precision mediump float;
float circle_transparency(vec2 uv, vec2 center, float radius) {
    float d = length(uv - center) - radius; // if d positive, then is outside circle
    return clamp(d,0.0,1.0); // if d between 0 and 1, blend for anti-aliasing.
}

void main(void) {
    vec2 uv = gl_FragCoord.xy;
    vec2 center = iResolution.xy * 0.5;
    float radius = 0.25 * iResolution.y;

    vec3 background = vec3(.2);
    vec3 foreground = vec3(1,0,0);
    float alpha = circle_transparency(uv, center, radius);

precision mediump float;
// Created by inigo quilez - iq/2013
// License Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

uniform vec3 iResolution; // viewport resolution (in pixels)
uniform float iGlobalTime; // shader playback time (in seconds)
uniform vec4 iMouse; // mouse pixel coords. xy: current pixel coords. zw = click pixel
uniform vec4 iDate; // (year, month, day, time in seconds)

float sdSegment( in vec2 p, in vec2 a, in vec2 b )
{
	vec2 pa = p-a, ba = b-a;
	float h = clamp( dot(pa,ba)/dot(ba,ba), 0.0, 1.0 );
	return length( pa - ba*h );

precision mediump float;
uniform vec2 resolution;
uniform float time;
float map(vec3 p){float d=length(p)-0.45; for(int i=0;i<4;i++){float fi=float(i); vec3 c=vec3(sin(time*.4+fi)*1.1,cos(time*.3+fi*1.7)*.55,fi*.55-1.0); d=min(d,length(p-c)-.22);} return d;}
vec3 normal(vec3 p){vec2 e=vec2(.01,0);return normalize(vec3(map(p+e.xyy)-map(p-e.xyy),map(p+e.yxy)-map(p-e.yxy),map(p+e.yyx)-map(p-e.yyx)));}
void main(){
 vec2 uv=(gl_FragCoord.xy*2.0-resolution.xy)/min(resolution.x,resolution.y); vec3 ro=vec3(0,0,3.0), rd=normalize(vec3(uv,-1.8)); float t=0.0, glow=0.0;
 for(int i=0;i<48;i++){vec3 p=ro+rd*t; float d=map(p); glow+=0.015/(0.02+abs(d)); if(d<.005||t>6.0)break; t+=d*.65;}
 vec3 col=vec3(0.01,0.015,0.04)+glow*vec3(0.12,0.35,0.9); if(t<6.0){vec3 n=normal(ro+rd*t); col+=max(dot(n,normalize(vec3(.4,.7,.5))),0.0)*vec3(.8,.9,1.0);} gl_FragColor=vec4(col,1.0);
}

precision mediump float;
uniform vec2 resolution;
uniform float time;
float circle(vec2 p, vec2 c, float r){ return length(p-c)-r; }
void main(){
 vec2 uv=(gl_FragCoord.xy*2.0-resolution.xy)/min(resolution.x,resolution.y);
 float d=10.0;
 for(int i=0;i<6;i++){
   float fi=float(i);
   vec2 c=0.48*vec2(sin(time*(0.4+fi*0.07)+fi*1.7), cos(time*(0.35+fi*0.05)+fi*2.1));
   d=min(d, circle(uv,c,0.22+0.04*sin(time+fi)));
 }
 float fill=smoothstep(0.035,-0.025,d);
 float glow=0.018/max(0.018,abs(d));

precision mediump float;

uniform float u_time;
uniform vec2 u_resolution;

// https://iquilezles.org/articles/distfunctions2d/
float sdfCircle(vec2 p, float r) {
  // note: sqrt(pow(p.x, 2.0) + pow(p.y, 2.0)) - r;
  return length(p) - r;
}

void main() {
  // note: set up uv coordinates
  vec2 uv = gl_FragCoord.xy / u_resolution;