#version 110

#ifdef GL_ES
precision highp float;// ios
#endif

uniform float time;
uniform vec2 resolution;

#define speedAll 0.06
#define iterations 12
#define formuparam2 0.79

#define volsteps 7
#define stepsize 0.290

#define zoom 1.0
#define tile   0.850
#define speed2  0.2

#define brightness 0.0015
#define darkmatter 0.100
#define distfading 0.560
#define saturation 0.90

#define transverseSpeed zoom
#define cloud 0.17

float triangle(float x, float a) {
    float output2 = 2.0*abs(3.0*  ((x/a) - floor((x/a) + 0.5))) - 1.0;
    return output2;
}

float field(in vec3 p) {
    float strength = 7. + .03 * log(1.e-6 + fract(sin(time*speedAll) * 373.11));
    float accum = 0.;
    float prev = 0.;
    float tw = 0.;

    for (int i = 0; i < 6; ++i) {
        float mag = dot(p, p);
        p = abs(p) / mag + vec3(-.5, -.8 + 0.1*sin(-time*speedAll*0.1 + 2.0), -1.1+0.3*cos(time*speedAll*0.3));
        float w = exp(-float(i) / 7.);
        accum += w * exp(-strength * pow(abs(mag - prev), 2.3));
        tw += w;
        prev = mag;
    }
    return max(0., 5. * accum / tw - .7);
}



void main() {
    vec2 uv2 = 2. * gl_FragCoord.xy / vec2(512) - 1.;
    vec2 uvs = uv2 * vec2(512)  / 512.;

    float time2 = time*speedAll;
    float speed = -speed2;
    speed = .005 * cos(time2*0.02 + 3.1415926/4.0);
    //speed = 0.0;	
    float formuparam = formuparam2;

    //get coords and direction	
    vec2 uv = uvs;
    float a_xz = 0.9;
    float a_yz = -.6;
    float a_xy = 0.9 + time*speedAll*0.08;

    mat2 rot_xz = mat2(cos(a_xz), sin(a_xz), -sin(a_xz), cos(a_xz));
    mat2 rot_yz = mat2(cos(a_yz), sin(a_yz), -sin(a_yz), cos(a_yz));
    mat2 rot_xy = mat2(cos(a_xy), sin(a_xy), -sin(a_xy), cos(a_xy));

    float v2 =1.0;
    vec3 dir=vec3(uv*zoom, 1.);
    vec3 from=vec3(0.0, 0.0, 0.0);
    from.x += 1.0;
    from.y += 1.0;

    vec3 forward = vec3(0., 0., 1.);
    from.x += transverseSpeed*(1.0)*cos(0.01*time*speedAll) + 0.001*time*speedAll;
    from.y += transverseSpeed*(1.0)*sin(0.01*time*speedAll) +0.001*time*speedAll;
    from.z += 0.003*time*speedAll;

    dir.xy*=rot_xy;
    forward.xy *= rot_xy;
    dir.xz*=rot_xz;
    forward.xz *= rot_xz;
    dir.yz*= rot_yz;
    forward.yz *= rot_yz;

    from.xy*=-rot_xy;
    from.xz*=rot_xz;
    from.yz*= rot_yz;

    //zoom
    float zooom = (time2-3311.)*speed;
    from += forward* zooom;
    float sampleShift = mod(zooom, stepsize);

    float zoffset = -sampleShift;
    sampleShift /= stepsize;// make from 0 to 1

    //volumetric rendering
    float s=0.24;
    float s3 = s + stepsize/2.0;
    vec3 v=vec3(0.);
    float t3 = 0.0;

    vec3 backCol2 = vec3(0.);
    for (int r=0; r<volsteps; r++) {
        vec3 p2=from+(s+zoffset)*dir;// + vec3(0.,0.,zoffset);
        vec3 p3=from+(s3+zoffset)*dir;// + vec3(0.,0.,zoffset);

        p2 = abs(vec3(tile)-mod(p2, vec3(tile*2.)));// tiling fold
        p3 = abs(vec3(tile)-mod(p3, vec3(tile*2.)));// tiling fold		
        #ifdef cloud
        t3 = field(p3);
        #endif

        float pa, a=pa=0.;
        for (int i=0; i<iterations; i++) {
            //p2=abs(p2)/dot(p2, p2)-formuparam;// the magic formula
            p2=abs(p2)/max(dot(p2, p2), 0.002)-formuparam;// another interesting way to reduce noise
            float D = abs(length(p2)-pa);// absolute sum of average change
            a += i > 7 ? min(12., D) : D;
            pa=length(p2);
        }


        //float dm=max(0.,darkmatter-a*a*.001); //dark matter
        a*=a*a;// add contrast
        //if (r>3) fade*=1.-dm; // dark matter, don't render near
        // brightens stuff up a bit
        float s1 = s+zoffset;
        // need closed form expression for this, now that we shift samples
        float fade = pow(distfading, max(0., float(r)-sampleShift));
        //t3 += fade;		
        v+=fade;
        //backCol2 -= fade;

        // fade out samples as they approach the camera
        if (r == 0)
        fade *= (1. - (sampleShift));
        // fade in samples as they approach from the distance
        if (r == volsteps-1)
        fade *= sampleShift;
        v+=vec3(s1, s1*s1, s1*s1*s1*s1)*a*brightness*fade;// coloring based on distance

        backCol2 += mix(.4, 1., v2) * vec3(1.8 * t3 * t3 * t3, 1.4 * t3 * t3, t3) * fade;


        s+=stepsize;
        s3 += stepsize;
    }//фор

    v=mix(vec3(length(v)), v, saturation);//color adjust	

    vec4 forCol2 = vec4(v*.01, 1.);
    #ifdef cloud
    backCol2 *= cloud;
    #endif
    backCol2.b *= 1.8;
    backCol2.r *= 0.05;

    backCol2.b = 0.5*mix(backCol2.g, backCol2.b, 0.8);
    backCol2.g = 0.0;
    backCol2.bg = mix(backCol2.gb, backCol2.bg, 0.5*(cos(time*speedAll*0.01) + 1.0));
    gl_FragColor = forCol2 + vec4(backCol2, 1.0);
}