//#define VAPORWAVE
//f#define AA 2
//#define stereo

float jTime;

float amp(vec2 p){
    return smoothstep(1.,8.,abs(p.x));
    
}
float pow512(float a){
    a*=a;//^2
    a*=a;//^4
    a*=a;//^8
    a*=a;//^16
    a*=a;//^32
    a*=a;//^64
    a*=a;//^128
    a*=a;//^256
    return a*a;
}
float pow1d5(float a){
    return a*sqrt(a);
}
float hash21(vec2 co){
    return fract(sin(dot(co.xy,vec2(1.9898,7.233)))*45758.5433);
}
float hash(vec2 uv){
    float a = amp(uv);
    float w = a>0.?(1.-.4*pow512(.51+.49*sin((.02*(uv.y+.5*uv.x)-jTime)*2.))):0.;
    return a>0.?
        a*pow1d5(
        //texture(iChannel0,uv/iChannelResolution[0].xy).r
        hash21(uv)
        )*w
        :0.;
}

vec2 trinoise(vec2 uv){
    const float sq = sqrt(3./2.);
    uv.x *= sq;
    uv.y -= .5*uv.x;
    vec2 d = fract(uv);
    uv -= d;

    bool c = dot(d,vec2(1))>1.;

    vec2 dd = 1.-d;
    vec2 da = c?dd:d,db = c?d:dd;
    
    float nn = hash(uv+float(c));
    float n2 = hash(uv+vec2(1,0));
    float n3 = hash(uv+vec2(0,1));

    
    float nmid = mix(n2,n3,d.y);
    float ns = mix(nn,c?n2:n3,da.y);
    float dx = da.x/db.y;
    return vec2(mix(ns,nmid,dx),min(min((1.-dx)*db.y,da.x),da.y));
}


vec2 map(vec3 p){
    vec2 n = trinoise(p.xz);
    return vec2(p.y-2.*n.x,n.y);
}

vec3 grad(vec3 p){
    const vec2 e = vec2(.005,0);
    float a =map(p).x;
    return vec3(map(p+e.xyy).x-a
                ,map(p+e.yxy).x-a
                ,map(p+e.yyx).x-a)/e.x;

}

vec2 intersect(vec3 ro,vec3 rd){
    float d =0.,h=0.;
    for(int i = 0;i<500;i++){ //look nice with 50 iterations
        vec3 p = ro+d*rd;
        vec2 s = map(p);
        h = s.x;
        d+= h*.5;
        if(abs(h)<.003*d)
            return vec2(d,s.y);
        if(d>150.|| p.y>2.) break;
    }
    
    return vec2(-1);
}


void addsun(vec3 rd,vec3 ld,inout vec3 col){
    
	float sun = smoothstep(.21,.2,distance(rd,ld));
    
    if(sun>0.){
        float yd = (rd.y-ld.y);

        float a =sin(3.1*exp(-(yd)*14.)); 

        sun*=smoothstep(-.8,0.,a);

        col = mix(col,vec3(1.,.8,.4)*.75,sun);
    }
}


float starnoise(vec3 rd){
    float c = 0.;
    vec3 p = normalize(rd)*300.;
	for (float i=0.;i<4.;i++)
    {
        vec3 q = fract(p)-.5;
        vec3 id = floor(p);
        float c2 = smoothstep(.5,0.,length(q));
        c2 *= step(hash21(id.xz/id.y),.06-i*i*0.005);
        c += c2;
        p = p*.6+.5*p*mat3(3./5.,0,4./5.,0,1,0,-4./5.,0,3./5.);
    }
    c*=c;
    float g = dot(sin(rd*10.512),cos(rd.yzx*10.512));
    c*=smoothstep(-3.14,-.9,g)*.5+.5*smoothstep(-.3,1.,g);
    return c*c;
}

vec3 gsky(vec3 rd,vec3 ld,bool mask){
    float haze = exp2(-5.*(abs(rd.y)-.2*dot(rd,ld)));
    //float st = mask?pow512(texture(iChannel0,(rd.xy+vec2(300.1,100)*rd.z)*10.).r)*(1.-min(haze,1.)):0.;
    //float st = mask?pow512(hash21((rd.xy+vec2(300.1,100)*rd.z)*10.))*(1.-min(haze,1.)):0.;
    float st = mask?(starnoise(rd))*(1.-min(haze,1.)):0.;
    vec3 col=clamp(mix(vec3(.4,.1,.7),vec3(.7,.1,.4),haze)+st,0.,1.);
    if(mask)addsun(rd,ld,col);
    return col;
   
}


void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
    fragColor=vec4(0);
    #ifdef AA
    for(float x = 0.;x<1.;x+=1./float(AA)){
    for(float y = 0.;y<1.;y+=1./float(AA)){
    #else
        const float AA=1.,x=0.,y=0.;
    #endif
    vec2 uv = (2.*(fragCoord+vec2(x,y))-iResolution.xy)/iResolution.x;
    
	//float dt = fract(texture(iChannel0,float(AA)*(fragCoord+vec2(x,y))/iChannelResolution[0].xy).r+iTime);
    float dt = fract(hash21(float(AA)*(fragCoord+vec2(x,y)))+iTime);
    jTime = mod(iTime-dt*iTimeDelta*.25,4000.);
    vec3 ro = vec3(0.,1,(-2000.+jTime)*10.);
    
        #ifdef stereo
            ro+=vec3(.2*(float(uv.x>0.)-.5),0.,0.); //-= for x-view
            const float de = .9;
            uv.x=uv.x+.5*(uv.x>0.?-de:de);
            uv*=2.;
		#endif
        
    vec3 rd = normalize(vec3(uv,.75));//vec3(uv,sqrt(1.-dot(uv,uv)));
    
    vec2 i = intersect(ro,rd);
    float d = i.x;
    
    vec3 ld = normalize(vec3(0,.125+.05*sin(.1*jTime),1));

    vec3 fog = d>0.?exp2(-d*vec3(.14,.1,.28)):vec3(0.);
    vec3 sky = gsky(rd,ld,d<0.);
    
    vec3 p = ro+d*rd;
    vec3 n = normalize(grad(p));
    
    float diff = dot(n,ld)+.1*n.y;
    vec3 col = vec3(.1,.11,.18)*diff;
    
    vec3 rfd = reflect(rd,n); 
    vec3 rfcol = gsky(rfd,ld,true);
    
    col = mix(col,rfcol,.05+.95*pow(max(1.+dot(rd,n),0.),5.));
    #ifdef VAPORWAVE
    col = mix(col,vec3(.4,.5,1.),smoothstep(.05,.0,i.y));
    col = mix(sky,col,fog);
    col = sqrt(col);
    #else
    col = mix(col,vec3(.8,.1,.92),smoothstep(.05,.0,i.y));
    col = mix(sky,col,fog);
    //no gamma for that old cg look
    #endif
    if(d<0.)
        d=1e6;
    d=min(d,10.);
    fragColor += vec4(clamp(col,0.,1.),d<0.?0.:.1+exp2(-d));
     #ifdef AA
    }
    }
    fragColor/=float(AA*AA);
    #endif
    
}

/** SHADERDATA
{
	"title": "another synthwave sunset thing",
	"description": "I was thinking of a way to make pseudo tesselation noise and i made this to illustrate it, i might not be the first one to come up with this solution.",
	"model": "car"
}
*/