blur.shadron

#include "plot.shadron"

image Input = file("julia.png") : map(clamp);

#define PXSIZE shadron_PixelSize

param int STEPS = 8;
param float SIGMA = 1;
param float blurRange = 8 : range(256);

glsl float blurWeight(float x) {
    return exp(-0.5*(x*x)/(SIGMA*SIGMA));
}

template <TEXTURE, DIRECTION>
glsl vec4 blur(vec2 coord) {
    vec4 total = vec4(0.0);
    float totalWeight = 0.0;
    for (int step = -STEPS; step <= STEPS; ++step) {
        vec2 texCoord = coord + DIRECTION*float(step)/float(STEPS)*blurRange*PXSIZE;
        float weight = blurWeight(float(step)/float(STEPS));
        total += weight*texture(TEXTURE, texCoord);
        totalWeight += weight;
    }
    return total / totalWeight;
}

image WeightPlot = glsl(plot<blurWeight, -1.0, +1.0, 0.0, 1.0, 0.125, 0.125>, 1024, 512) : resizable;

image Hblur = glsl(blur<Input, vec2(1.0, 0.0)>, sizeof(Input)) : map(clamp);
image GaussianBlur = glsl(blur<Hblur, vec2(0.0, 1.0)>, sizeof(Input));

export png_foreach(GaussianBlur, "output/?.png") : Input("input/?.png");