#ifdef GL_ES
precision highp float;
#endif

varying vec4 vColor;
varying vec3 vPosition;

uniform float f; // this is incremented every frame
uniform float t; // this is time in milliseconds since init

float plasma(vec2 pos) {
 return sin(pos.x) * cos(pos.y) * 0.5 + 0.5;
}

float radius(vec2 point, vec2 center) {
    return distance(point, center);
}

bool is_circle(vec2 point, vec2 center, float fradius) {
       float r = radius(point, center);
       if(r <= fradius) {
            return true;
       } else {
                return false;
       }
}

bool is_ring(vec2 point, vec2 center, vec2 radiuses) {
      return !is_circle(point, center, radiuses[0]) && is_circle(point, center, radiuses[0] + radiuses[1]);
}

vec2 getCirclePoint(vec2 center, float radius, float f) {
    return vec2(radius * sin(f) + center.x, radius * cos(f) + center.y);
}

int is_planet(float planetRadius, float orbitRadius, float speed) {
    vec2 p = vPosition.xy;

    if(is_circle(p, getCirclePoint(vec2(0.0), orbitRadius, t / 900.0 * speed), planetRadius)) {
        return 2;
    }

    if(is_ring(p, vec2(0.0), vec2(orbitRadius, 0.01))) {
        return 1;
    }

    return 0;
}

vec4 get_planet_color(float planetRadius, float orbitRadius, vec4 circleColor, float speed) {
    int planetComponent = is_planet(planetRadius, orbitRadius, speed);
    if(planetComponent == 2) {
        return circleColor;
    } else if(planetComponent == 1) {
        return vec4(0.1,0.1,0.1,1.0);
    }

    return vec4(0.0);
}


vec4 getColor() {
    vec2 p = vPosition.xy;

    if(is_circle(p, vec2(0.0), 0.05)) {
        return vec4(1.0, 1.0, 0.0, 1.0);
    }

    vec4 tmp;

    tmp = get_planet_color(0.03, 0.15, vec4(0.5, 0.5, 1.0, 1.0), 1.5);
    if(tmp.a != 0.0) {
        return tmp;
    }

    tmp = get_planet_color(0.05, 0.65, vec4(1.0, 0.0, 0.0, 1.0), 0.5);
    if(tmp.a != 0.0) {
        return tmp;
    }

    return vec4(vec3(0.0), 1.0);
}

void main(void) {
    gl_FragColor = getColor();
}