RainbowDisco.frag

#ifdef GL_ES
precision mediump float;
#endif
//#define ABC
#define PI 3.14159

const float PI_by_three = 1.04720;
const float two_PI_by_three = 2.09440;

uniform vec2 u_resolution;
uniform vec2 u_mouse;
uniform float u_time;

vec2 res = u_resolution;

float diatance(vec2 p1, vec2 p2){
    return (
        sqrt(
            pow((p2.y - p1.y),2.0) + pow((p2.x - p1.x),2.0)
    ));
}

void main() {
    float time = u_time * 5.0 + (u_mouse.x/25.);
    float R,G,B,A, size, tmp, distanceFromCenter = res.x/3.0;
    vec2 center = vec2(res.x/2.0,res.y/2.0),//center
            p1,p2,p3;
    vec3 color;

    p1 = p2 = p3 = center;
    p1.y += distanceFromCenter;
    p2.x -= distanceFromCenter * sin(PI_by_three);
    p2.y -= distanceFromCenter * cos(PI_by_three);
    p3.x += distanceFromCenter * sin(PI_by_three);
    p3.y -= distanceFromCenter * cos(PI_by_three);

    size = distance(p1,p2)*((u_mouse.x/res.x) + 0.5);
    //size1 *= 0.2 + abs(sin(u_time));
    p1.x = center.x + (size * cos(time)) / 2.0;
    p1.y = center.y + (size * sin(time)) / 2.0;

    p2.x = center.x + (size * cos(time + two_PI_by_three)) / 2.0;
    p2.y = center.y + (size * sin(time + two_PI_by_three)) / 2.0;

    p3.x = center.x + (size * cos(time + 2.0*two_PI_by_three)) / 2.0;
    p3.y = center.y + (size * sin(time + 2.0*two_PI_by_three)) / 2.0;
    float dist;

    dist = distance(p1,gl_FragCoord.xy);
    if(dist <= size*2.0){
        tmp = (dist)/(size*2.0);
        B = 1.0-tmp;
    }
    else
        B = 0.0;

    dist = distance(p2,gl_FragCoord.xy);
    if(dist <= size*2.0){
        tmp = (dist)/(size*2.0);
        R = 1.0-tmp;
    }
    else
        R = 0.0;

    dist = distance(p3,gl_FragCoord.xy);
    if(dist <= size*2.){
        tmp = (dist)/(size*2.0);
        G = 1.0-tmp;
    }
    else
        G = 0.0;

    dist = distance(center,gl_FragCoord.xy);
    if(dist <= size*3.0){
        tmp = (dist)/(size*3.0);
        R += (1.0 - tmp)*0.3;
        G += (1.0 - tmp)*0.3;
        B += (1.0 - tmp)*0.3;
    }


    color = vec3(R,G,B);
    A = 1.0;
    gl_FragColor = vec4(color,A);
}