#ifdef GL_ES
precision mediump float;
#endif
uniform vec2 resolution;
uniform float time;
uniform sampler2D backbuffer;

float distanceFunction(vec3 p)
{ 
	float repeat = 0.8+.2*sin(time);
	//all
	vec3 allPos = vec3(sin(time),sin(time),-1.5*time);
	//tor
	vec3 torPos = p + vec3( 0.0+ 0.375* sin(time),-1.49,0.0)+allPos;
	//torPos = mod(vec3(p.x,p.y,p.z),1.0);
	//vec3 torPos = p;
	torPos = mod(torPos, repeat)-repeat/2.0;
  	vec2 t = vec2( 0.75,0.749);
	vec2 q = vec2(length(torPos.xz)-t.x,torPos.y);
  	float d2 = length(q)-t.y;
  	
	//sp
	
	vec3 spPos = p + vec3( 0.0,-0.77,0.0)+allPos;
	spPos = mod(spPos, repeat)-repeat/2.0;
	float d1 =length(spPos) - 0.8;
	return max(-d2,d1);
	
	//return d2;
}
 

vec3 getNormal(vec3 p)
{
  const float d = 0.0001;
  return
    normalize
    (
      vec3
      (
        distanceFunction(p+vec3(d,0.0,0.0))-distanceFunction(p+vec3(-d,0.0,0.0)),
        distanceFunction(p+vec3(0.0,d,0.0))-distanceFunction(p+vec3(0.0,-d,0.0)),
        distanceFunction(p+vec3(0.0,0.0,d))-distanceFunction(p+vec3(0.0,0.0,-d))
      )
    );
}
const vec3 alb =vec3(1.5,0.5,1.2);
//const vec3 amb =vec3(0.2,0.45,0.38);
const vec3 amb =vec3(0.,0.45,0.38);
const vec3 sp=vec3(2.5,1.0,1.25);
void main() {
  vec2 pos = (gl_FragCoord.xy*2.0 -resolution) / resolution.y;
 
  vec3 camPos = vec3(0.0, 1.4, 3.0);
  vec3 camDir = normalize( vec3(cos(time), -0.5*sin(time), -1.0) );
  vec3 camUp = vec3(0.0, 1.0, 0.0);
  vec3 camSide = cross(camDir, camUp);
vec3 lightDir = vec3(0.1,0.2,-0.5);
  float focus = 1.8;
 
  vec3 rayDir = normalize(camSide*pos.x + camUp*pos.y + camDir*focus);
 
  float t = 0.0, d;
  vec3 posOnRay = camPos;
 
  for(int i=0; i<16; ++i)
  {
    d = distanceFunction(posOnRay);
    if((d)<0.001) break; 
    t += d;
    posOnRay = camPos + t*rayDir;
  }
 
  vec4 blur = texture2D(backbuffer,gl_FragCoord.xy/resolution.xy);
  if(abs(d) < 0.1)
  {

    vec3 normal = getNormal(posOnRay);
	  float diff = dot(lightDir,normal);
	  vec3 halfVec = normalize(lightDir-camDir);
	  float spec = pow(max(dot(normal, halfVec), 0.0),20.0);
	  vec3 light = diff*vec3(1.0)+amb;
	  gl_FragColor = vec4(alb*light+spec*sp,1.0)+0.2*blur;
	  //gl_FragColor = blur;
	  
  }else
  {
    gl_FragColor = vec4(0.01,0.0,0.05,1.0);
  }
}