#version 450
// Relentless -  srtuss - 2013-09-09
// https://www.shadertoy.com/view/Iss3WS

// Collecting some design ideas for a new game project. Heavily inspired by movAX13h's io shader. Thanks to iq for his ray-plane-intersection code.

// srtuss, 2013

// collecting some design ideas for a new game project.
// no raymarching is used.

// if i could add a custom soundtrack, it'd use this one (essential for desired sensation)
// http://www.youtube.com/watch?v=1uFAu65tZpo


//#define GREEN_VERSION

// ** improved camera shaking
// ** cleaned up code
// ** added stuff to the gates



// *******************************************************************************************
// Please do NOT use this shader in your own productions/videos/games without my permission!
// If you'd still like to do so, please drop me a mail (stral@aon.at)
// *******************************************************************************************

layout(std140, set = 0, binding = 0) uniform UBO
{
   mat4 MVP;
   vec4 OutputSize;
   vec4 OriginalSize;
   vec4 SourceSize;
   uint FrameCount;
} global;

#pragma stage vertex
layout(location = 0) in vec4 Position;
layout(location = 1) in  vec2 TexCoord;
layout(location = 0) out vec2 vTexCoord;
const vec2 madd = vec2(0.5, 0.5);
void main()
{
   gl_Position = global.MVP * Position;
   vTexCoord = gl_Position.xy;
}

#pragma stage fragment
layout(location = 0) in vec2 vTexCoord;
layout(location = 0) out vec4 FragColor;
float iGlobalTime = float(global.FrameCount)*0.025;
vec2 iResolution = global.OutputSize.xy;

#define time iGlobalTime

vec2 rotate(vec2 p, float a)
{
	return vec2(p.x * cos(a) - p.y * sin(a), p.x * sin(a) + p.y * cos(a));
}
float box(vec2 p, vec2 b, float r)
{
	return length(max(abs(p) - b, 0.0)) - r;
}

// iq's ray-plane-intersection code
vec3 intersect(in vec3 o, in vec3 d, vec3 c, vec3 u, vec3 v)
{
	vec3 q = o - c;
	return vec3(
		dot(cross(u, v), q),
		dot(cross(q, u), d),
		dot(cross(v, q), d)) / dot(cross(v, u), d);
}

// some noise functions for fast developing
float rand11(float p)
{
    return fract(sin(p * 591.32) * 43758.5357);
}
float rand12(vec2 p)
{
    return fract(sin(dot(p.xy, vec2(12.9898, 78.233))) * 43758.5357);
}
vec2 rand21(float p)
{
	return fract(vec2(sin(p * 591.32), cos(p * 391.32)));
}
vec2 rand22(in vec2 p)
{
	return fract(vec2(sin(p.x * 591.32 + p.y * 154.077), cos(p.x * 391.32 + p.y * 49.077)));
}

float noise11(float p)
{
	float fl = floor(p);
	return mix(rand11(fl), rand11(fl + 1.0), fract(p));//smoothstep(0.0, 1.0, fract(p)));
}
float fbm11(float p)
{
	return noise11(p) * 0.5 + noise11(p * 2.0) * 0.25 + noise11(p * 5.0) * 0.125;
}
vec3 noise31(float p)
{
	return vec3(noise11(p), noise11(p + 18.952), noise11(p - 11.372)) * 2.0 - 1.0;
}

// something that looks a bit like godrays coming from the surface
float sky(vec3 p)
{
	float a = atan(p.x, p.z);
	float t = time * 0.1;
	float v = rand11(floor(a * 4.0 + t)) * 0.5 + rand11(floor(a * 8.0 - t)) * 0.25 + rand11(floor(a * 16.0 + t)) * 0.125;
	return v;
}

vec3 voronoi(in vec2 x)
{
	vec2 n = floor(x); // grid cell id
	vec2 f = fract(x); // grid internal position
	vec2 mg; // shortest distance...
	vec2 mr; // ..and second shortest distance
	float md = 8.0, md2 = 8.0;
	for(int j = -1; j <= 1; j ++)
	{
		for(int i = -1; i <= 1; i ++)
		{
			vec2 g = vec2(float(i), float(j)); // cell id
			vec2 o = rand22(n + g); // offset to edge point
			vec2 r = g + o - f;
			
			float d = max(abs(r.x), abs(r.y)); // distance to the edge
			
			if(d < md)
				{md2 = md; md = d; mr = r; mg = g;}
			else if(d < md2)
				{md2 = d;}
		}
	}
	return vec3(n + mg, md2 - md);
}

#define A2V(a) vec2(sin((a) * 6.28318531 / 100.0), cos((a) * 6.28318531 / 100.0))

float circles(vec2 p)
{
	float v, w, l, c;
	vec2 pp;
	l = length(p);
	
	
	pp = rotate(p, time * 3.0);
	c = max(dot(pp, normalize(vec2(-0.2, 0.5))), -dot(pp, normalize(vec2(0.2, 0.5))));
	c = min(c, max(dot(pp, normalize(vec2(0.5, -0.5))), -dot(pp, normalize(vec2(0.2, -0.5)))));
	c = min(c, max(dot(pp, normalize(vec2(0.3, 0.5))), -dot(pp, normalize(vec2(0.2, 0.5)))));
	
