spookonomics/shaders/firefly/fragment.glsl

void main()
{
    float distanceToCenter = distance(gl_PointCoord, vec2(0.5));
    float strength = 0.05 / distanceToCenter - 0.1;
    gl_FragColor = vec4(1.0, 1.0, 1.0, clamp(strength, 0.0, 1.0));

    #include <tonemapping_fragment>
    #include <colorspace_fragment>
}