#version 450

layout(location = 0) in vec2 fragCoord;
layout(location = 0) out vec4 fragColor;

uniform mat4 qt_Matrix;
uniform float qt_Opacity;
uniform vec3 iResolution; // viewport resolution (in pixels)
uniform float iTime;      // shader playback time (in seconds)

float gTime = 0.;
const float REPEAT = 5.0;

//来自 https://www.shadertoy.com/view/tlVGDt

// 回転行列
mat2 rot(float a) {
    float c = cos(a), s = sin(a);

    return mat2(c,s,-s,c);
}

float sdBox( vec3 p, vec3 b ) {
    vec3 q = abs(p) - b;

    return length(max(q,0.0)) + min(max(q.x,max(q.y,q.z)),0.0);
}

float box(vec3 pos, float scale) {
    pos *= scale;
    float base = sdBox(pos, vec3(.4,.4,.1)) /1.5;
    pos.xy *= 5.;
    pos.y -= 3.5;
    pos.xy *= rot(.75);
    float result = -base;

    return result;
}

float box_set(vec3 pos, float iTime) {
    vec3 pos_origin = pos;
    pos = pos_origin;
    pos .y += sin(gTime * 0.4) * 2.5;
    pos.xy *=   rot(.8);
    float box1 = box(pos,2. - abs(sin(gTime * 0.4)) * 1.5);
    pos = pos_origin;
    pos .y -=sin(gTime * 0.4) * 2.5;
    pos.xy *=   rot(.8);
    float box2 = box(pos,2. - abs(sin(gTime * 0.4)) * 1.5);
    pos = pos_origin;
    pos .x +=sin(gTime * 0.4) * 2.5;
    pos.xy *=   rot(.8);
    float box3 = box(pos,2. - abs(sin(gTime * 0.4)) * 1.5);
    pos = pos_origin;
    pos .x -=sin(gTime * 0.4) * 2.5;
    pos.xy *=   rot(.8);
    float box4 = box(pos,2. - abs(sin(gTime * 0.4)) * 1.5);
    pos = pos_origin;
    pos.xy *=   rot(.8);
    float box5 = box(pos,.5) * 6.;
    pos = pos_origin;
    float box6 = box(pos,.5) * 6.;
    float result = max(max(max(max(max(box1,box2),box3),box4),box5),box6);

    return result;
}

float map(vec3 pos, float iTime) {
    vec3 pos_origin = pos;
    float box_set1 = box_set(pos, iTime);

    return box_set1;
}

void mainImage(out vec4 fragColor, in vec2 fragCoord) {
    vec2 p = (fragCoord.xy * 2. - iResolution.xy) / min(iResolution.x, iResolution.y);
    vec3 ro = vec3(0., -0.2 ,iTime * 4.);
    vec3 ray = normalize(vec3(p, 1.5));
    ray.xy = ray.xy * rot(sin(iTime * .03) * 5.);
    ray.yz = ray.yz * rot(sin(iTime * .05) * .2);
    float t = 0.1;
    vec3 col = vec3(0.);
    float ac = 0.0;

    for (int i = 0; i < 99; i++){
        vec3 pos = ro + ray * t;
        pos = mod(pos-2., 4.) -2.;
        gTime = iTime -float(i) * 0.01;

        float d = map(pos, iTime);

        d = max(abs(d), 0.01);
        ac += exp(-d*23.);

        t += d* 0.55;
    }

    col = vec3(ac * 0.02);

    col +=vec3(0.,0.2 * abs(sin(iTime)),0.5 + sin(iTime) * 0.2);

    fragColor = vec4(col, 1.0 - t * (0.02 + 0.02 * sin (iTime))) * qt_Opacity;
}

void main() {
    mainImage(fragColor, fragCoord);
}