	// innerest stuff
	v = abs(l - 0.5) - 0.03;
	v = max(v, -c);
	v = min(v, abs(l - 0.54) - 0.02);
	v = min(v, abs(l - 0.64) - 0.05);
	
	pp = rotate(p, time * -1.333);
	c = max(dot(pp, A2V(-5.0)), -dot(pp, A2V(5.0)));
	c = min(c, max(dot(pp, A2V(25.0 - 5.0)), -dot(pp, A2V(25.0 + 5.0))));
	c = min(c, max(dot(pp, A2V(50.0 - 5.0)), -dot(pp, A2V(50.0 + 5.0))));
	c = min(c, max(dot(pp, A2V(75.0 - 5.0)), -dot(pp, A2V(75.0 + 5.0))));
	
	w = abs(l - 0.83) - 0.09;
	v = min(v, max(w, c));
	
	return v;
}

float shade1(float d)
{
	float v = 1.0 - smoothstep(0.0, mix(0.012, 0.2, 0.0), d);
	float g = exp(d * -20.0);
	return v + g * 0.5;
}

void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
	vec2 uv = fragCoord.xy / iResolution.xy;
	uv = uv * 2.0 - 1.0;
	uv.x *= iResolution.x / iResolution.y;
	
	
	// using an iq styled camera this time :)
	// ray origin
	vec3 ro = 0.7 * vec3(cos(0.2 * time), 0.0, sin(0.2 * time));
	ro.y = cos(0.6 * time) * 0.3 + 0.65;
	// camera look at
	vec3 ta = vec3(0.0, 0.2, 0.0);
	
	// camera shake intensity
	float shake = clamp(3.0 * (1.0 - length(ro.yz)), 0.3, 1.0);
	float st = mod(time, 10.0) * 143.0;
	
	// build camera matrix
	vec3 ww = normalize(ta - ro + noise31(st) * shake * 0.01);
	vec3 uu = normalize(cross(ww, normalize(vec3(0.0, 1.0, 0.2 * sin(time)))));
	vec3 vv = normalize(cross(uu, ww));
	// obtain ray direction
	vec3 rd = normalize(uv.x * uu + uv.y * vv + 1.0 * ww);
	
	// shaking and movement
	ro += noise31(-st) * shake * 0.015;
	ro.x += time * 2.0;
	
	float inten = 0.0;
	
	// background
	float sd = dot(rd, vec3(0.0, 1.0, 0.0));
	inten = pow(1.0 - abs(sd), 20.0) + pow(sky(rd), 5.0) * step(0.0, rd.y) * 0.2;
	
	vec3 its;
	float v, g;
	
	// voronoi floor layers
	for(int i = 0; i < 4; i ++)
	{
		float layer = float(i);
		its = intersect(ro, rd, vec3(0.0, -5.0 - layer * 5.0, 0.0), vec3(1.0, 0.0, 0.0), vec3(0.0, 0.0, 1.0));
		if(its.x > 0.0)
		{
			vec3 vo = voronoi((its.yz) * 0.05 + 8.0 * rand21(float(i)));
			v = exp(-100.0 * (vo.z - 0.02));
			
			float fx = 0.0;
			
			// add some special fx to lowest layer
			if(i == 3)
			{
				float crd = 0.0;//fract(time * 0.2) * 50.0 - 25.0;
				float fxi = cos(vo.x * 0.2 + time * 1.5);//abs(crd - vo.x);
				fx = clamp(smoothstep(0.9, 1.0, fxi), 0.0, 0.9) * 1.0 * rand12(vo.xy);
				fx *= exp(-3.0 * vo.z) * 2.0;
			}
			inten += v * 0.1 + fx;
		}
	}
	
	// draw the gates, 4 should be enough
	float gatex = floor(ro.x / 8.0 + 0.5) * 8.0 + 4.0;
	float go = -16.0;
	for(int i = 0; i < 4; i ++)
	{
		its = intersect(ro, rd, vec3(gatex + go, 0.0, 0.0), vec3(0.0, 1.0, 0.0), vec3(0.0, 0.0, 1.0));
		if(dot(its.yz, its.yz) < 2.0 && its.x > 0.0)
		{
			v = circles(its.yz);
			inten += shade1(v);
		}
		
		go += 8.0;
	}
	
	// draw the stream
	for(int j = 0; j < 20; j ++)
	{
		float id = float(j);
		
		vec3 bp = vec3(0.0, (rand11(id) * 2.0 - 1.0) * 0.25, 0.0);
		vec3 its = intersect(ro, rd, bp, vec3(1.0, 0.0, 0.0), vec3(0.0, 0.0, 1.0));
		
		if(its.x > 0.0)
		{
			vec2 pp = its.yz;
			float spd = (1.0 + rand11(id) * 3.0) * 2.5;
			pp.y += time * spd;
			pp += (rand21(id) * 2.0 - 1.0) * vec2(0.3, 1.0);
			float rep = rand11(id) + 1.5;
			pp.y = mod(pp.y, rep * 2.0) - rep;
			float d = box(pp, vec2(0.02, 0.3), 0.1);
			float foc = 0.0;
			float v = 1.0 - smoothstep(0.0, 0.03, abs(d) - 0.001);
			float g = min(exp(d * -20.0), 2.0);
			
			inten += (v + g * 0.7) * 0.5;
			
		}
	}
	
	inten *= 0.4 + (sin(time) * 0.5 + 0.5) * 0.6;
	
	// find a color for the computed intensity
#ifdef GREEN_VERSION
	vec3 col = pow(vec3(inten), vec3(2.0, 0.15, 9.0));
#else
	vec3 col = pow(vec3(inten), 1.5 * vec3(0.15, 2.0, 9.0));
#endif
	
	fragColor = vec4(col, 1.0);
}

void main(void)
{
  //just some shit to wrap shadertoy's stuff
  vec2 FragmentCoord = vTexCoord.xy*global.OutputSize.xy;
  FragmentCoord.y = -FragmentCoord.y;
  mainImage(FragColor,FragmentCoord);
}