|
vec4 color = vec4(0.);
|
|
int count = 0;
|
|
for (int i = 0; i < divider; i++) {
|
|
for (int j = 0; j < divider; j++) {
|
|
vec2 lookup_position = multiplied_position + vec2(i, j);
|
|
if (all(greaterThanEqual(lookup_position, vec2(0, 0))) &&
|
|
all(lessThan(lookup_position, vec2(width, height)))) {
|
|
color += get_texture_at_position(lookup_position);
|
|
count += 1;
|
|
}
|
|
}
|
|
}
|
|
cogl_color_out = color / count;
|
|
|
|
} else
|
|
// mode 1: triangular downsampling
|
|
if (downsampling_mode == 1) {
|
|
|
|
vec4 color = vec4(0.);
|
|
int count = 0;
|
|
int force = 1;
|
|
for (int i = 0; i < divider; i++) {
|
|
for (int j = 0; j < divider; j++) {
|
|
vec2 lookup_position = multiplied_position + vec2(i, j);
|
|
if (all(greaterThanEqual(lookup_position, vec2(0, 0))) &&
|
|
all(lessThan(lookup_position, vec2(width, height)))) {
|
|
force = 1 + divider - int(abs(divider - i - j));
|
|
color += get_texture_at_position(lookup_position) * force;
|
|
count += force;
|
|
}
|
|
}
|
|
}
|
|
cogl_color_out = color / count;
|
|
|
|
} else
|
|
// mode 2: Dirac downsampling
|
|
if (downsampling_mode == 2) {
|
|
|
|
vec2 lookup_position = min(multiplied_position + vec2(divider, divider) / 2, vec2(width - 1, height - 1));
|
|
cogl_color_out = get_texture_at_position(lookup_position);
|
|
|
|
}
|
|
} |