the_pattern.frag

#ifdef GL_ES
precision mediump float;
#endif

uniform float time;
uniform vec2 resolution;
#define PI 3.1415926535898
#define EPS 0.01
const float clipFar = 100.0;
const float scaler = 1.0;

mat2 rot2( float a ) { float c = cos(a); float s = sin(a); return mat2( c, s,-s, c); }
float bump(vec3 p) { float t = 0.2*time*PI; return cos(p.x*t)*sin(p.y*t)*sin(-p.z*t);}

float map(vec3 p) {
  float b = bump(p/scaler);
  return length(p + b) - 2.5;
}

void main( void ) {
  vec2 uv = (2.0*gl_FragCoord.xy/resolution.xy - 1.0) * vec2(resolution.x/resolution.y, 1.0);
  vec3 lookAt   = vec3(0,0, 0.0);
  vec3 camPos   = lookAt + vec3(0, 0, lookAt.z - 2.0);
  vec3 lightPos = lookAt + vec3(0, 0, lookAt.z - 2.0);
  vec3 forward = normalize(camPos);
  vec3 right = vec3(forward.z, 0., -forward.x );
  vec3 up = cross(forward, right);
  vec3 rd = normalize(forward + uv.x*right + uv.y*up);

  rd.xz *= rot2(time * PI / 19.);
  // rd.yz *= rot2(PI / 2.);
  rd.yz *= rot2(sin(time *PI*.22)*PI/12.);
  
  float t = 0.0;
//  for (int i = 0 ; i < 1; i++) {
    float k = map(camPos + rd * t);
    t += k;
    // t += k * 0.35;
//    if ((k < 0.0) || (t > clipFar)) {
//      break;
//    }
//  }
  vec3 final  = vec3(0);
  vec3 p = camPos + rd * t;
  vec3 normal = normalize(vec3(
    map(vec3(p.x+EPS,p.y,p.z)) - map(vec3(p.x-EPS,p.y,p.z)),
    map(vec3(p.x,p.y+EPS,p.z)) - map(vec3(p.x,p.y-EPS,p.z)),
    map(vec3(p.x,p.y,p.z+EPS)) - map(vec3(p.x,p.y,p.z-EPS))
  ));
  vec3 lightDirection = normalize(lightPos - p);
  vec3 eyeDirection = normalize(camPos - p);
  float shade = 0.05 + 0.95 * max( 0.0, dot(normal, lightDirection) );
  final += shade;
  final += pow(max( 0.0, dot(reflect(-lightDirection, normal), eyeDirection) ), 12.0);
  float speed = 2.3;
  final += vec3(1.0, 0, 0) * cos(length(p + bump(p))*PI + time * PI * speed);
  final += vec3(1.0, 1.0, 0) * cos(length(p - bump(p))*PI + time * PI * speed*.8);

  gl_FragColor = vec4(clamp(pow(final, vec3(1.0 / 2.4)), 0.0, 1.0) , 1.0);
}