gtk2/gsk/gl/resources/blur.glsl
Matthias Clasen 900a4e4d31 gsk: Move shader resources
Move the resources of each renderer to its subdirectory.
We've previously done that for the ngl renderer, but it
is better to be consistent and do it for all the renderers.
2021-04-03 08:24:58 -04:00

56 lines
1.6 KiB
GLSL

// VERTEX_SHADER:
uniform float u_blur_radius;
uniform vec2 u_blur_size;
uniform vec2 u_blur_dir;
_OUT_ vec2 pixel_step;
_OUT_ float pixels_per_side;
_OUT_ vec3 initial_gaussian;
const float PI = 3.14159265;
const float RADIUS_MULTIPLIER = 2.0;
void main() {
gl_Position = u_projection * u_modelview * vec4(aPosition, 0.0, 1.0);
vUv = vec2(aUv.x, aUv.y);
pixel_step = (vec2(1.0) / u_blur_size) * u_blur_dir;
pixels_per_side = floor(u_blur_radius * RADIUS_MULTIPLIER / 2.0);
float sigma = u_blur_radius / 2.0; // *shrug*
initial_gaussian.x = 1.0 / (sqrt(2.0 * PI) * sigma);
initial_gaussian.y = exp(-0.5 / (sigma * sigma));
initial_gaussian.z = initial_gaussian.y * initial_gaussian.y;
}
// FRAGMENT_SHADER:
_IN_ vec2 pixel_step;
_IN_ float pixels_per_side;
_IN_ vec3 initial_gaussian;
// blur_radius 0 is NOT supported and MUST be caught before.
// Partially from http://callumhay.blogspot.com/2010/09/gaussian-blur-shader-glsl.html
void main() {
vec3 incrementalGaussian = initial_gaussian;
float coefficientSum = 0.0;
vec4 sum = GskTexture(u_source, vUv) * incrementalGaussian.x;
coefficientSum += incrementalGaussian.x;
incrementalGaussian.xy *= incrementalGaussian.yz;
vec2 p = pixel_step;
for (int i = 1; i <= int(pixels_per_side); i++) {
sum += GskTexture(u_source, vUv - p) * incrementalGaussian.x;
sum += GskTexture(u_source, vUv + p) * incrementalGaussian.x;
coefficientSum += 2.0 * incrementalGaussian.x;
incrementalGaussian.xy *= incrementalGaussian.yz;
p += pixel_step;
}
gskSetOutputColor(sum / coefficientSum);
}