//PASSES=3
precision highp float;

varying vec2 UV;
varying vec2 lastUV;
uniform vec2 mouse;
uniform float time;
uniform int pass;
uniform sampler2D pass0;
uniform sampler2D pass1;
uniform sampler2D lastPass;
uniform float ratio;

#define PI 3.14159265359
#define PI2 6.28318

void main(void){
    float x = UV.x * ratio;
    float y = UV.y;

    vec2 pos = vec2(x, y) - vec2(0.5);

    vec4 col = vec4(0.0);

    if(pass == 1){
        // Original pass: a simple circle
        vec2 center = vec2(0.0,0.0);


        vec2 m;

        m.x = 0.2 * cos(time * PI2);
        m.y = 0.2 * sin(-time * PI2);

        float md = distance(pos, m);
        float f = 0.001 + 0.04 * cos(10.0 * time * PI2);
        col = vec4(0.0, 0.01, 0.03, 0.0);

        if(md < f && md > 0.0){
            if(time < 0.5){
                col.rgba += vec4(0.7, 0.7, 0.1, 1.0);
            } else {
                col.rgba += vec4(0.5, 0.2, 0.5, 1.0);
            }
        }

        // Blend in last frame
        float d = 0.01;
        float d1 = 0.001 * cos(pos.x * 600.0 + pos.y * 600.0) + d;
        float d2 = 0.001 * cos(pos.x * 600.0 + pos.y * 600.0) + d;
        float d3 = 0.001 * cos(pos.x * 600.0 + pos.y * 600.0) + d;
        float d4 = 0.001 * cos(pos.x * 600.0 + pos.y * 600.0) + d;


        col += 0.23 * texture2D(pass1, lastUV + vec2(d1, 0.0)) * vec4(1.0, 0.4, 0.0, 0.0);
        col += 0.23 * texture2D(pass1, lastUV + vec2(-d2, 0.0));
        col += 0.23 * texture2D(pass1, lastUV + vec2(0.0, d3));
        col += 0.23 * texture2D(pass1, lastUV + vec2(0.0, -d4));

        col.rgb *= 0.99;

    } else if (pass == 2){
        col = texture2D(pass0, lastUV);
    } else if (pass == 3){
        col = texture2D(lastPass, lastUV);
    }

    col.a = 1.0;

    gl_FragColor = col;
}