#version 410 core

uniform float fGlobalTime; // in seconds
uniform vec2 v2Resolution; // viewport resolution (in pixels)

uniform sampler1D texFFT; // towards 0.0 is bass / lower freq, towards 1.0 is higher / treble freq
uniform sampler1D texFFTSmoothed; // this one has longer falloff and less harsh transients
uniform sampler1D texFFTIntegrated; // this is continually increasing
uniform sampler2D texChecker;
uniform sampler2D texNoise;
uniform sampler2D texTex1;
uniform sampler2D texTex2;
uniform sampler2D texTex3;
uniform sampler2D texTex4;

layout(location = 0) out vec4 out_color; // out_color must be written in order to see anything

mat2 rot(float a)
{
float c = cos(a); float s = sin(a);
return mat2(c,-s,s,c);
}


float map(vec3 pos)
{
  float sph = length(pos) - 1.;
  float pla = pos.y + 1. + sin(pos.z - fGlobalTime)*.1;

  pos.x = abs(pos.x);
  pos.z += fGlobalTime * 2. + (sin(fGlobalTime * 3.14159 ) * .5 + .5) * .1;
  pos.z = mod(pos.z + 2., 4.) - 2.;
  pos.x -= 3.;

  pos.xy *= rot(-.65);
  

  float cy = length(pos.xz) - .25;

  return min(min(sph, pla),cy);
}


float rayCast(vec3 ro,vec3 rd)
{
  vec3 cp = ro;

  float s = 0.;

  for(;s < 1.; s += 1. / 64.)
  {
    float cd = map(cp);
    if(cd < .01)
      break;
    cp += cd * rd * .75;
  }
  return s;
}

void main(void)
{
  vec2 uv = vec2(gl_FragCoord.x / v2Resolution.x, gl_FragCoord.y / v2Resolution.y);
  uv -= 0.5;
  uv /= vec2(v2Resolution.y / v2Resolution.x, 1);

  vec3 ro = vec3(0.,2.,-10.);
  vec3 rd = vec3(uv,1.);
  rd.yz *= rot(.1);

  float beat = exp(-mod(fGlobalTime * 10., 10.));

  beat *= .05;
  float r = rayCast(ro, rd + vec3(1.) * beat);
  float g = rayCast(ro, rd + vec3(1.,-1.,1.) * beat);
  float b = rayCast(ro, rd + vec3(1.,1.,-1.) * beat);
  float f = 1. - rayCast(ro, rd);
  out_color =  vec4(r,g,b,1.);
  out_color = out_color * sin(fGlobalTime) * .5 + .5;
}